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  • richardmitnick 10:27 pm on June 16, 2021 Permalink | Reply
    Tags: "How a supermassive black hole originates", , , , Black Hole science, , , , ,   

    From UC Riverside (US) : “How a supermassive black hole originates” 

    UC Riverside bloc

    From UC Riverside (US)

    June 16, 2021
    Iqbal Pittalwala

    1
    Messier 87*. Credit:Event Horizon Telescope-EHT

    Supermassive black holes, or SMBHs, are black holes with masses that are several million to billion times the mass of our sun. The Milky Way hosts an SMBH with mass a few million times the solar mass. Surprisingly, astrophysical observations show that SMBHs already existed when the universe was very young. For example, a billion solar mass black holes are found when the universe was just 6% of its current age, 13.7 billion years. How do these SMBHs in the early universe originate?

    A team led by a theoretical physicist at the University of California, Riverside, has come up with an explanation: a massive seed black hole that the collapse of a dark matter halo could produce.

    Dark matter halo is the halo of invisible matter surrounding a galaxy or a cluster of galaxies.

    Although Dark Matter has never been detected in laboratories, physicists remain confident this mysterious matter that makes up 85% of the universe’s matter exists. Were the visible matter of a galaxy not embedded in a dark matter halo, this matter would fly apart.

    “Physicists are puzzled why SMBHs in the early universe, which are located in the central regions of dark matter halos, grow so massively in a short time,” said Hai-Bo Yu, an associate professor of physics and astronomy at UC Riverside, who led the study that appears in The Astrophysical Journal Letters. “It’s like a 5-year-old child that weighs, say, 200 pounds. Such a child would astonish us all because we know the typical weight of a newborn baby and how fast this baby can grow. Where it comes to black holes, physicists have general expectations about the mass of a seed black hole and its growth rate. The presence of SMBHs suggests these general expectations have been violated, requiring new knowledge. And that’s exciting.”

    A seed black hole is a black hole at its initial stage — akin to the baby stage in the life of a human.

    “We can think of two reasons,” Yu added. “The seed — or ‘baby’ — black hole is either much more massive or it grows much faster than we thought, or both. The question that then arises is what are the physical mechanisms for producing a massive enough seed black hole or achieving a fast enough growth rate?”

    “It takes time for black holes to grow massive by accreting surrounding matter,” said co-author Yi-Ming Zhong, a postdoctoral researcher at the Kavli Institute for Cosmological Physics at the University of Chicago. “Our paper shows that if dark matter has self-interactions then the gravothermal collapse of a halo can lead to a massive enough seed black hole. Its growth rate would be more consistent with general expectations.”

    In astrophysics, a popular mechanism used to explain SMBHs is the collapse of pristine gas in protogalaxies in the early universe.

    “This mechanism, however, cannot produce a massive enough seed black hole to accommodate newly observed SMBHs — unless the seed black hole experienced an extremely fast growth rate,” Yu said. “Our work provides an alternative explanation: a self-interacting dark matter halo experiences gravothermal instability and its central region collapses into a seed black hole.”

    The explanation Yu and his colleagues propose works in the following way:

    Dark matter particles first cluster together under the influence of gravity and form a dark matter halo. During the evolution of the halo, two competing forces — gravity and pressure — operate. While gravity pulls dark matter particles inward, pressure pushes them outward. If dark matter particles have no self-interactions, then, as gravity pulls them toward the central halo, they become hotter, that is, they move faster, the pressure increases effectively, and they bounce back. However, in the case of self-interacting dark matter, dark matter self-interactions can transport the heat from those “hotter” particles to nearby colder ones. This makes it difficult for the dark matter particles to bounce back.

    Yu explained that the central halo, which would collapse into a black hole, has angular momentum, meaning, it rotates. The self-interactions can induce viscosity, or “friction,” that dissipates the angular momentum. During the collapse process, the central halo, which has a fixed mass, shrinks in radius and slows down in rotation due to viscosity. As the evolution continues, the central halo eventually collapses into a singular state: a seed black hole. This seed can grow more massive by accreting surrounding baryonic — or visible — matter such as gas and stars.

    “The advantage of our scenario is that the mass of the seed black hole can be high since it is produced by the collapse of a dark matter halo,” Yu said. “Thus, it can grow into a supermassive black hole in a relatively short timescale.”

    The new work is novel in that the researchers identify the importance of baryons—ordinary atomic and molecular particles — for this idea to work.

    “First, we show the presence of baryons, such as gas and stars, can significantly speed up the onset of the gravothermal collapse of a halo and a seed black hole could be created early enough,” said Wei-Xiang Feng, Yu’s graduate student and a co-author on the paper. “Second, we show the self-interactions can induce viscosity that dissipates the angular momentum remnant of the central halo. Third, we develop a method to examine the condition for triggering general relativistic instability of the collapsed halo, which ensures a seed black hole could form if the condition is satisfied.”

    Over the past decade, Yu has explored novel predictions of dark matter self-interactions and their observational consequences. His work [Physical Review Letters] has shown that self-interacting dark matter can provide a good explanation for the observed motion of stars and gas in galaxies.

    “In many galaxies, stars and gas dominate their central regions,” he said. “Thus, it’s natural to ask how the presence of this baryonic matter affects the collapse process. We show it will speed up the onset of the collapse. This feature is exactly what we need to explain the origin of supermassive black holes in the early universe. The self-interactions also lead to viscosity that can dissipate angular momentum of the central halo and further help the collapse process.”

    ______________________________________________________________________________________________________________

    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com.


    Coma cluster via NASA/ESA Hubble.


    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.
    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.
    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL).


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970

    Dark Matter Research

    Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington. Axion Dark Matter Experiment

    _____________________________________________________________________________________

    The study was funded by the Department of Energy (US); National Aeronautics Space Agency (US); the Kavli Institute for Cosmological Physics (US); and the John Templeton Foundation.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    UC Riverside Campus

    The University of California, Riverside (US) is a public land-grant research university in Riverside, California. It is one of the 10 campuses of the University of California (US) system. The main campus sits on 1,900 acres (769 ha) in a suburban district of Riverside with a branch campus of 20 acres (8 ha) in Palm Desert. In 1907, the predecessor to UC Riverside was founded as the UC Citrus Experiment Station, Riverside which pioneered research in biological pest control and the use of growth regulators responsible for extending the citrus growing season in California from four to nine months. Some of the world’s most important research collections on citrus diversity and entomology, as well as science fiction and photography, are located at Riverside.

    UC Riverside’s undergraduate College of Letters and Science opened in 1954. The Regents of the University of California declared UC Riverside a general campus of the system in 1959, and graduate students were admitted in 1961. To accommodate an enrollment of 21,000 students by 2015, more than $730 million has been invested in new construction projects since 1999. Preliminary accreditation of the UC Riverside School of Medicine was granted in October 2012 and the first class of 50 students was enrolled in August 2013. It is the first new research-based public medical school in 40 years.

    UC Riverside is classified among “R1: Doctoral Universities – Very high research activity.” The 2019 U.S. News & World Report Best Colleges rankings places UC Riverside tied for 35th among top public universities and ranks 85th nationwide. Over 27 of UC Riverside’s academic programs, including the Graduate School of Education and the Bourns College of Engineering, are highly ranked nationally based on peer assessment, student selectivity, financial resources, and other factors. Washington Monthly ranked UC Riverside 2nd in the United States in terms of social mobility, research and community service, while U.S. News ranks UC Riverside as the fifth most ethnically diverse and, by the number of undergraduates receiving Pell Grants (42 percent), the 15th most economically diverse student body in the nation. Over 70% of all UC Riverside students graduate within six years without regard to economic disparity. UC Riverside’s extensive outreach and retention programs have contributed to its reputation as a “university of choice” for minority students. In 2005, UCR became the first public university campus in the nation to offer a gender-neutral housing option.UC Riverside’s sports teams are known as the Highlanders and play in the Big West Conference of the National Collegiate Athletic Association (NCAA) Division I. Their nickname was inspired by the high altitude of the campus, which lies on the foothills of Box Springs Mountain. The UC Riverside women’s basketball team won back-to-back Big West championships in 2006 and 2007. In 2007, the men’s baseball team won its first conference championship and advanced to the regionals for the second time since the university moved to Division I in 2001.

    History

    At the turn of the 20th century, Southern California was a major producer of citrus, the region’s primary agricultural export. The industry developed from the country’s first navel orange trees, planted in Riverside in 1873. Lobbied by the citrus industry, the UC Regents established the UC Citrus Experiment Station (CES) on February 14, 1907, on 23 acres (9 ha) of land on the east slope of Mount Rubidoux in Riverside. The station conducted experiments in fertilization, irrigation and crop improvement. In 1917, the station was moved to a larger site, 475 acres (192 ha) near Box Springs Mountain.

    The 1944 passage of the GI Bill during World War II set in motion a rise in college enrollments that necessitated an expansion of the state university system in California. A local group of citrus growers and civic leaders, including many UC Berkeley(US) alumni, lobbied aggressively for a UC-administered liberal arts college next to the CES. State Senator Nelson S. Dilworth authored Senate Bill 512 (1949) which former Assemblyman Philip L. Boyd and Assemblyman John Babbage (both of Riverside) were instrumental in shepherding through the State Legislature. Governor Earl Warren signed the bill in 1949, allocating $2 million for initial campus construction.

    Gordon S. Watkins, dean of the College of Letters and Science at University of California at Los Angeles(US), became the first provost of the new college at Riverside. Initially conceived of as a small college devoted to the liberal arts, he ordered the campus built for a maximum of 1,500 students and recruited many young junior faculty to fill teaching positions. He presided at its opening with 65 faculty and 127 students on February 14, 1954, remarking, “Never have so few been taught by so many.”

    UC Riverside’s enrollment exceeded 1,000 students by the time Clark Kerr became president of the University of California(US) system in 1958. Anticipating a “tidal wave” in enrollment growth required by the baby boom generation, Kerr developed the California Master Plan for Higher Education and the Regents designated Riverside a general university campus in 1959. UC Riverside’s first chancellor, Herman Theodore Spieth, oversaw the beginnings of the school’s transition to a full university and its expansion to a capacity of 5,000 students. UC Riverside’s second chancellor, Ivan Hinderaker led the campus through the era of the free speech movement and kept student protests peaceful in Riverside. According to a 1998 interview with Hinderaker, the city of Riverside received negative press coverage for smog after the mayor asked Governor Ronald Reagan to declare the South Coast Air Basin a disaster area in 1971; subsequent student enrollment declined by up to 25% through 1979. Hinderaker’s development of innovative programs in business administration and biomedical sciences created incentive for enough students to enroll at Riverside to keep the campus open.

    In the 1990s, the UC Riverside experienced a new surge of enrollment applications, now known as “Tidal Wave II”. The Regents targeted UC Riverside for an annual growth rate of 6.3%, the fastest in the UC system, and anticipated 19,900 students at UC Riverside by 2010. By 1995, African American, American Indian, and Latino student enrollments accounted for 30% of the UC Riverside student body, the highest proportion of any UC campus at the time. The 1997 implementation of Proposition 209—which banned the use of affirmative action by state agencies—reduced the ethnic diversity at the more selective UC campuses but further increased it at UC Riverside.

    With UC Riverside scheduled for dramatic population growth, efforts have been made to increase its popular and academic recognition. The students voted for a fee increase to move UC Riverside athletics into NCAA Division I standing in 1998. In the 1990s, proposals were made to establish a law school, a medical school, and a school of public policy at UC Riverside, with the UC Riverside School of Medicine and the School of Public Policy becoming reality in 2012. In June 2006, UC Riverside received its largest gift, 15.5 million from two local couples, in trust towards building its medical school. The Regents formally approved UC Riverside’s medical school proposal in 2006. Upon its completion in 2013, it was the first new medical school built in California in 40 years.

    Academics

    As a campus of the University of California(US) system, UC Riverside is governed by a Board of Regents and administered by a president. The current president is Michael V. Drake, and the current chancellor of the university is Kim A. Wilcox. UC Riverside’s academic policies are set by its Academic Senate, a legislative body composed of all UC Riverside faculty members.

    UC Riverside is organized into three academic colleges, two professional schools, and two graduate schools. UC Riverside’s liberal arts college, the College of Humanities, Arts and Social Sciences, was founded in 1954, and began accepting graduate students in 1960. The College of Natural and Agricultural Sciences, founded in 1960, incorporated the CES as part of the first research-oriented institution at UC Riverside; it eventually also incorporated the natural science departments formerly associated with the liberal arts college to form its present structure in 1974. UC Riverside’s newest academic unit, the Bourns College of Engineering, was founded in 1989. Comprising the professional schools are the Graduate School of Education, founded in 1968, and the UCR School of Business, founded in 1970. These units collectively provide 81 majors and 52 minors, 48 master’s degree programs, and 42 Doctor of Philosophy (PhD) programs. UC Riverside is the only UC campus to offer undergraduate degrees in creative writing and public policy and one of three UCs (along with University of California-Berkeley (US) and University of California-Irvine (US)) to offer an undergraduate degree in business administration. Through its Division of Biomedical Sciences, founded in 1974, UC Riverside offers the Thomas Haider medical degree program in collaboration with University of California-Los Angeles(US). UC Riverside’s doctoral program in the emerging field of dance theory, founded in 1992, was the first program of its kind in the United States, and UC Riverside’s minor in lesbian, gay and bisexual studies, established in 1996, was the first undergraduate program of its kind in the UC system. A new BA program in bagpipes was inaugurated in 2007.

    Research and economic impact

    UC Riverside operated under a $727 million budget in fiscal year 2014–15. The state government provided $214 million, student fees accounted for $224 million and $100 million came from contracts and grants. Private support and other sources accounted for the remaining $189 million. Overall, monies spent at UC Riverside have an economic impact of nearly $1 billion in California. UC Riverside research expenditure in FY 2018 totaled $167.8 million. Total research expenditures at UC Riverside are significantly concentrated in agricultural science, accounting for 53% of total research expenditures spent by the university in 2002. Top research centers by expenditure, as measured in 2002, include the Agricultural Experiment Station; the Center for Environmental Research and Technology; the Center for Bibliographical Studies; the Air Pollution Research Center; and the Institute of Geophysics and Planetary Physics.

    Throughout UC Riverside’s history, researchers have developed more than 40 new citrus varieties and invented new techniques to help the $960 million-a-year California citrus industry fight pests and diseases. In 1927, entomologists at the CES introduced two wasps from Australia as natural enemies of a major citrus pest, the citrophilus mealybug, saving growers in Orange County $1 million in annual losses. This event was pivotal in establishing biological control as a practical means of reducing pest populations. In 1963, plant physiologist Charles Coggins proved that application of gibberellic acid allows fruit to remain on citrus trees for extended periods. The ultimate result of his work, which continued through the 1980s, was the extension of the citrus-growing season in California from four to nine months. In 1980, UC Riverside released the Oroblanco grapefruit, its first patented citrus variety. Since then, the citrus breeding program has released other varieties such as the Melogold grapefruit, the Gold Nugget mandarin (or tangerine), and others that have yet to be given trademark names.

    To assist entrepreneurs in developing new products, UC Riverside is a primary partner in the Riverside Regional Technology Park, which includes the City of Riverside and the County of Riverside. It also administers six reserves of the University of California Natural Reserve System. UC Riverside recently announced a partnership with China Agricultural University[中国农业大学](CN) to launch a new center in Beijing, which will study ways to respond to the country’s growing environmental issues. UC Riverside can also boast the birthplace of two name reactions in organic chemistry, the Castro-Stephens coupling and the Midland Alpine Borane Reduction.

     
  • richardmitnick 12:13 pm on June 10, 2021 Permalink | Reply
    Tags: "A study shows the unexpected effect of black holes beyond their own galaxies", , , , Black Hole science, , , Illustris-TNG collaboration   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : Women in STEM- Annalisa Pillepich “A study shows the unexpected effect of black holes beyond their own galaxies” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    09/06/2021

    1
    Artistic composition of a supermassive black hole regulating the evolution of its environment. Credit: Gabriel Pérez Díaz, SMM (IAC) and Dylan Nelson (Illustris-TNG).

    At the heart of almost every sufficiently massive galaxy there is a black hole whose gravitational field, although very intense, affects only a small region around the centre of the galaxy. Even though these objects are thousands of millions of times smaller than their host galaxies our current view is that the Universe can be understood only if the evolution of galaxies is regulated by the activity of these black holes, because without them the observed properties of the galaxies cannot be explained.

    Theoretical predictions suggest that as these black holes grow they generate sufficient energy to heat up and drive out the gas within galaxies to great distances. Observing and describing the mechanism by which this energy interacts with galaxies and modifies their evolution is therefore a basic question in present day Astrophysics.

    With this aim in mind, a study led by Ignacio Martín Navarro, a researcher at the Instituto de Astrofísica de Canarias (IAC), has gone a step further and has tried to see whether the matter and energy emitted from around these black holes can alter the evolution, not only of the host galaxy, but also of the satellite galaxies around it, at even greater distances. To do this, the team has used the Sloan Digital Sky Survey (US), which allowed them to analyse the properties of the galaxies in thousands of groups and clusters.

    The conclusions of this study, started during Ignacio’s stay at the MPG Institute for Astrophysics [MPG Institut für Astrophysik](DE), are published today in Nature magazine.

    “Surprisingly we found that the satellite galaxies formed more or fewer stars depending on their orientation with respect to the central galaxy”, explains Annalisa Pillepich, researcher at the MPG Institute for Astronomy [MPG Institut für Astronomie](DE) and co-author of the article. To try to explain this geometrical effect on the properties of the satellite galaxies the researchers used a cosmological simulation of the Universe called Illustris-TNG whose code contains a specific way of handling the interaction between central black holes and their host galaxies.

    “Just as with the observations, the Illustris-TNG simulation shows a clear modulation of the star formation rate in satellite galaxies depending on their position with respect to the central galaxy”, she adds.

    This result is doubly important because it gives observational support for the idea that central black holes play an important role in regulating the evolution of galaxies, which is a basic feature of our current understanding of the Universe. Nevertheless, this hypothesis is continually questioned, given the difficulty of measuring the possible effect of the black holes in real galaxies, rather than considering only theoretical implications.

    These results suggest, then, that there is a particular coupling between the black holes and their galaxies, by which they can expel matter to great distances from the galactic centres, and can even affect the evolution of other nearby galaxies. “So not only can we observe the effects of central black holes on the evolution of galaxies, but our analysis opens the way to understand the details of the interaction”, explains Ignacio Martín Navarro, who is the first author of the article.

    “This work has been possible due to collaboration between two communities: the observers and the theorists which, in the field of extragalactic Astrophysics, are finding that cosmological simulations are a useful tool to understand how the Universe behaves”, he concludes.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.



    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 12:14 pm on May 24, 2021 Permalink | Reply
    Tags: "Do supermassive black holes merge to form binary systems?", Black Hole science,   

    From Pennsylvania State University (US): “Do supermassive black holes merge to form binary systems?” 

    Penn State Bloc

    From Pennsylvania State University (US)

    May 24, 2021
    Sam Sholtis

    1
    Penn State Professor of Astronomy and Astrophysics Micheal Eracleous at Kitt Peak National Observatory in Tuscon, Arizona. Image: Micheal Eracleous.

    At the center of most galaxies are black holes so massive — up to several billion times the mass of our sun — that they have earned the descriptor “supermassive.” Compare this to your run-of-the-mill stellar-mass black hole, a measly 10 to 100 times our sun’s mass. Understanding these supermassive black holes will help astronomers understand the origin and evolution of galaxies. One open question is whether they can form binaries.

    Stellar-mass black holes form binary systems, two black holes orbiting each other, if they form from the collapse of a binary star system, or possibly when two black holes capture each other in their gravitational pull. They spiral in, eventually merging in an event so powerful that it sends a ripple through space and time known as a gravitational wave. A few years ago, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves from such an event for the first time.

    Caltech /MIT Advanced aLigo .

    Theoretically then, the merging of two galaxies could result in a binary black hole of the supermassive variety, but so far astronomers have not unequivocally detected one of these events. Penn State Professor of Astronomy and Astrophysics Michael Eracleous is in the forefront of the hunt.

    “About ten years ago, several papers were published claiming to have detected binary supermassive black holes,” he said. “I had done some work on binary supermassive black holes as a graduate student, so I felt compelled to embark on a project to gather a lot of data to be able to make a counterpoint to the claims of those papers. Once I got into it, I saw how connected it was to galaxy evolution.”

    “When I came to Penn State, I knew that the department was a perfect fit for the type of research that I do,” he said. “I’ve made some great connections with my colleagues here, and now I know that if I’m ever stuck, all it takes is a cup of coffee and a conversation to clear things up.”

    So how do you look for something you’ve never seen?

    “In much of astronomy, observation comes first — we see something and that informs our theory,” said Eracleous. “For binary supermassive black holes, theory is driving the observations. Until we find one, the questions are ‘Should they exist?’ and ‘Should we look for them?’ And the answer to both questions is definitely ‘Yes.’”

    A major difference between supermassive black holes and stellar-mass black holes is gas. When stellar-mass black holes form after a star explodes in a supernova, most of the gas is driven away. But supermassive black holes are thought to carry gases with them. These gases emit light signals that can be detected by large telescopes equipped with spectrographs here on Earth, such as the 11-meter Hobby-Eberly Telescope (HET).

    Eracleous explained that the gases are detected by the spectrograph as emission lines of a particular wavelength and they could hold the key to identifying a supermassive binary. As the black holes orbit one another, the emission lines from these gases shift due to the Doppler effect. The emission lines from one black hole are shifted to longer wavelengths, and those from the other are shifted to shorter wavelengths. So scientists expect two separate emission lines, one from each black hole.

    “If we could follow the emission lines over the course of an orbit, we would see them crossing back and forth as the signals from each black hole shifted one way and then the other,” said Eracleous.

    Of course, the actual search is not that straightforward. Practicalities like limited availability of time on the large telescopes necessary to make these observations mean astronomers can’t just watch and wait to see the telltale signs of a supermassive binary. But they don’t need to. Instead, they identify candidates from an initial survey and make regular check-ins to see if the spectra from these candidates have changed as would be expected based on theoretical models.

    “Using the Hobby-Eberly Telescope to make these observations makes our life easier because we don’t even need to go to the observatory to collect the data,” said Eracleous. “The HET is operated by resident astronomers who make the observations and send us the data.”

    The process is slow, but Eracleous explained that once they find one binary supermassive black hole, the search should accelerate.

    “The first confirmed binary supermassive black hole will be like the Rosetta Stone,” he said. “It will tell us which of our models were right and which were wrong. It will allow us to refine our next searches and we should be able to find more.”

    Astronomers are already developing the technology for those next searches. Eracleous is involved in the planning for the Laser Interferometer Space Antenna (LISA).

    LISA is to LIGO what a supermassive black hole is to a stellar-mass black hole. Where LIGO consists of two four-kilometer-long lasers at right angles to each other, LISA’s three spacecrafts will be connected by lasers that travel 2.5 million kilometers forming an equilateral triangle. LISA’s scale and the fact that it is space based means that it can detect low-wavelength gravitational waves away from noise sources here on Earth.

    “LISA will be tuned to find gravitational waves like those that would result from a supermassive black hole merger,” said Eracleous.

    For Eracleous, Penn State’s Department of Astronomy and Astrophysics has provided the supportive environment necessary for his search.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Penn State Campus

    The Pennsylvania State University (US) is a public state-related land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers’ High School of Pennsylvania, Penn State became the state’s only land-grant university in 1863. Today, Penn State is a major research university which conducts teaching, research, and public service. Its instructional mission includes undergraduate, graduate, professional and continuing education offered through resident instruction and online delivery. In addition to its land-grant designation, it also participates in the sea-grant, space-grant, and sun-grant research consortia; it is one of only four such universities (along with Cornell University(US), Oregon State University(US), and University of Hawaiʻi at Mānoa(US)). Its University Park campus, which is the largest and serves as the administrative hub, lies within the Borough of State College and College Township. It has two law schools: Penn State Law, on the school’s University Park campus, and Dickinson Law, in Carlisle. The College of Medicine is in Hershey. Penn State is one university that is geographically distributed throughout Pennsylvania. There are 19 commonwealth campuses and 5 special mission campuses located across the state. The University Park campus has been labeled one of the “Public Ivies,” a publicly funded university considered as providing a quality of education comparable to those of the Ivy League.

    Annual enrollment at the University Park campus totals more than 46,800 graduate and undergraduate students, making it one of the largest universities in the United States. It has the world’s largest dues-paying alumni association. The university offers more than 160 majors among all its campuses.

    Annually, the university hosts the Penn State IFC/Panhellenic Dance Marathon (THON), which is the world’s largest student-run philanthropy. This event is held at the Bryce Jordan Center on the University Park campus. The university’s athletics teams compete in Division I of the NCAA and are collectively known as the Penn State Nittany Lions, competing in the Big Ten Conference for most sports. Penn State students, alumni, faculty and coaches have received a total of 54 Olympic medals.

    Early years

    The school was sponsored by the Pennsylvania State Agricultural Society and founded as a degree-granting institution on February 22, 1855, by Pennsylvania’s state legislature as the Farmers’ High School of Pennsylvania. The use of “college” or “university” was avoided because of local prejudice against such institutions as being impractical in their courses of study. Centre County, Pennsylvania, became the home of the new school when James Irvin of Bellefonte, Pennsylvania, donated 200 acres (0.8 km2) of land – the first of 10,101 acres (41 km^2) the school would eventually acquire. In 1862, the school’s name was changed to the Agricultural College of Pennsylvania, and with the passage of the Morrill Land-Grant Acts, Pennsylvania selected the school in 1863 to be the state’s sole land-grant college. The school’s name changed to the Pennsylvania State College in 1874; enrollment fell to 64 undergraduates the following year as the school tried to balance purely agricultural studies with a more classic education.

    George W. Atherton became president of the school in 1882, and broadened the curriculum. Shortly after he introduced engineering studies, Penn State became one of the ten largest engineering schools in the nation. Atherton also expanded the liberal arts and agriculture programs, for which the school began receiving regular appropriations from the state in 1887. A major road in State College has been named in Atherton’s honor. Additionally, Penn State’s Atherton Hall, a well-furnished and centrally located residence hall, is named not after George Atherton himself, but after his wife, Frances Washburn Atherton. His grave is in front of Schwab Auditorium near Old Main, marked by an engraved marble block in front of his statue.

    Early 20th century

    In the years that followed, Penn State grew significantly, becoming the state’s largest grantor of baccalaureate degrees and reaching an enrollment of 5,000 in 1936. Around that time, a system of commonwealth campuses was started by President Ralph Dorn Hetzel to provide an alternative for Depression-era students who were economically unable to leave home to attend college.

    In 1953, President Milton S. Eisenhower, brother of then-U.S. President Dwight D. Eisenhower, sought and won permission to elevate the school to university status as The Pennsylvania State University. Under his successor Eric A. Walker (1956–1970), the university acquired hundreds of acres of surrounding land, and enrollment nearly tripled. In addition, in 1967, the Penn State Milton S. Hershey Medical Center, a college of medicine and hospital, was established in Hershey with a $50 million gift from the Hershey Trust Company.

    Modern era

    In the 1970s, the university became a state-related institution. As such, it now belongs to the Commonwealth System of Higher Education. In 1975, the lyrics in Penn State’s alma mater song were revised to be gender-neutral in honor of International Women’s Year; the revised lyrics were taken from the posthumously-published autobiography of the writer of the original lyrics, Fred Lewis Pattee, and Professor Patricia Farrell acted as a spokesperson for those who wanted the change.

    In 1989, the Pennsylvania College of Technology in Williamsport joined ranks with the university, and in 2000, so did the Dickinson School of Law. The university is now the largest in Pennsylvania. To offset the lack of funding due to the limited growth in state appropriations to Penn State, the university has concentrated its efforts on philanthropy.

     
  • richardmitnick 12:57 pm on May 20, 2021 Permalink | Reply
    Tags: "A Relic Black Hole in a Dwarf Galaxy", , , , , Black Hole science,   

    From AAS NOVA : “A Relic Black Hole in a Dwarf Galaxy” 

    AASNOVA

    From AAS NOVA

    19 May 2021
    Susanna Kohler

    1
    Henize 2-10 is an example of a dwarf galaxy that hosts an active galactic nucleus. A new technique may help us to discover similarly low-mass galaxies hosting the relics of supermassive black hole seeds. [X-ray (NASA/CXC/Virginia/A.Reines et al); Radio (NRAO/AUI/NSF); Optical (NASA/STScI)]

    Using a new technique, scientists have identified a supermassive black hole lurking in a low-mass, low-metallicity galaxy. Could this discovery be just the tip of the iceberg?

    Hunting for Seeds

    How did the first supermassive black holes — black holes of millions or billions of solar masses — form?

    Today, we know that giant black holes lie at the heart of most galaxies. Many of them have grown substantially since they first formed, via galaxy mergers and accretion of mass around them. But did they start out as large stars? Or collapse directly from molecular clouds? Or build up rapidly from the merger of smaller black holes?

    To identify the seeds of supermassive black holes and address these questions, we need to explore the least-disturbed supermassive black holes that we can find today. Small, low-metallicity galaxies — those that have had a peaceful cosmic history, devoid of the mergers that drive significant black-hole growth — are thus the perfect targets to search for the relics of supermassive black hole seeds.

    The catch? These are precisely the environments in which it’s difficult to spot black holes!

    A New Approach

    The easiest black holes to detect are those that are actively feeding, known as active galactic nuclei (AGNs). But the typical method for identifying an AGN — which relies on specific signatures in the source’s optical spectrum — is biased against low-metallicity and relatively merger-free galaxies, missing the precise population we want to find! Only a handful of AGNs have been identified in dwarf galaxies, and most of these lie in high-metallicity environments. So how do we find our seed relics?

    According to a team of scientists led by Jenna Cann (George Mason University (US)), it’s time for a different approach. Instead of relying on optical signatures, Cann and collaborators focus on finding coronal lines — near-infrared emission lines produced by ions that are excited by high-energy radiation. The presence of these lines can reveal a hidden AGN, even when a galaxy shows no sign of an AGN in optical emission.

    Discovery of a Relic

    In a recent study, Cann and collaborators demonstrate that their unique method works: they detected a coronal line in J1601+3113: a nearby, low-metallicity galaxy that’s only a tenth of the mass of the Large Magellanic Cloud! The authors’ detection is consistent with the presence of a supermassive black hole of roughly 100,000 solar masses, opening a window onto precisely the relic black hole seeds we’re hoping to find.

    Cann and collaborators’ discovery marks the first time that an AGN has been identified in a low-mass, low-metallicity galaxy with no optical signs of AGN activity, underscoring how the coronal-line technique can help us find AGNs that might otherwise go undetected.

    And with the James Webb Space Telescope scheduled to launch this year, we’ll (hopefully!) soon be collecting infrared spectra with unprecedented sensitivity. With any luck, we’re about to have access to a remarkable new population of lightweight AGNs hiding in small, low-metallicity galaxies — and with it, valuable insight into how these objects were born.

    Citation

    “Relics of Supermassive Black Hole Seeds: The Discovery of an Accreting Black Hole in an Optically Normal, Low Metallicity Dwarf Galaxy,” Jenna M. Cann et al 2021 ApJL 912 L2.

    https://iopscience.iop.org/article/10.3847/2041-8213/abf56d

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.


    Stem Education Coalition

    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

    The society was founded in 1899 through the efforts of George Ellery Hale. The constitution of the group was written by Hale, George Comstock, Edward Morley, Simon Newcomb and Edward Charles Pickering. These men, plus four others, were the first Executive Council of the society; Newcomb was the first president. The initial membership was 114. The AAS name of the society was not finally decided until 1915, previously it was the “Astronomical and Astrophysical Society of America”. One proposed name that preceded this interim name was “American Astrophysical Society”.

    The AAS today has over 7,000 members and six divisions – the Division for Planetary Sciences (1968); the Division on Dynamical Astronomy (1969); the High Energy Astrophysics Division (1969); the Solar Physics Division (1969); the Historical Astronomy Division (1980); and the Laboratory Astrophysics Division (2012). The membership includes physicists, mathematicians, geologists, engineers and others whose research interests lie within the broad spectrum of subjects now comprising contemporary astronomy.

    In 2019 three AAS members were selected into the tenth anniversary class of TED Fellows.

    The AAS established the AAS Fellows program in 2019 to “confer recognition upon AAS members for achievement and extraordinary service to the field of astronomy and the American Astronomical Society.” The inaugural class was designated by the AAS Board of Trustees and includes an initial group of 232 Legacy Fellows.

     
  • richardmitnick 12:06 am on March 9, 2021 Permalink | Reply
    Tags: "Establishing the Origin of Solar-Mass Black Holes and the Connection to Dark Matter", A definitive confirmation of the existence of black holes was celebrated with the 2020 physics Nobel Prize awarded to Andrea Ghez; Reinhard Genzel; and Roger Penrose., , , , Black Hole science, , , , Dark matter comprises the majority of matter in the Universe but its nature remains unknown., From Kavli Institute for the Physics and Mathematics of the Universe (IPMU) [カブリ数物連携宇宙研](JP) at U Tokyo {東京大学;Tōkyō daigaku](JP), Multiple gravitational wave detections of merging black holes have been identified by LIGO commemorated with the 2017 physics Nobel Prize to Kip Thorne; Barry Barish; and Rainer Weiss., What is the origin of black holes and how is that question connected with another mystery-the nature of Dark Matter?   

    From Kavli Institute for the Physics and Mathematics of the Universe (IPMU) [カブリ数物連携宇宙研](JP) at U Tokyo {東京大学;Tōkyō daigaku](JP) : “Establishing the Origin of Solar-Mass Black Holes and the Connection to Dark Matter” 

    KavliFoundation

    From Kavli Institute for the Physics and Mathematics of the Universe (IPMU) [カブリ数物連携宇宙研](JP) at U Tokyo {東京大学;Tōkyō daigaku](JP)

    Kavli IPMU

    March 5, 2021

    Research Contacts:
    Volodymyr Takhistov
    Project Researcher / Kavli IPMU Fellow
    Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
    volodymyr.takhistov@ipmu.jp

    George M. Fuller
    Distinguished Professor of Physics
    Director of Center for Astrophysics and Space Sciences
    Department of Physics, University of California, San Diego
    Email: gfuller@physics.ucsd.edu

    Alexander Kusenko
    Professor of Physics and Astronomy
    Department of Physics and Astronomy, University of California, Los Angeles,
    Visiting Senior Scientist
    Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
    kusenko@ucla.edu

    Media contact:
    John Amari
    Press officer
    Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
    press@ipmu.jp

    1
    Fig.1: [Left] A tiny primordial black hole being captured by a neutron star, subsequently devouring it and leaving a “transmuted” solar-mass black hole remnant behind. [Right] Expected mass distribution of “transmuted” solar-mass black holes following neutron stars formed as a result of a delayed or a rapid supernova. The LIGO GW190814 event with 2.6 solar-mass black hole candidate is also shown. Credit: Takhistov et. al.)

    What is the origin of black holes and how is that question connected with another mystery-the nature of Dark Matter*? Dark matter comprises the majority of matter in the Universe but its nature remains unknown.

    Multiple gravitational wave detections of merging black holes have been identified within the last few years by the Laser Interferometer Gravitational-Wave Observatory (LIGO) commemorated with the 2017 physics Nobel Prize to Kip Thorne; Barry Barish; and Rainer Weiss.

    3
    Left to right: Rainer Weiss, Barry Barish and Kip Thorne, who have been awarded the 2017 Nobel prize in physics. Credit: Molly Riley/AFP/Getty Images.

    Artist’s by now iconic conception of two merging black holes similar to those detected by LIGO. Credit: Caltech/MIT aLigo/Aurore Simonnet/Sonoma State.

    Caltech/MIT Advanced aLigo


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    ESA/eLISA the future of gravitational wave research

    A definitive confirmation of the existence of black holes was celebrated with the 2020 physics Nobel Prize awarded to Andrea Ghez; Reinhard Genzel; and Roger Penrose. Understanding the origin of black holes has thus emerged as a central issue in physics.

    2
    Roger Penrose, Reinhard Genzel and Andrea Ghez have won the the 2020 Nobel Prize for Physics. (Courtesy: IOP Publishing/Tushna Commissariat; CC-BY-SA H Garching; UCLA/Christopher Dibble)

    Surprisingly, LIGO has recently observed a 2.6 solar-mass black hole candidate (event GW190814, reported in Astrophysical Journal Letters). Assuming this is a black hole, and not an unusually massive neutron star, where does it come from?

    Solar-mass black holes are particularly intriguing, since they are not expected from conventional stellar evolution astrophysics. Such black holes might arise in the early Universe (primordial black holes) or be “transmuted” from existing neutron stars. Some black holes could have formed in the early universe long before the stars and galaxies formed. Such primordial black holes could make up some part or all of dark matter. If a neutron star captures a primordial black hole, the black hole consumes the neutron star from the inside, turning it into a solar-mass black hole. This process can produce a population of solar mass black holes, regardless of how small the primordial black holes are. Other forms of dark matter can accumulate inside a neutron star causing its eventual collapse into a solar-mass black hole.

    A new study, published in Physical Review Letters, advances a decisive test to investigate the origin of solar-mass black holes. This work was led by the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Fellow Volodymyr Takhistov and the international team included George M. Fuller, Distinguished Professor of Physics and Director of the Center for Astrophysics and Space Science at the University of California, San Diego(US), as well as Alexander Kusenko, Professor of Physics and Astronomy at the University of California, Los Angeles(US) and a Kavli IPMU Visiting Senior Scientist.

    As the study discusses (see Fig. 1), “transmuted” solar-mass black holes remaining from neutron stars being devoured by dark matter (either tiny primordial black holes or particle dark matter accumulation) should follow the mass-distribution of the original host neutron stars. Since the neutron star mass distribution is expected to peak around 1.5 solar masses, it is unlikely that heavier solar-mass black holes have originated from dark matter interacting with neutron stars. This suggests that such events as the candidate detected by LIGO, if they indeed constitute black holes, could be of primordial origin from the early Universe and thus drastically affect our understanding of astronomy. Future observations will use this test to investigate and identify the origin of black holes.

    Previously (see Physical Review Letters ), the same international team of researchers also demonstrated that disruption of neutron stars by small primordial black holes can lead to a rich variety of observational signatures and can help us understand such long-standing astronomical puzzles as the origin of heavy elements (e.g. gold and uranium) and the 511 keV gamma-ray excess observed from the center of our Galaxy.

    *Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com.


    Coma cluster via NASA/ESA Hubble.


    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.
    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.
    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL).


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Kavli Institute for the Physics and Mathematics of the Universe (IPMU) [カブリ数物連携宇宙研](JP) at U Tokyo {東京大学;Tōkyō daigaku](JP) is an international research institute with English as its official language. The goal of the institute is to discover the fundamental laws of nature and to understand the Universe from the synergistic perspectives of mathematics, astronomy, and theoretical and experimental physics. The Institute for the Physics and Mathematics of the Universe (IPMU) was established in October 2007 under the World Premier International Research Center Initiative (WPI) of the Ministry of Education, Sports, Science and Technology in Japan with the University of Tokyo as the host institution. IPMU was designated as the first research institute within the University of Tokyo Institutes for Advanced Study (UTIAS) in January 2011. It received an endowment from The Kavli Foundation and was renamed the “Kavli Institute for the Physics and Mathematics of the Universe” in April 2012. Kavli IPMU is located on the Kashiwa campus of the University of Tokyo, and more than half of its full-time scientific members come from outside Japan. http://www.ipmu.jp/

    The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

    The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

     
  • richardmitnick 9:51 am on February 23, 2021 Permalink | Reply
    Tags: "Really Small Black Holes Could Be Out There Devouring Neutron Stars From Within", , , , Black Hole science, , , Endoparasitic black hole, , , Tiny all-but-undetectable primordial black holes could be one of the mysterious sources of mass that contributes to Dark Matter.,   

    From University of Illinois at Urbana–Champaign via Science Alert(AU): “Really Small Black Holes Could Be Out There Devouring Neutron Stars From Within” 

    From University of Illinois at Urbana–Champaign

    via

    ScienceAlert

    Science Alert(AU)

    23 FEBRUARY 2021
    MICHELLE STARR

    1
    Credit: Victor de Schwanberg/Science Photo Library/Getty Images.

    Tiny, all-but-undetectable primordial black holes could be one of the mysterious sources of mass that contributes to Dark Matter. There are significant limits to their lifespan in open space, but in recent years, astrophysicists have asked: what if these black holes are in the core of neutron stars?

    Gradually, such black holes would accrete the neutron star, devouring it from within. These hypothetical systems are yet to be verified, but a new paper [Accretion onto a small black hole at the center of a neutron star], yet to be peer-reviewed, has calculated how long this devouring would take.

    This, in turn, could be used to analyse the current neutron star population to constrain the nature of the black holes considered as a dark matter candidate – whether they are primordial, dating back to the Big Bang, or black holes that formed inside neutron stars.

    Although we don’t know what dark matter is, it’s pretty fundamental to our understanding of the Universe: there simply isn’t enough matter we can directly detect – normal matter – to account for all the gravity. In fact, there’s so much gravity that scientists have calculated roughly 75 to 80 percent of all matter is dark.

    There are a number of candidate particles that could be dark matter. Primordial black holes that formed just after the Big Bang are not one of the leading candidates, because if they were above a certain mass we would have noticed them by now; but, below that mass, they would have evaporated via the emission of Hawking Radiation long before now.

    Black holes, however, are an attractive candidate for dark matter: they, too, are extremely difficult to detect if they’re just hanging out in space just doing nothing. So astronomers continue to look for them.

    One idea that has been explored recently is the endoparasitic black hole. There are two scenarios for this. One is that primordial black holes were captured by neutron stars, and sink down to the core. The other is that dark matter particles are captured inside a neutron star; if the conditions are favourable, these could then come together and collapse down into a black hole.

    These black holes are small, but they wouldn’t remain so. From their position, ensconced inside the neutron star, these little black holes would then parasitise their host.

    The team of physicists from Bowdoin College and the University of Illinois at Urbana-Champaign calculated the accretion rate – that is, the rate at which the black hole would devour the neutron star – for a range of black hole mass ratios, from three to nine orders of magnitude less massive than the neutron star host.

    Neutron stars have a theoretical upper mass limit of 2.3 times the mass of the Sun, so the black hole masses would extend down into the range of dwarf planets.

    For a non-rotating neutron star hosting a non-spinning black hole, the accretion would be spherical. At the team’s calculated accretion rates, black holes as small as 10-21 times the mass of the Sun would completely accrete a neutron star well within the lifetime of the Universe.

    This suggests that primordial black holes, from the beginning of the Universe, would have completely accreted their host neutron stars before now. These timescales are in direct conflict with the ages of old neutron star populations, the researchers said.

    “As an important application, our results corroborate arguments that use the current existence of neutron star populations to constrain either the contribution of primordial black holes to the dark matter content of the Universe, or that of dark matter particles that may form black holes at the center of neutron stars after they have been captured,” they wrote in their paper.

    So the result is another blow for primordial black holes; but it doesn’t rule endoparasitic black holes out entirely. If there are globs of dark matter particles out there floating through space and being slurped into neutron stars, they could be collapsing into black holes and converting neutron stars into black hole stuff even as you read this sentence.

    And that is freaking awesome.

    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com.


    Coma cluster via NASA/ESA Hubble.


    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.
    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.
    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL).


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The University of Illinois at Urbana-Champaign community of students, scholars, and alumni is changing the world.

    The University of Illinois at Urbana–Champaign (U of I, Illinois, or colloquially the University of Illinois or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the University of Illinois system and was founded in 1867.

    The University of Illinois at Urbana–Champaign is a member of the Association of American Universities and is classified among “R1: Doctoral Universities – Very high research activity”, and has been listed as a “Public Ivy” in The Public Ivies: America’s Flagship Public Universities (2001) by Howard and Matthew Greene. In fiscal year 2019, research expenditures at Illinois totaled $652 million. The campus library system possesses the second-largest university library in the United States by holdings after Harvard University. The university also hosts the National Center for Supercomputing Applications (NCSA) and is home to the fastest supercomputer on a university campus.

    The university contains 16 schools and colleges and offers more than 150 undergraduate and over 100 graduate programs of study. The university holds 651 buildings on 6,370 acres (2,578 ha). The University of Illinois at Urbana–Champaign also operates a Research Park home to innovation centers for over 90 start-up companies and multinational corporations, including Abbott, AbbVie, Caterpillar, Capital One, Dow, State Farm, and Yahoo, among others.

    As of August 2020, the alumni, faculty members, or researchers of the university include 30 Nobel laureates, 27 Pulitzer Prize winners, 2 Turing Award winners and 1 Fields medalist. Illinois athletic teams compete in Division I of the NCAA and are collectively known as the Fighting Illini. They are members of the Big Ten Conference and have won the second-most conference titles. Illinois Fighting Illini football won the Rose Bowl Game in 1947, 1952, 1964 and a total of five national championships. Illinois athletes have won 29 medals in Olympic events, ranking it among the top 40 American universities with Olympic medals.

    Illinois Industrial University

    The original University Hall, which stood until 1938, when it was replaced by Gregory Hall and the Illini Union. Pieces were used in the erection of Hallene Gateway dedicated in 1998.

    The University of Illinois, originally named “Illinois Industrial University”, was one of the 37 universities created under the first Morrill Land-Grant Act, which provided public land for the creation of agricultural and industrial colleges and universities across the United States. Among several cities, Urbana was selected in 1867 as the site for the new school.[19][20] From the beginning, President John Milton Gregory’s desire to establish an institution firmly grounded in the liberal arts tradition was at odds with many state residents and lawmakers who wanted the university to offer classes based solely around “industrial education”.[21] The university opened for classes on March 2, 1868, and had two faculty members and 77 students.

    The Library, which opened with the school in 1868, started with 1,039 volumes. Subsequently, President Edmund J. James, in a speech to the board of trustees in 1912, proposed to create a research library. It is now one of the world’s largest public academic collections. In 1870, the Mumford House was constructed as a model farmhouse for the school’s experimental farm. The Mumford House remains the oldest structure on campus. The original University Hall (1871) was the fourth building built; it stood where the Illini Union stands today.

    University of Illinois

    In 1885, the Illinois Industrial University officially changed its name to the “University of Illinois”, reflecting its agricultural, mechanical, and liberal arts curriculum.

    During his presidency, Edmund J. James (1904–1920) is credited for building the foundation for the large Chinese international student population on campus. James established ties with China through the Chinese Minister to the United States Wu Ting-Fang. In addition, during James’s presidency, class rivalries and Bob Zuppke’s winning football teams contributed to campus morale.

    Like many universities, the economic depression slowed construction and expansion on the campus. The university replaced the original university hall with Gregory Hall and the Illini Union. After World War II, the university experienced rapid growth. The enrollment doubled and the academic standing improved. This period was also marked by large growth in the Graduate College and increased federal support of scientific and technological research. During the 1950s and 1960s the university experienced the turmoil common on many American campuses. Among these were the water fights of the fifties and sixties.

    University of Illinois at Urbana–Champaign

    By 1967 the University of Illinois system consisted of a main campus in Champaign-Urbana and two Chicago campuses, Chicago Circle (UICC) and Medical Center (UIMC), and people began using “Urbana–Champaign” or the reverse to refer to the main campus specifically. The university name officially changed to the “University of Illinois at Urbana–Champaign” around 1982. While this was a reversal of the commonly used designation for the metropolitan area, “Champaign-Urbana,” most of the campus is located in Urbana. The name change established a separate identity for the main campus within the University of Illinois system, which today includes campuses in Springfield (UIS) and Chicago (UIC) (formed by the merger of UICC and UIMC).

    In 1998, the Hallene Gateway Plaza was dedicated. The Plaza features the original sandstone portal of University Hall, which was originally the fourth building on campus. In recent years, state support has declined from 4.5% of the state’s tax appropriations in 1980 to 2.28% in 2011, a nearly 50% decline. As a result, the university’s budget has shifted away from relying on state support with nearly 84% of the budget now coming from other sources.

    On March 12, 2015, the Board of Trustees approved the creation of a medical school, the first college created at Urbana–Champaign in 60 years. The Carle-Illinois College of Medicine began classes in 2018.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Illinois campus

    The University of Illinois at Urbana-Champaign community of students, scholars, and alumni is changing the world.

    With our land-grant heritage as a foundation, we pioneer innovative research that tackles global problems and expands the human experience. Our transformative learning experiences, in and out of the classroom, are designed to produce alumni who desire to make a significant, societal impact.

    The University of Illinois at Chicago (UIC) is a public research university in Chicago, Illinois. Its campus is in the Near West Side community area, adjacent to the Chicago Loop. The second campus established under the University of Illinois system, UIC is also the largest university in the Chicago area, having approximately 30,000 students enrolled in 15 colleges.

    UIC operates the largest medical school in the United States with research expenditures exceeding $412 million and consistently ranks in the top 50 U.S. institutions for research expenditures. In the 2019 U.S. News & World Report’s ranking of colleges and universities, UIC ranked as the 129th best in the “national universities” category. The 2015 Times Higher Education World University Rankings ranked UIC as the 18th best in the world among universities less than 50 years old.

    UIC competes in NCAA Division I Horizon League as the UIC Flames in sports. The Credit Union 1 Arena (formerly UIC Pavilion) is the Flames’ venue for home games.

     
  • richardmitnick 10:57 pm on February 18, 2021 Permalink | Reply
    Tags: "A Famous Black Hole Gets a Massive Update", , , , Black hole Cygnus X-1, Black Hole science, , ,   

    From The New York Times: “A Famous Black Hole Gets a Massive Update” 

    From The New York Times

    Feb. 18, 2021
    Dennis Overbye

    Cygnus X-1, one of the first identified black holes, is much weightier than expected, raising new questions about how such objects form.

    1
    An artist’s impression of the Cygnus X-1 system, a black hole with its orbiting companion star, HDE 226868, 7,200 light-years from Earth. Credit: ICRAR(AU).

    One of the biggest and first known black holes in the Milky Way galaxy is more massive than astronomers thought, a team of scientists announced on Thursday. The finding throws a wrench into long-held models of how massive stars evolve on the way to the ultimate doom.

    Cygnus X-1, an unseen, X-ray-emitting object, and a fat blue star called HDE 226868 circle each other every 5.6 days. Cygnus X-1 was one of the earliest celestial sources of X-rays ever discovered, in 1964, when astronomers began lofting cosmic Geiger counters into space, and one of the first to be considered as a possible black hole. The X-rays are produced by gas that is heated to millions of degrees as it swirls around the cosmic drain.

    With a mass originally estimated at 15 times that of the sun, Cygnus X-1 is one of the most massive and most luminous of the X-ray binary systems known in the Milky Way.

    New measurements have now raised that figure to 21 solar masses. The makeover does not change the overall perception of the cosmos; Cygnus X-1 is still a black hole, an almost science-fictional manifestation of Einsteinian weirdness in celestial reality. But the details of how Cygnus X-1 became a black hole are now in doubt.

    “A significant change in the mass of such a classic and historical astronomical source is a big deal (at least to astronomers),” Daniel Holz, a theoretical astrophysicist at the University of Chicago(US) who was not part of the study, wrote in an email.

    Also by email, James Miller-Jones of the ICRAR(AU) at Curtin University(AU) wrote: “We realized that a 21-solar-mass black hole was too massive to form in the Milky Way with the best existing estimates of the amount of mass lost by massive stars in stellar winds.”

    Dr. Miller-Jones and an international cast of colleagues reported the result in the journal Science and in a pair of companion papers in The Astrophysical Journal: Wind Mass-loss Rates of Stripped Stars Inferred from Cygnus X-1 . and Re-estimating the Spin Parameter of the Black Hole in Cygnus X-1 .

    Story of a black hole

    As one of the papers recounts, the story of Cygnus X-1 starts in the dim past with a pair of massive blue stars orbiting each other. The bigger of the two stars evolved faster, expanded and began spilling hydrogen gas onto its companion star. What remained of the primary star, which started out in its prime with a mass of 55 or 75 times that of the sun, shed more of its mass in fierce stellar winds as its core kept burning. Finally, having exhausted all of its thermonuclear fuel, the spent star collapsed into a black hole.

    Sometimes, depending on circumstance, this endgame collapse is marked by a stupendous supernova explosion.

    SN 1987A remnant, imaged by ALMA. The inner region is contrasted with the outer shell, lacy white and blue circles, where the blast wave from the supernova is colliding with the envelope of gas ejected from the star prior to its powerful detonation. Image credit: ALMA / ESO / NAOJ / NRAO / Alexandra Angelich, NRAO / AUI / NSF.

    In this case, however, Dr. Miller-Jones wrote in an email, “We think that the black hole formed via almost direct collapse into a black hole, rather than in a type II supernova explosion.” Such an explosion, he said, would have kicked the binary star pair out of an assemblage of similarly massive stars in which it formed and, apparently, still lives.

    Since then, the black hole has been feeding, pulling in gas from its puffed-up neighbor, which, with roughly 40 solar masses, has a lot to give, according to Dr. Miller-Jones.

    The new measurement of the mass of Cygnus X-1 was serendipitous. “We had not set out to remeasure the distance and black-hole mass,” Dr. Miller-Jones said. “But when we had analyzed our data, we realized its full potential.”

    In the spring of 2016, Dr. Miller-Jones and his group spent six days observing Cygnus X-1 with the National Radio Astronomy Observatory’s Very Long Baseline Array, a nationwide network of antennas operated out of Socorro, NM(US).

    NRAO/VLBA.

    They were trying to investigate the connection between X-ray-emitting gas flowing into the black hole and high-speed radio jets shooting out of it.

    But part of the process allowed them to triangulate the distance to Cygnus X-1, increasing it from about 6,000 light-years to a little over 7,000. Interestingly, Dr. Miller-James noted, this also brought the distance into better agreement with early results from the European Space Agency’s Gaia space telescope, whose measurements had been in mild tension with the previously accepted distance.

    ESA(EU)/GAIA satellite.

    When that change in distance was factored into the calculations of luminosity and mass, the black hole’s estimated mass grew by about 40 percent, to 21 solar masses.

    That was exciting, Dr. Miller-Jones said, but it was not until he talked to a theoretical colleague, Ilya Mandel of Monash University(AU), that he appreciated the full implications of what they had done.

    3
    Astronomers observed the Cygnus X-1 system from different angles, using the Earth’s orbit around the sun to measure the perceived movement of the system against the background stars. Credit: ICRAR(AU).

    The new estimate of mass put Cygnus X-1 above a kind of magic threshold. Astronomers know of a few dozen black hole X-ray binary systems in the Milky Way and nearby, all of which have imputed masses of less than 20 times that of the sun. That apparent limit suggested that it was hard for black holes to grow more massive, at least from the collapse of stars.

    But since 2016, the Laser Interferometer Gravitational-Wave Observatory, or LIGO, and Virgo antennas have been recording the collisions of black holes far out in space, many of them much larger than 20 solar masses.

    MIT /Caltech Advanced aLigo at Hanford, WA(US), Livingston, LA(US) and VIRGO Gravitational Wave interferometer, near Pisa(IT).

    “When the very first GW detection turned out to be a binary composed of two black holes, each of approximately 30 solar masses, it came as a profound shock to many in the community,” wrote Dr. Holz, who is part of a large team studying those results.

    Artist’s by now iconic conception of two merging black holes similar to those detected by LIGO. Credit: Caltech/MIT aLigo/Aurore Simonnet/Sonoma State.

    The contradiction was glaring. The LIGO results suggested that, in general, black holes were more massive than the X-ray results suggested. Much of what is assumed about stellar evolution comes from imagining the details of the cosmic winds that strip mass from dying stars as they sputter out and become black holes. The new results suggest that astronomers need to pare back their calculations of how stars lose their mass.

    “Having revised the mass of the black hole in Cygnus X-1 upward,” Dr. Miller-Jones said, “we realized that we would need to revise downward the mass-loss rate of massive stars in order to explain our measurements. This was the key insight that led us to write this paper, demonstrating the power of scientific collaboration, bringing a diverse range of skills together to attack an interesting problem.”

    Dr. Holz said he was not worried on behalf of the astronomers. The astrophysics of stellar evolution is very complicated, he noted, offering many knobs to turn in the calculations to help the results make sense. “As for making a black hole of this mass, my guess is that stellar modelers will be able to accommodate it without too much trouble,” he said. “They are a very creative bunch!”

    See the full article here .

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    Please help promote STEM in your local schools.

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  • richardmitnick 4:46 pm on February 13, 2021 Permalink | Reply
    Tags: "In Violation of Einstein Black Holes Might Have ‘Hair’", According to Einstein’s general theory of relativity black holes have only three observable properties: mass; spin; and charge. Additional properties- or “hair”- do not exist., All of this could allow us to probe ideas such as string theory and quantum gravity in a way that has never been possible before., , Black hole hair hair could be detected by gravitational wave observatories., Black hole hair if it exists is expected to be incredibly short-lived lasting just fractions of a second., Black Hole science, ESA Lisa, Instabilities would effectively give some regions of a black hole’s horizon a stronger gravitational pull than others., Instabilities would make otherwise identical black holes distinguishable., , , Some black holes might have instabilities on their event horizons., Yet scientists have begun to wonder if the “no-hair theorem” is strictly true.   

    From Quanta Magazine: “In Violation of Einstein Black Holes Might Have ‘Hair’” 

    From Quanta Magazine

    February 11, 2021
    Jonathan O’Callaghan

    1
    According to Einstein’s general theory of relativity, black holes have only three observable properties: mass, spin and charge. Additional properties, or “hair,” do not exist. Credit: Andriy_A/Shutterstock.

    Identical twins have nothing on black holes. Twins may grow from the same genetic blueprints, but they can differ in a thousand ways — from temperament to hairstyle. Black holes, according to Albert Einstein’s theory of general relativity, can have just three characteristics — mass, spin and charge. If those values are the same for any two black holes, it is impossible to discern one twin from the other. Black holes, they say, have no hair.

    “In classical general relativity, they would be exactly identical,” said Paul Chesler, a theoretical physicist at Harvard University. “You can’t tell the difference.”

    Yet scientists have begun to wonder if the “no-hair theorem” is strictly true. In 2012, a mathematician named Stefanos Aretakis — then at the University of Cambridge (UK) and now at the University of Toronto (CA) — suggested that some black holes might have instabilities [Horizon Instability of Extremal Black Holes] on their event horizons. These instabilities would effectively give some regions of a black hole’s horizon a stronger gravitational pull than others. That would make otherwise identical black holes distinguishable [Physical Review Letters].

    However, his equations only showed that this was possible for so-called extremal black holes — ones that have a maximum value possible for either their mass, spin or charge. And as far as we know, “these black holes cannot exist, at least exactly, in nature,” said Chesler.

    But what if you had a near-extremal black hole, one that approached these extreme values but didn’t quite reach them? Such a black hole should be able to exist, at least in theory. Could it have detectable violations of the no-hair theorem?

    A paper published late last month [Physical Review D] shows that it could. Moreover, this hair could be detected by gravitational wave observatories.

    MIT /Caltech Advanced aLigo at Hanford, WA (US), Livingston, LA, (US) and VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    “Aretakis basically suggested there was some information that was left on the horizon,” said Gaurav Khanna, a physicist at the University of Massachusetts (US) and the University of Rhode Island (US) and one of the co-authors. “Our paper opens up the possibility of measuring this hair.”

    In particular, the scientists suggest that remnants either of the black hole’s formation or of later disturbances, such as matter falling into the black hole, could create gravitational instabilities on or near the event horizon of a near-extremal black hole. “We would expect that the gravitational signal we would see would be quite different from ordinary black holes that are not extremal,” said Khanna.

    If black holes do have hair — thus retaining some information about their past — this could have implications for the famous black hole information paradox put forward by the late physicist Stephen Hawking, said Lia Medeiros, an astrophysicist at the Institute for Advanced Study in Princeton, New Jersey (US). That paradox distills the fundamental conflict between general relativity and quantum mechanics, the two great pillars of 20th-century physics. “If you violate one of the assumptions [of the information paradox], you might be able to solve the paradox itself,” said Medeiros. “One of the assumptions is the no-hair theorem.”

    The ramifications of that could be broad. “If we can prove the actual space-time of the black hole outside of the black hole is different from what we expect, then I think that is going to have really huge implications for general relativity,” said Medeiros, who co-authored a paper in October [
    Physical Review Letters
    ] that addressed whether the observed geometry of black holes is consistent with predictions.

    Perhaps the most exciting aspect of this latest paper, however, is that it could provide a way to merge observations of black holes with fundamental physics. Detecting hair on black holes — perhaps the most extreme astrophysical laboratories in the universe — could allow us to probe ideas such as string theory and quantum gravity in a way that has never been possible before.

    “One of the big issues [with] string theory and quantum gravity is that it’s really hard to test those predictions,” said Medeiros. “So if you have anything that’s even remotely testable, that’s amazing.”

    There are major hurdles, however. It’s not certain that near-extremal black holes exist. (The best simulations at the moment typically produce black holes that are 30% away from being extremal, said Chesler.) And even if they do, it’s not clear if gravitational wave detectors would be sensitive enough to spot these instabilities from the hair.

    What’s more, the hair is expected to be incredibly short-lived, lasting just fractions of a second.

    But the paper itself, at least in principle, seems sound. “I don’t think that anybody in the community doubts it,” said Chesler. “It’s not speculative. It just turns out Einstein’s equations are so complicated that we’re discovering new properties of them on a yearly basis.”

    The next step would be to see what sort of signals we should be looking for in our gravitational detectors — either LIGO and Virgo, operating today, or future instruments like the European Space Agency’s space-based LISA instrument.

    Gravity is talking. Lisa will listen. Dialogos of Eide.


    ESA/NASA eLISA space based, the future of gravitational wave research.

    “One should now build upon their work and really compute what would be the frequency of this gravitational radiation, and understand how we could measure and identify it,” said Helvi Witek, an astrophysicist at the University of Illinois, Urbana-Champaign (US). “The next step is to go from this very nice and important theoretical study to what would be the signature.”

    There are plenty of reasons to want to do so. While the chances of a detection that would prove the paper correct are slim, such a discovery would not only challenge Einstein’s theory of general relativity but prove the existence of near-extremal black holes.

    “We would love to know if nature would even allow for such a beast to exist,” said Khanna. “It would have pretty dramatic implications for our field.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

     
  • richardmitnick 2:58 pm on February 11, 2021 Permalink | Reply
    Tags: "Hubble Uncovers Concentration of Small Black Holes", A gravitational pinball game takes place inside globular clusters., , , , Because a black hole cannot be seen they carefully studied the motion of stars inside the cluster., Black Hole science, , , Hubble researchers went hunting for an IMBH in the nearby globular cluster NGC 6397., Intermediate-mass black holes (IMBHs) have been elusive., , NGC 6397 is a core-collapsed cluster., The amount of mass a black hole can pack away varies widely from less than twice the mass of our Sun to over a billion times our Sun's mass., The central black holes may eventually merge sending ripples across space as gravitational waves., The study led to the conclusion that there is not just one hefty black hole but a swarm of smaller black holes – a mini-cluster in the core of the globular., This game of stellar pinball is called "dynamical friction" where heavier stars are segregated in the cluster's core and lower-mass stars migrate to the cluster's periphery.   

    From NASA/ESA Hubble Telescope: “Hubble Uncovers Concentration of Small Black Holes” 

    NASA/ESA Hubble Telescope


    From NASA/ESA Hubble Telescope

    February 11, 2021

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4514
    villard@stsci.edu

    Bethany Downer
    ESA/Hubble Space Telescope
    bethany.downer@esahubble.org

    Science Contacts:
    Eduardo Vitral
    Institut d’Astrophysique de Paris (IAP)(FR)
    vitral@iap.fr

    Dr. Gary A. Mamon
    Institut d’Astrophysique de Paris (IAP) (FR)
    gam@iap.fr

    1
    Compass Image for NGC 6397
    Credits: Image: NASA/ESA, T. Brown, S. Casertano, and J. Anderson (STScI) (US)
    Science: NASA/ ESA E. Vitral and G. Mamon (Institut d’Astrophysique de Paris (IAP) (FR)

    Summary

    The idea that black holes come in different sizes may sound a little odd at first. After all, a black hole by definition is an object that has collapsed under gravity to an infinite density, making it smaller than the period at the end of this sentence. But the amount of mass a black hole can pack away varies widely from less than twice the mass of our Sun to over a billion times our Sun’s mass. Midway between are intermediate-mass black holes (IMBHs) weighing roughly hundreds to tens of thousands of solar masses. So, black holes come small, medium, and large.

    However, the IMBHs have been elusive. They are predicted to hide out in the centers of globular star clusters, beehive-shaped swarms of as many as a million stars. Hubble researchers went hunting for an IMBH in the nearby globular cluster NGC 6397 and came up with a surprise. Because a black hole cannot be seen, they carefully studied the motion of stars inside the cluster, that would be gravitationally affected by the black hole’s gravitational tug. The amplitudes and shapes of the stellar orbits led to the conclusion that there is not just one hefty black hole, but a swarm of smaller black holes – a mini-cluster in the core of the globular.

    Why are the black holes hanging out together? A gravitational pinball game takes place inside globular clusters where more massive objects sink to the center by exchanging momentum with smaller stars, that then migrate to the cluster’s periphery. The central black holes may eventually merge, sending ripples across space as gravitational waves.

    ________________________________________________________________________________________________________

    Astronomers found something they weren’t expecting at the heart of the globular cluster NGC 6397: a concentration of smaller black holes lurking there instead of one massive black hole.

    Globular clusters are extremely dense stellar systems, which host stars that are closely packed together. These systems are also typically very old — the globular cluster at the focus of this study, NGC 6397, is almost as old as the universe itself. This cluster resides 7,800 light-years away, making it one of the closest globular clusters to Earth. Due to its very dense nucleus, it is known as a core-collapsed cluster.

    At first, astronomers thought the globular cluster hosted an intermediate-mass black hole (IMBH). These IMBHs are the long-sought “missing link” between supermassive black holes (many millions of times our Sun’s mass) that lie at the cores of galaxies, and stellar-mass black holes (a few times our Sun’s mass) that form following the collapse of a single massive star. Their mere existence is hotly debated. Only a few candidates have been identified to date.

    “We found very strong evidence for an invisible mass in the dense core of the globular cluster, but we were surprised to find that this extra mass is not ‘point-like’ (that would be expected for a solitary massive black hole) but extended to a few percent of the size of the cluster,” said Eduardo Vitral of the Paris Institute of Astrophysics, (IAP) (FR).

    To detect the elusive hidden mass, Vitral and Gary Mamon, also of IAP, used the velocities of stars in the cluster to determine the distribution of its total mass, that is the mass in the visible stars, as well as in faint stars and black holes. The more mass at some location, the faster the stars travel around it.

    The researchers used previous estimates of the stars’ tiny proper motions (their apparent motions on the sky), which allow for determining their true velocities within the cluster. These precise measurements for stars in the cluster’s core could only be made with Hubble over several years of observation. The Hubble data were added to well-calibrated proper motion measurements provided by the European Space Agency’s Gaia space observatory, but which are less precise than Hubble’s observations in the core.

    ESA (EU)/GAIA satellite .

    “Our analysis indicated that the orbits of the stars are close to random throughout the globular cluster, rather than systematically circular or very elongated,” explained Mamon. These moderate-elongation orbital shapes constrain what the inner mass must be.

    The researchers conclude that the invisible component can only be made of the remnants of massive stars (white dwarfs, neutron stars, and black holes) given its mass, extent and location. These stellar corpses progressively sank to the cluster’s center after gravitational interactions with nearby less massive stars. This game of stellar pinball is called “dynamical friction,” where, through an exchange of momentum, heavier stars are segregated in the cluster’s core and lower-mass stars migrate to the cluster’s periphery.

    “We used the theory of stellar evolution to conclude that most of the extra mass we found was in the form of black holes,” said Mamon. Two other recent studies had also proposed that stellar remnants, in particular, stellar-mass black holes, could populate the inner regions of globular clusters. “Ours is the first study to provide both the mass and the extent of what appears to be a collection of mostly black holes in the center of a core-collapsed globular cluster,” added Vitral [Astronomy & Astrophysics].

    The astronomers also note that this discovery raises the possibility that mergers of these tightly packed black holes in globular clusters may be an important source of gravitational waves, ripples through spacetime. Such phenomena could be detected by the LIGO (Laser Interferometer Gravitational-Wave Observatory) experiment. LIGO is funded by the National Science Foundation and operated by Caltech and MIT.

    MIT /Caltech Advanced aLigo .

    See the full article here.


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    Major Instrumentation

    Wide Field Camera 3 [WFC3]

    NASA/ESA Hubble WFC3

    Advanced Camera for Surveys [ACS]

    NASA Hubble Advanced Camera for Surveys.

    Cosmic Origins Spectrograph [COS]

    NASA Hubble Cosmic Origins Spectrograph.

    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

    ESA50 Logo large

     
  • richardmitnick 10:28 am on February 11, 2021 Permalink | Reply
    Tags: "Researchers gather numerical evidence of quantum chaos in the Sachdev-Ye-Kitaev model", , , , Black Hole science, Chaos in quantum systems composed of strongly interacting particles also known as “many-body chaos”, , , , ,   

    From UC Berkeley via phys.org: “Researchers gather numerical evidence of quantum chaos in the Sachdev-Ye-Kitaev model” 

    From UC Berkeley

    via


    phys.org

    February 11, 2021
    Ingrid Fadelli , Phys.org

    1
    A schematic phase diagram showing the behavior of the Sachdev-Ye-Kitaev model for different regimes of temperature and system size. From high to low temperature, the model transitions from behaving like interacting particles, to a semiclassical black hole, to a highly quantum black hole. Credit: Kobrin et al.

    Over the past few years, many physicists worldwide have conducted research investigating chaos in quantum systems composed of strongly interacting particles, also known as “many-body chaos”. The study of many-body chaos has broadened the current understanding of quantum thermalization (i.e., the process through which quantum particles reach thermal equilibrium by interacting with one another) and revealed surprising connections between microscopic physics and the dynamics of black holes.

    Researchers at University of California, Berkeley have recently carried out a study [Physical Review Letters] examining many-body chaos in the context of a renowned physical construct called the Sachdev-Ye-Kitaev (SYK) model. The SYK model describes a cluster of randomly interacting particles and was the first microscopic quantum system predicted to exhibit many-body chaos.

    “Our work is motivated by the fundamental question of how quickly information can spread in strongly-interacting quantum systems,” Bryce Kobrin, one of the researchers who carried out the study, told Phys.org. “A few years ago, a beautiful theoretical prediction emerged which suggested that in certain high-dimensional systems, information spreads exponentially fast, analogous to the butterfly effect in classical chaos.”

    In addition to hypothesizing this rapid spread of information in certain high-dimensional systems, previous studies proved that there is a universal speed limit on the rate at which this ‘chaos’ can develop. Interestingly, the only known or hypothesized systems that reach this limit are closely related to black holes, or more specifically, quantum theories that describe black holes. A major surprise was when researchers predicted that the SYK model also saturates the universal bound on chaos. This insight led to further analyses indicating that the low-temperature properties of the SYK model are, in effect, equivalent to that of a charged black hole.

    Although these ideas have been supported by theoretical calculations, verifying their validity and observing quantum chaos in numerical simulations has so far proved to be an enduring challenge. Kobrin and his colleagues set out to investigate the chaotic nature of the SYK model. They did this by simulating the dynamics of exceptionally large systems using cutting-edge numerical techniques they developed. Subsequently, they analyzed the data they collected using a method based on calculations from quantum gravity.

    “As a function of temperature, we observed the system change from behaving like ordinary interacting particles to agreeing precisely with the predicted behavior of a quantum black hole,” Kobrin said. “By developing new procedures to analyze our results, we determined the rate of chaos and explicitly showed that, at low temperatures, it approached the theoretical upper bound.”

    Kobrin and his colleagues gathered direct numerical evidence of a new dynamical phenomenon, namely many-body chaos, which translates chaos from classical mechanics to strongly interacting quantum systems. Their findings also highlight the valuable interplay between quantum simulations and quantum gravity theories.

    While in their recent study the researchers used the numerical tools that they created to examine many-body chaos in the SYK model in the future the same techniques could be applied to other models that are difficult to examine using common analysis frameworks. Ultimately, this could aid the ongoing search for quantum systems that exhibit the same behavior as black holes. Finally, the methods employed by this team of researchers could also inspire the development of experimental techniques to simulate quantum dynamics on controllable quantum hardware, for instance using arrays of cold atoms or trapped ions.

    “I am excited to investigate other phenomena at the intersection between quantum information and quantum gravity,” Kobrin said. “For example, it is predicted that by coupling together two copies of the SYK model, one can form a so-called traversable wormhole through which information can be communicated. This is a highly counterintuitive result which demonstrates that quantum chaos can, in fact, help move information from one place to another.”

    See the full article here .

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    Please help promote STEM in your local schools.

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    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

    UC Berkeley Seal

     
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