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  • richardmitnick 7:27 pm on July 10, 2021 Permalink | Reply
    Tags: , , Dark Matter Background: Fritz Zwicky and Vera Rubin, Dark Matter is one of the most vexing known unknowns in nature., Dark Matter makes up about 85% of the mass in the universe., In addition to dark matter hidden dark forces may govern dark matter’s interactions., , ,   

    From University of California-Riverside (US) : “A new dimension in the quest to understand dark matter” 

    UC Riverside bloc

    From University of California-Riverside (US)

    June 2, 2021 [Just now in social media.]
    Iqbal Pittalwala

    As its name suggests, Dark Matter — material which makes up about 85% of the mass in the universe — emits no light, eluding easy detection. Its properties, too, remain fairly obscure.

    Now, a theoretical particle physicist at the University of California, Riverside, and colleagues have published a research paper in the Journal of High Energy Physics that shows how theories positing the existence a new type of force could help explain dark matter’s properties.

    1
    Flip Tanedo

    “We live in an ocean of Dark Matter, yet we know very little about what it could be,” said Flip Tanedo, an assistant professor of physics and astronomy and the paper’s senior author. “It is one of the most vexing known unknowns in nature. We know it exists, but we do not know how to look for it or why it hasn’t shown up where we expected it.”

    2
    Photo shows Flip Tanedo (left), Sylvain Fichet (center), and Hai-Bo Yu. Credit: Flip Tanedo/UCR.

    Physicists have used telescopes, gigantic underground experiments, and colliders to learn more about dark matter for the last 30 years, though no positive evidence has materialized. The negative evidence, however, has forced theoretical physicists like Tanedo to think more creatively about what dark matter could be.

    The new research, which proposes the existence of an extra dimension in space-time to search for dark matter, is part of an ongoing research program at UC Riverside led by Tanedo. According to this theory, some of the dark matter particles don’t behave like particles. In effect, invisible particles interact with even more invisible particles in such a way that the latter cease to behave like particles.

    “The goal of my research program for the past two years is to extend the idea of dark matter ‘talking’ to dark forces,” Tanedo said. “Over the past decade, physicists have come to appreciate that, in addition to dark matter hidden dark forces may govern dark matter’s interactions. These could completely rewrite the rules for how one ought to look for dark matter.”

    If two particles of dark matter are attracted to, or repelled by, each other, then dark forces are operating. Tanedo explained that dark forces are described mathematically by a theory with extra dimensions and appear as a continuum of particles that could address puzzles seen in small galaxies.

    “Our ongoing research program at UCR is a further generalization of the dark force proposal,” he said. “Our observed universe has three dimensions of space. We propose that there may be a fourth dimension that only the dark forces know about. The extra dimension can explain why dark matter has hidden so well from our attempts to study it in a lab.”

    Tanedo explained that although extra dimensions may sound like an exotic idea, they are actually a mathematical trick to describe “conformal field theories” — ordinary three-dimensional theories that are highly quantum mechanical. These types of theories are mathematically rich, but do not contain conventional particles and so are typically not considered to be relevant for describing nature. The mathematical equivalence between these challenging three-dimensional theories and a more tractable extra dimensional theory is known as the holographic principle.

    “Since these conformal field theories were both intractable and unusual, they hadn’t really been systematically applied to dark matter,” Tanedo added. “Instead of using that language, we work with the holographic extra-dimensional theory.”

    The key feature of the extra-dimensional theory is that the force between dark matter particles is described by an infinite number of different particles with different masses called a continuum. In contrast, ordinary forces are described by a single type of particle with a fixed mass. This class of continuum-dark sectors is exciting to Tanedo because it does something “fresh and different.”

    According to Tanedo, past work on dark sectors focuses primarily on theories that mimic the behavior of visible particles. His research program is exploring the more extreme types of theories that most particle physicists found less interesting, perhaps because no analogs exist in the real world.

    In Tanedo’s theory, the force between dark matter particles is surprisingly different from the forces felt by ordinary matter.

    “For the gravitational force or electric force that I teach in my introductory physics course, when you double the distance between two particles you reduce the force by a factor of four. A continuum force, on the other hand, is reduced by a factor of up to eight.”

    What implications does this extra dimensional dark force have? Since ordinary matter may not interact with this dark force, Tanedo turned to the idea of self-interacting dark matter [Physical Review Letters], an idea pioneered by Hai-Bo Yu, an associate professor of physics and astronomy at UCR who is not a coauthor on the paper. Yu showed that even in the absence of any interactions with normal matter, the effects of these dark forces could be observed indirectly in dwarf spheroidal galaxies. Tanedo’s team found the continuum force can reproduce the observed stellar motions.

    “Our model goes further and makes it easier than the self-interacting dark matter model to explain the cosmic origin of dark matter,” Tanedo said.

    Next, Tanedo’s team will explore a continuum version of the “dark photon” model.

    “It’s a more realistic picture for a dark force,” Tanedo said. “Dark photons have been studied in great detail, but our extra-dimensional framework has a few surprises. We will also look into the cosmology of dark forces and the physics of black holes.”

    Tanedo has been working diligently on identifying “blind spots” in his team’s search for dark matter.

    “My research program targets one of the assumptions we make about particle physics: that the interaction of particles is well-described by the exchange of more particles,” he said. “While that is true for ordinary matter, there’s no reason to assume that for dark matter. Their interactions could be described by a continuum of exchanged particles rather than just exchanging a single type of force particle.”

    Tanedo was joined in the research by Ian Chaffey, a postdoctoral researcher working with Tanedo; and Sylvain Fichet, a postdoctoral researcher at the International Center for Theoretical Physics – South American Institute for Fundamental Research [Instituto sul-Americano de Pesquisa Fundamental](BR).

    The research was funded by the U.S. Department of Energy.

    ______________________________________________________________________________________________________________

    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 Axion Dark Matter eXperiment U Washington (US) Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.
    _____________________________________________________________________________________

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    [caption id="attachment_33275" align="alignnone" width="632"] 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 University of California-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-Los Angeles, 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 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 UC-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. 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 UC-Riverside 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 University of California 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 11:59 am on June 13, 2021 Permalink | Reply
    Tags: " 'Sterile neutrinos' may be portal to the dark side", “BeEST”: “Beryllium Electron-capture with Superconducting Tunnel junctions.”, , , Dark Matter Background: Fritz Zwicky and Vera Rubin, , , Using nuclear decay in high-rate quantum sensors in the search for "sterile neutrinos".   

    From DOE’s Lawrence Livermore National Laboratory (US) : “Sterile neutrinos may be portal to the dark side” 

    From DOE’s Lawrence Livermore National Laboratory (US)

    4.27.21 [Just now in social media.]

    Anne M Stark
    stark8@llnl.gov
    925-422-9799

    1
    Schematic of the “BeEST” experiment. Radioactive beryllium-7 is implanted into the superconducting sensor. Precision measurements of the decay products could indicate the presence of hypothesized “sterile neutrinos”.

    “Sterile neutrinos” are theoretically predicted new particles that offer an intriguing possibility in the quest for understanding the Dark Matter in our universe.

    Unlike the known “active” neutrinos in the Standard Model (SM) of Particle Physics, these sterile neutrinos do not interact with normal matter as they move through space, making them very difficult to detect.

    A team of interdisciplinary researchers, led by Lawrence Livermore National Laboratory (LLNL) and the Colorado School of Mines (US), has demonstrated the power of using nuclear decay in high-rate quantum sensors in the search for sterile neutrinos. The findings are the first measurements of their kind.

    The research has been featured recently as a DOE Office of Science Highlight and will jump-start an extended project to look for one of the most promising candidates for dark matter, the strange unidentified material that permeates the universe and accounts for 85 percent of its total mass.

    The experiment involves implanting radioactive beryllium-7 atoms into superconducting sensors developed at LLNL and has been nicknamed the “BeEST” for “Beryllium Electron-capture with Superconducting Tunnel junctions.” When the beryllium-7 decays by electron capture into lithium-7 and a neutrino, the neutrino escapes from the sensor, but the recoil energy of the lithium-7 provides a measure of the neutrino mass. If a heavy sterile neutrino with mass mc^2 were to be generated in a faction of the decays, the lithium-7 recoil energy would be reduced and produce a measurable signal, even though the elusive neutrino itself is not detected directly.

    With a measurement time of just 28 days using a single sensor, the data excludes the existence of sterile neutrinos in the mass range of 100 to 850 kiloelectronvolts down to a 0.01 percent level of mixing with the active neutrinos — better than all previous decay experiments in this range. In addition, simulations on LLNL supercomputers have helped the team understand some of the materials effects in the detector that need to be accounted for to gain confidence in potential sterile neutrino detection events.

    “This research effort lays the groundwork for even more powerful searches for these new particles using large arrays of sensors with new superconducting materials,” said LLNL scientist Stephan Friedrich, lead author of the research appearing in Physical Review Letters.

    The Standard Model of Particle Physics is one of the crowning achievements in modern science and the cornerstone of current subatomic studies. Despite its success, the SM is known to be incomplete, and physics beyond the Standard Model (BSM) is required to develop a full description of the universe. The neutrino sector offers an intriguing avenue for BSM physics as the observation of nonzero neutrino masses currently provides the only confirmed violation of the SM as it was originally constructed.

    “Sterile neutrinos are exciting because they are strong candidates for so-called ‘warm’ dark matter, and they also may help to address the origin of the matter-antimatter asymmetry of the universe,” Friedrich said.

    Other LLNL authors include Geonbo Kim, Vincenzo Lordi and Amit Samanta.

    This research is funded by the Laboratory Directed Research and Development program.

    _____________________________________________________________________________________

    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.


    _____________________________________________________________________________________

    Dark Matter Research

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration

    DOE’s Lawrence Livermore National Laboratory (LLNL) (US) is an American federal research facility in Livermore, California, United States, founded by the University of California-Berkeley (US) in 1952. A Federally Funded Research and Development Center (FFRDC), it is primarily funded by the U.S. Department of Energy (DOE) and managed and operated by Lawrence Livermore National Security, LLC (LLNS), a partnership of the University of California, Bechtel, BWX Technologies, AECOM, and Battelle Memorial Institute in affiliation with the Texas A&M University System (US). In 2012, the laboratory had the synthetic chemical element livermorium named after it.
    LLNL is self-described as “a premier research and development institution for science and technology applied to national security.” Its principal responsibility is ensuring the safety, security and reliability of the nation’s nuclear weapons through the application of advanced science, engineering and technology. The Laboratory also applies its special expertise and multidisciplinary capabilities to preventing the proliferation and use of weapons of mass destruction, bolstering homeland security and solving other nationally important problems, including energy and environmental security, basic science and economic competitiveness.

    The Laboratory is located on a one-square-mile (2.6 km^2) site at the eastern edge of Livermore. It also operates a 7,000 acres (28 km2) remote experimental test site, called Site 300, situated about 15 miles (24 km) southeast of the main lab site. LLNL has an annual budget of about $1.5 billion and a staff of roughly 5,800 employees.

    LLNL was established in 1952 as the University of California Radiation Laboratory at Livermore, an offshoot of the existing UC Radiation Laboratory at Berkeley. It was intended to spur innovation and provide competition to the nuclear weapon design laboratory at Los Alamos in New Mexico, home of the Manhattan Project that developed the first atomic weapons. Edward Teller and Ernest Lawrence, director of the Radiation Laboratory at Berkeley, are regarded as the co-founders of the Livermore facility.

    The new laboratory was sited at a former naval air station of World War II. It was already home to several UC Radiation Laboratory projects that were too large for its location in the Berkeley Hills above the UC campus, including one of the first experiments in the magnetic approach to confined thermonuclear reactions (i.e. fusion). About half an hour southeast of Berkeley, the Livermore site provided much greater security for classified projects than an urban university campus.

    Lawrence tapped 32-year-old Herbert York, a former graduate student of his, to run Livermore. Under York, the Lab had four main programs: Project Sherwood (the magnetic-fusion program), Project Whitney (the weapons-design program), diagnostic weapon experiments (both for the DOE’s Los Alamos National Laboratory(US) and Livermore laboratories), and a basic physics program. York and the new lab embraced the Lawrence “big science” approach, tackling challenging projects with physicists, chemists, engineers, and computational scientists working together in multidisciplinary teams. Lawrence died in August 1958 and shortly after, the university’s board of regents named both laboratories for him, as the Lawrence Radiation Laboratory.

    Historically, the DOE’s Lawrence Berkeley National Laboratory (US) and Livermore laboratories have had very close relationships on research projects, business operations, and staff. The Livermore Lab was established initially as a branch of the Berkeley laboratory. The Livermore lab was not officially severed administratively from the Berkeley lab until 1971. To this day, in official planning documents and records, Lawrence Berkeley National Laboratory is designated as Site 100, Lawrence Livermore National Lab as Site 200, and LLNL’s remote test location as Site 300.

    The laboratory was renamed Lawrence Livermore Laboratory (LLL) in 1971. On October 1, 2007 LLNS assumed management of LLNL from the University of California, which had exclusively managed and operated the Laboratory since its inception 55 years before. The laboratory was honored in 2012 by having the synthetic chemical element livermorium named after it. The LLNS takeover of the laboratory has been controversial. In May 2013, an Alameda County jury awarded over $2.7 million to five former laboratory employees who were among 430 employees LLNS laid off during 2008.The jury found that LLNS breached a contractual obligation to terminate the employees only for “reasonable cause.” The five plaintiffs also have pending age discrimination claims against LLNS, which will be heard by a different jury in a separate trial.[6] There are 125 co-plaintiffs awaiting trial on similar claims against LLNS. The May 2008 layoff was the first layoff at the laboratory in nearly 40 years.

    On March 14, 2011, the City of Livermore officially expanded the city’s boundaries to annex LLNL and move it within the city limits. The unanimous vote by the Livermore city council expanded Livermore’s southeastern boundaries to cover 15 land parcels covering 1,057 acres (4.28 km^2) that comprise the LLNL site. The site was formerly an unincorporated area of Alameda County. The LLNL campus continues to be owned by the federal government.

    LLNL/NIF

    DOE Seal

    NNSA

     
  • richardmitnick 2:59 pm on February 2, 2021 Permalink | Reply
    Tags: "Astronomers detect extended dark matter halo around ancient dwarf galaxy", , , , , Dark Matter Background: Fritz Zwicky and Vera Rubin, Dark matter halo — a region of gravitationally bound matter ., Dark Matter is a crucial ingredient in making a galaxy and holding it together., , The ancient galaxy may have been the product of one of the first mergers in the universe between two infant galaxies-one slightly less primitive than the other., The Milky Way is surrounded by dozens of dwarf galaxies that are thought to be relics of the very first galaxies in the universe., The very first galaxies in the universe were also likely extended and more massive than previously thought., Tucana II is one of the most primitive dwarf galaxies known based on the metal content of its stars., Tucana II ultra-faint dwarf galaxy, Tucana II will eventually be eaten by the Milky Way no mercy., Without dark matter galaxies would just fly apart.   

    From MIT: “Astronomers detect extended dark matter halo around ancient dwarf galaxy” 

    MIT News

    From MIT News

    February 1, 2021
    Jennifer Chu

    1
    The vicinity of the Tucana II ultra-faint dwarf galaxy, as imaged with the SkyMapper Telescope. Credit: Anirudh Chiti, MIT.


    ANU Skymapper telescope, a fully automated 1.35 m (4.4 ft) wide-angle optical telescope, at Siding Spring Observatory , near Coonabarabran, New South Wales, Australia, Altitude 1,165 m (3,822 ft)

    The Milky Way is surrounded by dozens of dwarf galaxies that are thought to be relics of the very first galaxies in the universe. Among the most primitive of these galactic fossils is Tucana II — an ultrafaint dwarf galaxy that is about 50 kiloparsecs, or 163,000 light years, from Earth.

    Now MIT astrophysicists have detected stars at the edge of Tucana II, in a configuration that is surprisingly far from its center but nevertheless caught up in the tiny galaxy’s gravitational pull. This is the first evidence that Tucana II hosts an extended dark matter halo — a region of gravitationally bound matter that the researchers calculated to be three to five times more massive than scientists had estimated.

    Caterpillar Project A Milky-Way-size dark-matter halo and its subhalos circled, an enormous suite of simulations . Griffen et al. 2016.

    This discovery of far-flung stars in an ancient dwarf galaxy implies that the very first galaxies in the universe were also likely extended and more massive than previously thought.

    “Tucana II has a lot more mass than we thought, in order to bound these stars that are so far away,” says MIT graduate student Anirudh Chiti. “This means that other relic first galaxies probably have these kinds of extended halos too.”

    The researchers also determined that the stars on the outskirts of Tucana II are more primitive than the stars at the galaxy’s core. This is the first evidence of such a stellar imbalance in an ultrafaint dwarf galaxy.

    The unique configuration suggests that the ancient galaxy may have been the product of one of the first mergers in the universe, between two infant galaxies — one slightly less primitive than the other.

    “We may be seeing the first signature of galactic cannibalism,” says Anna Frebel, the Silverman Family Career Development Associate Professor of Physics at MIT. “One galaxy may have eaten one of its slightly smaller, more primitive neighbors, that then spilled all its stars into the outskirts.”

    Frebel, Chiti, and their colleagues have published their results today in Nature Astronomy.

    Not-so-wimpy galaxies

    Tucana II is one of the most primitive dwarf galaxies known, based on the metal content of its stars. Stars with low metal content likely formed very early on, when the universe was not yet producing heavy elements. In the case of Tucana II, astronomers had previously identified a handful of stars around the galaxy’s core with such low metal content that the galaxy was deemed the most chemically primitive of the known ultrafaint dwarf galaxies.

    Chiti and Frebel wondered whether the ancient galaxy might harbor other, even older stars, that might shed light on the formation of the universe’s first galaxies. To test this idea, they obtained observations of Tucana II through the SkyMapper Telescope, an optical ground-based telescope in Australia that takes in wide views of the southern sky.

    The team used an imaging filter on the telescope to spot primitive, metal-poor stars beyond the galaxy’s core. The team ran an algorithm, developed by Chiti, through the filtered data to efficiently pick out stars with low metal content, including the previously identified stars at the center and nine new stars much further out from the galactic core.

    “Ani’s analysis shows a kinematic conection, that these far-out stars move in lockstep with the inner stars, like bathwater going down the drain,” Frebel adds.

    The results suggest that Tucana II must have an extended dark matter halo that is three to five times more massive than previously thought, in order for it to keep a gravitational hold on these far-off stars. Dark matter is a hypothetical type of matter that is thought to make up more than 85 percent of the universe. Every galaxy is thought to be held together by a local concentration, or halo, of dark matter.

    “Without dark matter, galaxies would just fly apart,” Chiti. says. Dark Matter is a crucial ingredient in making a galaxy and holding it together.”

    The team’s results are the first evidence that an ultrafaint dwarf galaxy can harbor an extended dark matter halo.

    “This probably also means that the earliest galaxies formed in much larger dark matter halos than previously thought,” Frebel says. “We have thought that the first galaxies were the tiniest, wimpiest galaxies. But they actually may have been several times larger than we thought, and not so tiny after all.”

    “A cannibalistic history”

    Chiti and Frebel followed up their initial results with observations of Tucana II taken by the Magellan Telescopes in Chile.

    Carnegie 6.5 meter Magellan Baade and Clay Telescopes located at Carnegie’s Las Campanas Observatory, Chile. over 2,500 m (8,200 ft) high.

    With Magellan, the team focused in on the galaxy’s metal-poor stars to derive their relative metallicities, and discovered the outer stars were three times more metal-poor, and therefore more primitive, than those at the center.

    “This is the first time we’ve seen something that looks like a chemical difference between the inner and outer stars in an ancient galaxy,” Chiti says.

    A likely explanation for the imbalance may be an early galactic merger, in which a small galaxy — possibly among the first generation of galaxies to form in the universe — swallowed another nearby galaxy. This galactic cannibalism occurs constantly throughout the universe today, but it was unclear whether early galaxies merged in a similar way.

    “Tucana II will eventually be eaten by the Milky Way, no mercy,” Frebel says. “And it turns out this ancient galaxy may have its own cannibalistic history.”

    The team plans to use their approach to observe other ultrafaint dwarf galaxies around the Milky Way, in hopes of discovering even older, farther-flung stars.

    “There are likely many more systems, perhaps all of them, that have these stars blinking in their outskirts,” Frebel says.

    This research was supported, in part, by NASA and the National Science Foundation.

    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).

    See the full article here .

    See also the article from Carnegie Institution for Science here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    MIT Seal

    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

    USPS “Forever” postage stamps celebrating Innovation at MIT.

    MIT Campus

     
  • richardmitnick 12:07 pm on January 25, 2021 Permalink | Reply
    Tags: "Precision Cosmology", , , , , , Dark Matter Background: Fritz Zwicky and Vera Rubin,   

    From Kavli Institute for Cosmology- Cambridge (UK): “Precision Cosmology” 

    KavliFoundation

    The Kavli Foundation

    From Kavli Institute for Cosmology, Cambridge (UK)

    12/21/2020 [Just now in social media.]
    Adam Hadhazy

    1
    Researchers continue to make refinements to the measurements and observations that are revealing the universe’s constituent substances and their interactions. Artist impression of Euclid spacecraft, Credit: ESA/ATG medialab (spacecraft); NASA, ESA, CXC, C. Ma, H. Ebeling and E. Barrett (University of Hawaii/IfA), et al. and STScI (background).

    As a science, cosmology is as big as it gets. Ambitiously, the field concerns itself with the entire universe, as well as all of time. When dealing with these sorts of colossal spans, “precision” would appear to be unachievable, or even almost beside the point; merely ballparking why and how things are the way they are might seem explanatorily satisfying.

    The approach of so-called precision cosmology belies this notion, however. Precision cosmology is premised on continuing to nail down the various parameters that have worked in concert to determine the structure of the universe over its eons of existence—along with all the eons to come.

    This is the essence of one of the research themes at the Kavli Institute for Cosmology, Cambridge (KICC), “Large Scale Structure and Precision Cosmology.” The theme emerges from ever-advancing work detailing the interplay of three entities, namely matter, dark matter, and dark energy. These entities have determined the look, shape, and evolution of the cosmos, based on physical laws and their large-scale manifestations.

    Of the trio, matter is the one we’re deeply familiar, though it only evidently makes up about five percent of the whole cosmic kit ‘n kaboodle. Dark Matter has haunted cosmologists for decades, lurking as an unseeable, but indirectly detectable sort of gravitational glue that holds individual galaxies and vast, galaxy-studded cosmic structures together. It’s reckoned to compose a quarter of the universe’s total substance. The last of the three entities, dark energy, comprises the cosmic lion’s share, about 70 percent. Remarkably, Dark Energy was only discovered in the late 1990s, revealed through supernovae explosions of stars that appeared far too faint, given their expected distance. These observations startlingly revealed that the universe’s documented expansion is accelerating.

    “This discovery marked a paradigm shift: the density of the Universe was dominated by a new component—dark energy—in addition to dark matter,” says George Efstathiou, former director and current member of KICC, as well as Professor of Astrophysics (1909) at the University of Cambridge. “However, we didn’t know the densities of these components to any great precision.”

    Efstathiou is one of the researchers involved in the Large Scale Structure and Precision Cosmology theme at KICC. His work, alongside that of colleagues, has continued to constrain the properties of dark matter and dark energy, figuring out how they interact with all the aspects of the universe we can readily observe. The above-mentioned figures of 25 and 70 percent for dark matter and dark energy, respectively, stem directly from these field-wide efforts.

    “In the 20 years since this discovery [of dark energy], principally from observations of the cosmic microwave background radiation, large galaxy surveys and distant supernovae, the densities of these components has been measured accurately,” says Efstathiou.

    Cosmic Background Radiation per ESA/Planck

    The cosmic microwave background, or CMB, is often described as the oldest light in the universe.

    CMB per ESA/Planck.

    Delicate, yet detectable signals imprinted upon this light speak to the proportions of matter, dark matter, and dark energy, and how they’ve driven the universe’s evolution from the Big Bang to present day, 13.8 billion years later. The Planck spacecraft, which operated from 2009 to 2013, delivered the most precise CMB measurements to date.

    ESA/Planck 2009 to 2013

    But various observatories are continuing to delve further into this sky-wide glow, peeling back layers and delivering fresh insights.

    Large galaxy surveys, meanwhile, have likewise continued apace, through numerous projects, some with Kavli Institute involvement. Examples include the Dark Energy Survey, the Legacy Survey of Space and Time to be performed by the Vera C. Rubin observatory, and the galaxy-distance-measuring Euclid spacecraft slated for next decade.

    NOIRLab Vera C. Rubin Observatory Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes, altitude 2,715 m (8,907 ft).

    “Euclid will produce a very deep imaging survey,” says Efstathiou. “Euclid should also lead to precise measurements of the equation of state of dark energy.”

    Identifying and accounting for inevitable sources of error in measurements from necessarily imperfect instruments will be a significant challenge as researchers forge ahead into still-more-precise precision cosmology. So, too, will the increasingly pertinent nuances of the phenomena under study. “The main problem for the future will be dealing with systematic errors and astrophysical complexities,” says Efstathiou.

    Bit by bit, the whole picture of the cosmos is coming together, though entirely new physics may yet need to be invoked for it all to come into sharp focus. Precision is indeed possible, even on the grandest of scales. ​

    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.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOIRLab NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Kavli Institute for Cosmology, Cambridge (UK)

    For centuries, the University of Cambridge (UK) has been pushing back the frontiers of knowledge about the Universe. Joining this rich tradition of inquiry is the Kavli Institute for Cosmology, founded in 2006 as the first member of the Kavli network in the UK.

    Cambridge’s long history as a center for astronomy and cosmology includes Isaac Newton’s discovery of the law of gravitation and, in modern times, the discovery of pulsars and crucial contributions to the development of the Big Bang model of the Universe. The Kavli Institute is helping to continue this work by creating a single site at which the University’s cosmologists and astrophysicists from different academic departments can share knowledge and work together on major projects. In particular, KICC brings together scientists from the University’s Institute of Astronomy, the Cavendish Laboratory (the Department of Physics) and the Department of Applied Mathematics and Theoretical Physics.

    The Institute started operations in 2008, thanks to an endowment from the Kavli Foundation, and now has about 50 researchers working on the following themes:

    Cosmic Microwave Background and the Early Universe
    Large Scale Structures and Precision Cosmology
    Epoch of Cosmic Reionization
    Formation and Evolution of Galaxies and Supermassive Black Holes
    Evolution of the Intergalactic Medium
    Gravitational Waves
    The institute offers these scientists the benefit of close interaction as well as advanced technologies, including access to giant telescopes and space satellites. Meanwhile, the Institute’s fellowships program host promising scholars from around the globe for stays of up to five years. They are free to pursue their own independent research as well as taking part in the world-class flagship projects led by distinguished Cambridge scientists.

    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 8:18 pm on August 14, 2020 Permalink | Reply
    Tags: , , , , , , Dark Matter Background: Fritz Zwicky and Vera Rubin   

    From AAS NOVA: “When Dark Matter Gets Fuzzy” 

    AASNOVA

    From AAS NOVA

    14 August 2020
    Susanna Kohler

    1
    This composite image reveals the central region of our galaxy at X-ray (green and blue) and radio (red) wavelengths. A new study uses the Central Molecular Zone to constrain dark matter models. [X-Ray:NASA/CXC/UMass/D. Wang et al.; Radio:NRF/SARAO/MeerKAT]

    NASA/Chandra X-ray Telescope

    SKA SARAO Meerkat telescope(s), 90 km outside the small Northern Cape town of Carnarvon, SA

    What model of Dark Matter best describes our universe? A new study uses a unique region in our own galaxy to constrain one particular model: that of fuzzy dark matter.

    2
    There are many models describing the composition and behavior of dark matter, and how its evolution has affected the structure of our universe. [AMNH]

    Observations of our universe tell us that only 15% of the universe’s matter is the ordinary baryonic matter that we’re able to see. The remaining 85% is dark matter — mysterious material that has shaped the structure and evolution of our universe via its gravitational interactions, but that doesn’t give off any light.

    Because we can’t directly observe it, dark matter is still a relative unknown — and there are many different hypothesized models that describe its nature. Is dark matter hot? Cold? Composed of subatomic particles? Or macroscopic objects like primordial black holes? There’s a model for all of these options, and the best way to test them is to compare their predictions to the actual structure that we observe.

    Constraints from an Odd Structure

    One such constraining structure is a unique region in our own galaxy: the Central Molecular Zone, or CMZ. This extremely dense, rich collection of orbiting molecular gas lies in the very center of the Milky Way and spans just a few hundred light-years in diameter. Observations suggest that the molecular gas clouds orbit in a ring or a disk with a twisted 3D shape, but the thick dust that shrouds the galactic center limits what we can learn about the CMZ directly.

    3
    Plot of gas surface density from a simulation showing the formation of the CMZ — seen as the high-density gas ring at the heart of the plot — in the center of the Milky Way. This simulation included a nuclear bulge only, with no dark-matter core from the fuzzy dark matter model. [Li et al. 2020]

    The CMZ’s shape is not its only mystery, however: we also don’t fully understand what caused this odd structure to develop. Past studies of the birth of our galaxy’s structure from a thin disk suggest that formation of the CMZ relies on a combination of the Milky Way’s barred gravitational potential and an especially dense nuclear region.

    In a new publication led by Zhi Li (Shanghai Jiao Tong University, China), a team of scientists has now used this picture to constrain a dark matter model that relies on light dark-matter particles concentrated at the center of the galaxy.

    Adding Fuzziness to the Milky Way

    4
    Zoomed-in plot of gas surface density from a simulation showing the formation of the CMZ in the center of the Milky Way. This simulation included both a nuclear bulge and a dark-matter core from the fuzzy dark matter model. [Adapted from Li et al. 2020]

    Li and collaborators conduct a series of cosmological simulations that model the formation of the Milky Way from a thin disk in a realistic gravitational potential. In some of these simulations, the authors include only a dense nuclear bulge at the center of the galaxy. In others, they also add a galaxy core consistent with the predictions of fuzzy dark matter, a model that describes the universe’s dark matter as very light bosons that exhibit wave behavior on some scales.

    The authors show that the structure and dynamics of the CMZ can be reproduced well with only an exceedingly compact nuclear bulge. But the combination of a smaller nuclear bulge and a fuzzy-dark-matter core also neatly reproduces observations, leaving the door open for this dark-matter model.

    So is our dark matter fuzzy or not? We can’t tell yet, but Li and collaborators outline some future observations — like pinning down the mass-to-light ratio in the galactic center — that will help us answer this question and better understand what’s going on with that invisible 85% of our universe’s matter.

    Citation

    “Testing the Prediction of Fuzzy Dark Matter Theory in the Milky Way Center,” Zhi Li et al 2020 ApJ 889 88.

    https://iopscience.iop.org/article/10.3847/1538-4357/ab6598

    _______________________________________________________________

    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, 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

    The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    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

     
  • richardmitnick 12:30 pm on August 2, 2020 Permalink | Reply
    Tags: "An Alternative to Dark Matter Passes Critical Test", , , , , , Dark Matter Background: Fritz Zwicky and Vera Rubin, , ,   

    From Quanta Magazine via Nautilus: “An Alternative to Dark Matter Passes Critical Test” 

    From Quanta Magazine

    Via

    Nautilus

    July 2020
    Charlie Wood

    1
    A view of the center of the Milky Way galaxy. Theories of modified gravity have had a hard time describing the universe from relatively small scales like this all the way up to the scale of the universe as a whole. Credit: NASA/JPL-Caltech/ESA/CXC/STScI

    For decades, a band of rebel theorists has waged war with one of cosmology’s core concepts—the idea that an invisible, intangible form of matter forms the universe’s primary structure. This Dark Matter [see below, “Dark Matter Background” ], which seems to outweigh the stuff we’re made of 5-to-1, accounts for a host of observations: the tight cohesion of galaxies and packs of galaxies, the way light from faraway galaxies will bend on its way to terrestrial telescopes, and the mottled structure of the early universe, to name a few.

    The would-be revolutionaries seek an alternative cosmic recipe. In place of dark matter, they substitute a subtly modified force of gravity. But attempts to translate their rough idea into precise mathematical language have always run afoul of at least one key observation. Some formulations get galaxies right, some get the contortion of light rays right, but none have pierced dark matter’s most bulletproof piece of evidence: precise maps of ancient light, known as the cosmic microwave background (CMB).

    CMB per ESA/Planck

    ESA/Planck 2009 to 2013

    “A theory must do really well to agree with this data,” said Ruth Durrer, a cosmologist at the University of Geneva. “This is the bottleneck.”

    Now, two theorists say they’ve finally squeezed an alternative theory of gravity past that obstacle. Their work, which was posted online [“A new relativistic theory for Modified Newtonian Dynamics” ( https://arxiv.org/abs/2007.00082 )] in late June 2020 and has not yet passed peer review, uses a tweaked version of Einstein’s theory of gravity to reproduce an iconic map of the early universe, a feat that even some rebels feared to be impossible. “For 15 years we’ve just been dead in the water,” said Stacy McGaugh, an astronomer at Case Western Reserve University and a longtime advocate for modified-gravity theories who was not involved in the research. “It’s a huge leap forward.”

    Others agree that the model’s preliminary results appear promising. “It’s a bit baroque, but since nothing else has worked so far, I’m still impressed that it seems to work,” Durrer said.

    Most cosmologists still prefer dark matter as the simpler of the two paradigms, but they agree that the new theory could be intriguing—if it can truly match additional cosmological observations. “That would be a big barrier,” said Dan Hooper, an astrophysicist at the University of Chicago. “That would be pretty interesting.”

    Threading the Needle

    The challenges for alternative gravity theories, collectively known as modified Newtonian dynamics or MOND, were spelled out in a separate preprint [“What is the price of abandoning dark matter? Cosmological constraints on alternative gravity theories” ( https://arxiv.org/abs/2007.00555 ) ] coincidentally published the day after the latest model appeared.

    Mordehai Milgrom, MOND theorist, is an Israeli physicist and professor in the department of Condensed Matter Physics at the Weizmann Institute in Rehovot, Israel http://cosmos.nautil.us

    MOND Rotation Curves with MOND Tully-Fisher

    MOND Modified Newtonian Dynamics a Humble Introduction Marcus Nielbock

    MOND UMD

    Chief among them is recasting the leading role dark matter plays in drawing the universe together, as described by a well-established cosmological model known as Lambda cold dark matter (LCDM).

    Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes
    Alex Mittelmann, Coldcreation

    Simply put, LCDM says that we wouldn’t be here without dark matter. The infant universe was so smooth that the gravitational attraction of ordinary matter alone wouldn’t have been enough to gather particles into galaxies, stars and planets. Enter dark matter particles. LCDM uses their collective bulk to sculpt normal matter into the modern cosmic structures studied by astronomers.

    LCDM became the standard model of cosmology in part because it so precisely agrees with the CMB. This map of the early universe shows almost imperceptibly thick and thin spots rippling through the cosmos. More recently, researchers have been able to measure the orientation or polarization of the CMB’s light more precisely. Any successful cosmology will need to establish a comprehensive history of the cosmos by reproducing these three observations: the CMB’s temperature, the CMB’s polarization, and the current distribution of galaxies and galaxy clusters.

    2
    Lucy Reading-Ikkanda/Quanta Magazine; source: doi: 1303.5076v3

    In the second preprint, Kris Pardo, an astrophysicist at NASA’s Jet Propulsion Laboratory, and David Spergel, director of the Center for Computational Astrophysics at the Flatiron Institute, quantified how difficult it would be for any alternative theory of gravity to compete with one particular feature of LCDM. (Quanta Magazine is an editorially independent publication sponsored by the Simons Foundation, which also funds the Flatiron Institute.) When denser zones of dark matter dragged matter toward them, eventually forming galaxies and stars, this would have largely—but not entirely—washed out the ripples initially moving through the matter. By comparing the CMB’s polarization with today’s patterns of matter, cosmologists can cleanly measure just such an effect: ripple remnants 100 times smaller than the undulations seen in the CMB persist today.

    Re-creating these and other features without LCDM’s titular ingredient, Spergel showed, requires the finest of theoretical needle threading. “We haven’t disproven the existence of all these [modified-gravity theories],” he said. “But any alternative theory has to jump through these hoops.”

    Dark Dust

    Tom Złosnik and Constantinos Skordis, theorists at the Central European Institute for Cosmology and Fundamental Physics, believe they’ve done just that—although in a way that might surprise MOND skeptics and fans alike. They managed to construct a theory of gravity that contains an ingredient that acts exactly like an invisible form of matter on cosmic scales, blurring the line between the dark matter and MOND paradigms.

    Their theory, dubbed RelMOND, adds to the equations of general relativity an omnipresent field that behaves differently in different arenas. On the grandest scales, where the universe noticeably stretches as it expands, the field acts like invisible matter. In this mode, which Złosnik refers to as “dark dust,” the field could have shaped the visible universe just as dark matter would. The model faithfully reproduces the temperature of the CMB—the result that the duo published in their preprint—and Złosnik says it can also match the polarization spectrum and the matter distribution, although they have not yet published these plots.

    “[RelMOND] cannot do worse than LCDM,” said Złosnik, because it very closely mimics that theory for the universe as a whole.

    But if we zoom in on a galaxy, where the fabric of space holds rather still, the field acts in a way that’s true to its MOND roots: It entwines itself with the standard gravitational field, beefing it up just enough to hold a galaxy together without extra matter. (The researchers aren’t yet sure how the field acts for larger clusters of galaxies, a perennial MOND sore spot, and they suggest that this intermediate scale might be a good place to look for observational clues that could set the theory apart.)

    Despite the pair’s mathematical achievement, dark matter remains the simpler theory. Constructing the new field takes four new moving mathematical parts, while LCDM handles dark matter with just one. Hooper likens the situation to a detective debating whether the person at a murder scene is the murderer, or if they were framed by the CIA. Even if the available evidence matches both theories, one requires less of a leap.

    All the same, he doesn’t begrudge others working on what he considers a cosmological conspiracy theory. “I’m glad smart people are thinking about MOND,” he said.

    Złosnik hopes dark matter will be detected soon, but in the meantime, he sees his work on MOND more as an exercise in stretching general relativity to its limits than as a full assault on the cosmological establishment. For now, he’s just pleased to have helped show that the mathematics of gravity may accommodate weirder phenomena than many thought.

    “There’s a danger of missing out on something useful just by assuming that it’s not possible,” Złosnik said. “It might point the way to something a bit more successful.”

    ______________________________________________

    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, 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

    The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

    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 4:30 pm on March 6, 2020 Permalink | Reply
    Tags: , , , , , , Dark Matter Background: Fritz Zwicky and Vera Rubin,   

    From Harvard-Smithsonian Center for Astrophysics: “Dark Matter and Massive Galaxies” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    March 6, 2020

    1
    A dark matter map, created by Japanese astronomers using weak lensing.
    The background image of a wide field of galaxies was analyzed for weak lensing effects and the inferred dark matter distribution is indicated with the contours. Satoshi Miyazaki.

    About eighty-five percent of the matter in the universe is in the form of Dark Matter, whose nature remains a mystery, and the rest is of the kind found in atoms. Dark matter exhibits gravity but otherwise does not interact with normal matter, nor does it emit light. Astronomers studying the evolution of galaxies find that because it is so abundant dark matter does, however, dominate the formation in the universe of large-scale structures like clusters of galaxies.

    Despite being hard to detect directly, dark matter can be traced by modeling sensitive observations of the distributions of galaxies across a range of scales. Galaxies generally reside at the centers of vast clumps of dark matter called haloes because they surround the galaxies. Gravitational lensing of more distant galaxies by foreground dark matter haloes offers a particularly unique and powerful probe of the detailed distribution of dark matter.

    Gravitational Lensing

    Gravitational Lensing NASA/ESA

    “Weak lensing” results in modestly yet systematically deforming shapes of background galaxies and can provide robust constraints on the distribution of dark matter within the clusters; “strong lensing,” in contrast, creates highly distorted, magnified and occasionally multiple images of a single source.

    In the past decade, observations and hydrodynamic simulations have significantly furthered our understanding of how massive galaxies develop, with a two-phase scenario now favored. In the first step, the massive cores of today’s galaxies form at cosmological times from the gravitational collapse of matter into a galaxy, together with their surrounding dark matter halo. Star-formation then boosts the stellar mass of the galaxy. The most massive galaxies, however, have a second phase in which they capture stars from the outer regions of other galaxies, and once their own star formation subsides this phase dominates their assembly. Computer models and some observational results appear to confirm this scenario.

    CfA astronomer Joshua Speagle was a member of a team that used ultra-sensitive, wide-field-of-view imaging at optical and near infrared wavelength on the Subaru telescope to study massive galaxy assembly.


    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

    Their technique took advantage of weak lensing effects because massive galaxies also tend to have more massive, dark matter haloes that distort light. The astronomers studied about 3200 galaxies whose stellar masses are more than that of the Milky Way (roughly about four hundred billion solar masses). Using weak lensing analyses, they found that information about the assembly history of massive dark matter halos is encoded in the stellar mass distributions of massive central galaxies. Among other implications, the scientists show that for galaxies of the same mass, those with more extended shapes tend to have more massive dark matter halos. The results open a new window for exploring how massive galaxies form and evolve over cosmic time.

    Science paper:
    Weak Lensing Reveals a Tight Connection between Dark Matter Halo Mass and the Distribution of Stellar Mass in Massive Galaxies
    MNRAS

    ____________________________________________________

    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, 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

    The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    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 Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
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