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  • richardmitnick 4:30 pm on August 18, 2020 Permalink | Reply
    Tags: , , , , CfA, , ,   

    From Harvard-Smithsonian Center for Astrophysics: “Where Might Very Unequal Mass Black Hole Binaries Come From?” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    1
    A schematic showing two pathways (each one requiring two prior black hole binary merging events) to assemble a roughly 30 solar-mass black like the one detected in a recent black hole binary gravitational wave merger event. Astronomers trying to explain where the massive spinning black hole in the pair was formed conclude that in dense stellar clusters a three-step process is the most likely path. Rodriguez et al., 2020.

    The direct detection of gravitational waves from at least eleven sources during the past five years has offered spectacular confirmation of Einstein’s model of gravity and space-time, while the modeling of these events has provided information on star formation, gamma-ray bursts,neutron stars, the age of the universe, and even verification of ideas about how very heavy elements are produced. The majority of these gravitational wave events arose from the merger of two black holes of comparable masses in an orbiting pair. Near-equal mass pairs are strongly preferred in models of binary black hole formation, whether they result from the evolution of isolated binary stars or from the dynamical pairing of two black holes. This year, however, the LIGO and Virgo gravitational wave observatories reported the first detection of a very unequal mass pair of black holes, GW190412, whose estimated masses are about 30 and 8 solar-masses. The question, then, is how were they formed?

    MIT /Caltech Advanced aLigo

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

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    CfA astronomer Carl Rodriguez led a team of colleagues in a theoretical investigation of how such an unequal mass binary might form. The most obvious solution is look in a dense star cluster, where low-spin, comparable mass black hole pairs can naturally form, in part because massive black holes and stars tend to sink toward the center of the cluster and can more readily encounter each other. But even there those encounters are unlikely to produce an unequal mass pair. The spin of each black hole adds a further complicating factor. The spin is quantified by a number between zero and one. If each of the black holes in a merger has a low value of spin, as is expected, then their merger will normally produce a more massive black hole whose spin is large, perhaps around 0.7, but the inferred spin of the massive black hole in GW190412 is well determined to be about 0.43, suggesting that it did not arise from such a simple merger.

    The astronomers argue that the most likely way to produce this unlikely pair may be through two prior black hole pair mergers in the cluster, a process that can ultimately result in a black hole with the correct inferred spin. First, two black hole binary pairs each merge; each of these pairs has black holes of comparable moderate masses and each produces a more massive black hole. Next, these two new black holes themselves form a binary pair and then merge, producing the roughly 30 solar-mass, moderate spin black hole as seen. Then that blackhole pairs up with a low mass black hole to form the binary whose collapse produced the event seen as GW190412. (Similar multi-step variants are possible as well.) Although such a series of events are rare, the scientists show that known star clusters could provide the right environments for it to occur. The new result and analysis, as in the case of previous gravitational wave discoveries, have expanded our view of cosmic variety while tacking fundamental assumptions. One of those assumptions is that black holes are typically formed from stellar collapse with low spins. Future work will show whether a three-step merger process is needed to explain events like GW190412, or whether assumptions like this one about spin need to be challenged instead.

    Science paper:
    GW190412 as a Third-generation Black Hole Merger from a Super Star Cluster
    The Astrophysical Journal Letters

    See the full article here .


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    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.

     
  • richardmitnick 12:55 pm on July 27, 2020 Permalink | Reply
    Tags: , , , , CfA, ,   

    From Harvard-Smithsonian Center for Astrophysics and NJIT: “CfA Scientists and Team Take a Look Inside the Central Engine of a Solar Flare for the First Time” 

    Harvard Smithsonian Center for Astrophysics

    From Harvard-Smithsonian Center for Astrophysics and NJIT

    July 27, 2020

    Amy Oliver
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    Fred Lawrence Whipple Observatory
    520-879-4406
    amy.oliver@cfa.harvard.edu

    1
    Observation of a large solar flare on Sept. 10, 2017 in extreme ultraviolet (grayscale background, by NASA’s Solar Dynamics Observatory) and microwaves (red to blue indicate increasing frequencies, observed by the Expanded Owens Valley Solar Array). Light orange curves are selected magnetic field lines from the matching theoretical solar eruptive flare model. The flare is driven by the eruption of a twisted magnetic flux rope (illustrated by a bundle of color curves threading the dark cavity). Microwave sources are observed throughout the region below the cavity where a large-scale reconnection current sheet — the flare’s “central engine” — is located, providing crucial measurements for its physical
    properties.Credit: NJIT-CSTR, B. Chen, S. Yu; NASA Solar Dynamics Observatory

    NASA SDO

    Scientists from the Center for Astrophysics | Harvard & Smithsonian and the New Jersey Institute of Technology today announced the first successful measurement and characterization of the “central engine” of large solar flare. The findings, published today in Nature Astronomy, reveal the source of the intense energy powering solar flares.

    According to the study—which closely examined a large solar flare accompanied by a powerful eruption captured on September 10, 2017, by the NJI’s Owens Valley Solar Array (EOVSA), at microwaves—the intense energy powering the flare is the result of an enormous electric current “sheet” stretching more than 40,000 kilometers—greater than the length of three Earths placed side-by-side—through the core flaring region, where opposing magnetic field lines approach, break, and reconnect.

    15 radio telescopes of NJIT Owens Valley Solar Array, near Big Pine, California, USA, Altitude 1,200 m (3,900 ft)

    “During large eruptions on the Sun, particles such as electrons can get accelerated to high energies,” said Kathy Reeves, astrophysicist, CfA, and co-author on the study. “How exactly this happens is not clearly understood, but it is thought to be related to the Sun’s magnetic field.” Bin Chen, professor of physics at NJIT and lead author on the study added, “It has long been suggested that the sudden release of magnetic energy through the reconnection current sheet is responsible for these major eruptions, yet there has been no measurement of its magnetic properties. With this study, we’ve finally measured the details of the magnetic field of a current sheet for the first time, giving us a new understanding of the central engine of the Sun’s solar flares.”

    Measurements taken during the study also indicate a magnetic, bottle-like structure located at the top of the flare’s loop-shaped base, or flare arcade, at a height of nearly 20,000 kilometers above the surface of the Sun. The study suggests that this is the primary site where a solar flare’s highly energetic electrons are trapped and accelerated to nearly the speed of light.

    “We found that there were a lot of accelerated particles just above the bright, flaring loops,” said Reeves. “The microwaves, coupled with modeling, tells us there is a minimum in the magnetic field at the location where we see the most accelerated particles, and a strong magnetic field in the linear, sheet-like structure further above the loops.”

    The sheet-like structure and the loops seem to be working in concert, with significant magnetic energy being pumped into the current sheet at an estimated rate of 10-100 billion trillion joules per second, and 99% of the flare’s relativistic electrons were observed congregating at the magnetic bottle. “While the current sheet seems to be the place where the energy is released to get the ball rolling, most of the electron acceleration appears to be occurring in this other location, the magnetic bottle,” said Dale Gary, director, EOVSA and co-author on the study. “Others have proposed such a structure in solar flares before, but we can truly see it now in the numbers.” Chen added, “What our data showed was a special location at the bottom of the current sheet—the magnetic bottle—appears to be crucial in producing or confining the relativistic electrons.”

    The study results were achieved through a combination of microwave observations from EOVSA and extreme ultra-violet imaging observations from the Smithsonian Astrophysical Observatory’s Atmospheric Imaging Assembly on the Solar Dynamics Observatory (SDO). The observations were combined with analytical and numerical modeling—based on a 1990s theoretical model of solar flare physics—to help scientists understand the structure of the magnetic field during a large solar eruption.

    “Our model was used for computing the physics of the magnetic forces during this eruption, which manifests as a highly twisted ‘rope’ of magnetic field lines, or magnetic flux rope,” said Reeves. “It is remarkable that this complicated process can be captured by a straightforward analytical model, and that the predicted and measured magnetic fields match so well.”

    Performed by Chengcai Shen, astrophysicist, CfA, the simulations allowed the team to resolve the thin reconnection current sheet and capture it in detail. “Our simulation results match both the theoretical prediction on magnetic field configuration during a solar eruption and reproduce a set of observable features from this particular flare, including magnetic strength and plasma inflow/outflows around the reconnecting current sheet,” said Shen. “It is a powerful tool to compare theoretical expectations and observations in detail.”

    For the team, the study provides answers to long-unanswered questions about the Sun and its solar flares. “The place where all the energy is stored and released in solar flares has been invisible until now,” said Gary. “To play on a term from cosmology, it is the Sun’s ‘dark energy problem,’ and previously we’ve had to infer indirectly that the flare’s magnetic reconnection sheet existed.” For solar physics, the measurements represent a better understanding of the Sun, as well as providing a path to revealing the truth behind the current sheet, and the magnetic bottle and its role in particle acceleration. According to Chen, “There are certainly huge prospects out there for us to study that address these fundamental questions.”

    The current study builds on the team’s quantitative measurements of the evolving magnetic field strength directly follow a solar flare’s ignition, published in Science earlier this year.

    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.

     
  • richardmitnick 3:22 pm on July 9, 2020 Permalink | Reply
    Tags: "Harvard Scientists Propose Plan to Determine If Planet Nine Is a Primordial Black Hole", , , , CfA,   

    From Harvard-Smithsonian Center for Astrophysics: “Harvard Scientists Propose Plan to Determine If Planet Nine Is a Primordial Black Hole” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    July 9, 2020
    Amy Oliver
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    Fred Lawrence Whipple Observatory
    520-879-4406
    amy.oliver@cfa.harvard.edu

    1

    Scientists at Harvard University and the Black Hole Initiative (BHI) have developed a new method to find black holes in the outer solar system, and along with it, determine once-and-for-all the true nature of the hypothesized Planet Nine. The paper, accepted to The Astrophysical Journal Letters, highlights the ability of the future Legacy Survey of Space and Time (LSST) mission to observe accretion flares, the presence of which could prove or rule out Planet Nine as a black hole.

    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.

    Dr. Avi Loeb, Frank B. Baird Jr. Professor of Science at Harvard, and Amir Siraj, a Harvard undergraduate student, have developed the new method to search for black holes in the outer solar system, based on flares that result from the disruption of intercepted comets. The study suggests that the LSST has the capability to find black holes by observing for accretion flares resulting from the impact of small Oort cloud objects.

    “In the vicinity of a black hole, small bodies that approach it will melt as a result of heating from the background accretion of gas from the interstellar medium onto the black hole,” said Siraj. “Once they melt, the small bodies are subject to tidal disruption by the black hole, followed by accretion from the tidally disrupted body onto the black hole.” Loeb added, “Because black holes are intrinsically dark, the radiation that matter emits on its way to the mouth of the black hole is our only way to illuminate this dark environment.”

    Future searches for primordial black holes could be informed by the new calculation. “This method can detect or rule out trapped planet-mass black holes out to the edge of the Oort cloud, or about a hundred thousand astronomical units,” said Siraj. “It could be capable of placing new limits on the fraction of dark matter contained in primordial black holes.”

    The upcoming LSST is expected to have the sensitivity required to detect accretion flares, while current technology isn’t able to do so without guidance. “LSST has a wide field of view, covering the entire sky again and again, and searching for transient flares,” said Loeb. “Other telescopes are good at pointing at a known target but we do not know exactly where to look for Planet Nine. We only know the broad region in which it may reside.” Siraj added, “LSST’s ability to survey the sky twice per week is extremely valuable. In addition, its unprecedented depth will allow for the detection of flares resulting from relatively small impactors, which are more frequent than large ones.”

    The new paper focuses on the famed Planet Nine as a prime first candidate for detection. The subject of much speculation, most theories suggest that Planet Nine is a previously undetected planet, but it may also flag the existence of a planet-mass black hole.

    “Planet Nine is a compelling explanation for the observed clustering of some objects beyond the orbit of Neptune. If the existence of Planet Nine is confirmed through a direct electromagnetic search, it will be the first detection of a new planet in the solar system in two centuries, not counting Pluto, said Siraj, adding that a failure to detect light from Planet Nine—or other recent models, such as the suggestion to send probes to measure gravitational influence—would make the black hole model intriguing. “There has been a great deal of speculation concerning alternative explanations for the anomalous orbits observed in the outer solar system. One of the ideas put forth was the possibility that Planet Nine could be a grapefruit-sized black hole with a mass of five to ten times that of the Earth.”

    The focus on Planet Nine is based both in the unprecedented scientific significance that a hypothetical discovery of a planet-mass black hole in the solar system would hold as well as the continued interest in understanding what’s out there. “The outskirts of the solar system is our backyard. Finding Planet Nine is like discovering a cousin living in the shed behind your home which you never knew about,” said Loeb. “It immediately raises questions: why is it there? How did it obtain its properties? Did it shape the solar system history? Are there more like it?”

    The research was funded in part by a grant from the Breakthrough Prize Foundation, and by Harvard’s Black Hole Initiative (BHI), which is funded by grants from the John Templeton Foundation (JTF) and the Gordon and Betty Moore Foundation (GBMF)

    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.

     
  • richardmitnick 10:53 am on July 3, 2020 Permalink | Reply
    Tags: "Measuring the Structure of a Giant Solar Flare", CfA,   

    From Harvard-Smithsonian Center for Astrophysics: “Measuring the Structure of a Giant Solar Flare” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    1
    An ultraviolet image of a giant solar flare on 2017-09-10 as seen by SDO, the Solar Dynamics Observatory.

    NASA SDO

    White contours show the magnetic field lines derived from models; the red regions show the high resolution microwave images from the Expanded Owens Valley Solar Array (EOVSA) that reveal the fast-rising, balloon-shaped, erupting hot gas (the scale shows the frequency of the observations).

    15 radio telescopes of NJIT Owens Valley Solar Array, near Big Pine, California, USA, Altitude 1,200 m (3,900 ft)


    These high spatial resolution images have enabled astronomers top confirm that these regions are the primary locations for accelerating and channeling the fast-moving electrons into interplanetary space. Credit:NSF, NASA, and Chen et al. 2020

    The sun’s corona, its hot outermost layer, has a temperature of over a million degrees Kelvin, and produces a wind of charged particles, about one-millionth of the moon’s mass is ejected each year. Transient events have been known to cause large eruptions of high-energy charged particles into space, some of which bombard the Earth, producing auroral glows and occasionally veven disrupting global communications. One issue that has long puzzled astronomers is how the sun produces these high-energy particles.

    Flares or other kinds of impulsive events are thought to be key mechanisms. The hot gas is ionized and produces an underlying sheet of circulating current that generates powerful magnetic field loops. When these loops twist and break they can abruptly eject pulses of charged particles. In the standard picture of solar flares, large-scale motions drive this activity, but where and how the energy is released locally, and how the particles are accelerated, have remained uncertain because the magnetic properties of the large-scale current sheet have not been measured at sizes small enough to correspond to the domains of flaring activity.

    CfA astronomers Chengcai Shen, Katharine Reeves and a team of their collaborators report spatially resolved observations of the regions of magnetic field and flare-ejected electron activity. The team used the thirteen antenna array at the Expanded Owens Valley Solar Array (EOVSA) and its microwave imaging techniques to observe the giant solar flare on 2017 September 10. As the event progressed they saw a rapidly ascending, balloon-shaped dark cavity, corresponding to twisted magnetic field lines rising, breaking, and ejecting electrons as viewed roughly along the axis of the field lines. The scientists were able to model the details of the configuration, and by estimating the strength of the magnetic field and the speed of the plasma flow, they determined that this one large flare alone released during its peak few minutes about .02% of the energy of the entire sun. Their results suggest that these kinds of spatial structures in the field are the primary locations for accelerating and channeling the fast-moving electrons into interplanetary space, and demonstrate the power of these new, spatially resolved imaging techniques.

    Science paper:
    “Measurement of Magnetic Field and Relativistic Electrons Along a Solar Flare Current Sheet”
    Nature Astronomy

    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.

     
  • richardmitnick 2:43 pm on June 22, 2020 Permalink | Reply
    Tags: CfA, CfA Scientists Collaborate on New Study to Search the Universe for Signs of Technological Civilizations", Exoplanet LHS 1140b, ,   

    From Harvard-Smithsonian Center for Astrophysics and University of Rochester: “CfA Scientists Collaborate on New Study to Search the Universe for Signs of Technological Civilizations” 

    University of Rochester

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    June 19, 2020

    Amy Oliver
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    Fred Lawrence Whipple Observatory
    520-879-4406
    amy.oliver@cfa.harvard.edu

    1
    Artist’s impression of the exoplanet LHS 1140b, which orbits its star within the “habitable zone” where liquid water might exist on the surface. The LHS 1140 system is only about 40 light-years from Earth, making it a possible target for studying the atmosphere of the planet if it has one. Credit: M. Weiss/CfA

    Scientists at the Center for Astrophysics | Harvard & Smithsonian and the University of Rochester are collaborating on a project to search the universe for signs of life via technosignatures, after receiving the first NASA non-radio technosignatures grant ever awarded, and the first SETI-specific NASA grant in over three decades.

    Researchers believe that although life appears in many forms, the scientific principles remain the same, and that the technosignatures identifiable on Earth will also be identifiable in some fashion outside of the solar system. “Technosignatures relate to signatures of advanced alien technologies similar to, or perhaps more sophisticated than, what we possess,” said Avi Loeb, Frank B. Baird Jr. Professor of Science at Harvard. “Such signatures might include industrial pollution of atmospheres, city lights, photovoltaic cells (solar panels), megastructures, or swarms of satellites.”

    Knowing where to look for technosignatures hasn’t always been easy, making it difficult for researchers to obtain grants and a footing in mainstream astronomy. The surge of results in exoplanetary research—including planets in habitable zones and the presence of atmospheric water vapor—over the past five years has revitalized the search for intelligent life. “The Search for Extraterrestrial Intelligence (SETI) has always faced the challenge of figuring out where to look. Which stars do you point your telescope at and look for signals?” said Adam Frank, a professor of physics and astronomy at the University of Rochester, and the primary recipient of the grant. “Now we know where to look. We have thousands of exoplanets including planets in the habitable zone where life can form. The game has changed.”

    The study, “Characterizing Atmospheric Technosignatures,” will initially focus on searching for two particular signatures that may indicate the presence of technological activities on extrasolar planetary bodies: solar panels and pollutants.

    Solar panels are rapidly gaining in popularity as a means for harnessing the energy of Earth’s sun, and researchers believe other civilizations will do the same with their own stars as they seek new means to produce energy. “The nearest star to Earth, Proxima Centauri, hosts a habitable planet, Proxima b.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    The planet is thought to be tidally locked with permanent day and night sides,” said Loeb. “If a civilization wants to illuminate or warm up the night side, they would place photovoltaic cells on the day side and transfer the electric power gained to the night side.” Frank added, “Our job is to say, ‘this wavelength band’ is where you would see sunlight reflected off solar panels. This way astronomers observing a distant exoplanet will know where and what to look for if they’re searching for technosignatures.”

    In the search for life outside of the solar system, scientists also often turn to biosignatures detected as chemicals in planetary atmospheres. Jason Wright, Penn State University, said, “We have come a long way toward understanding how we might detect life on other worlds from the gases present in those worlds’ atmospheres.” While scientists can search for those chemicals produced naturally by life, like methane, they are now also searching for artificial chemicals and gases. “We pollute Earth’s atmosphere with our industrial activity,” said Loeb. “If another civilization had been doing it for much longer than we have, then their planet’s atmosphere might show detectable signs of artificially produced molecules that nature is very unlikely to produce spontaneously, such as chlorofluorocarbons (CFCs).” The presence of CFCs—or refrigerant—therefore, could indicate the presence of industrial activity.

    Loeb, Frank, and Wright are joined by Mansavi Lingam of the Florida Institute of Technology, and Jacob Haqq-Misra of Blue Marble Space. The study aims to eventually produce the first entries for an online technosignatures library.

    “My hope is that, using this grant, we will quantify new ways to probe signs of alien technological civilizations that are similar to or much more advanced than our own,” said Loeb. “The fundamental question we are trying to address is: are we alone? But I would add to that: even if we are alone right now, were we alone in the past?”

    About Center for Astrophysics | Harvard & Smithsonian

    Headquartered in Cambridge, Mass., the Center for Astrophysics | Harvard & Smithsonian (CfA) is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

    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.

    U Rochester

    The University of Rochester is one of the country’s top-tier research universities. Our 158 buildings house more than 200 academic majors, more than 2,000 faculty and instructional staff, and some 10,500 students—approximately half of whom are women.

    Learning at the University of Rochester is also on a very personal scale. Rochester remains one of the smallest and most collegiate among top research universities, with smaller classes, a low 10:1 student to teacher ratio, and increased interactions with faculty.

     
  • richardmitnick 11:41 am on June 5, 2020 Permalink | Reply
    Tags: CfA   

    From Harvard-Smithsonian Center for Astrophysics: “A New Catalog of Infrared Dark Clouds” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    June 5, 2020

    1
    A false-color infrared image of the Infrared Dark Cloud called “the Snake” as seen by the IRAC camera on the Spitzer Space Telescope. Astronomers have produced a new catalog of IRDCs from IRAC’s sky survey images using a new computational search-and-detection algorithm. (Blue dots are stars relatively undimmed by dust, while the red dots are young stars embedded in the cloud.)

    NASA, JPL-Caltech/S. Carey (SSC/Caltech)

    NASA/Spitzer Infrared Telescope. No longer in service.

    Infrared dark clouds (IRDCs) are dark patches of cold dust and gas seen in the sky against the bright diffuse infrared glow of warm dust in our galaxy. These IRDCs, massive and rich in molecules, are natural sites for star birth – one of the main reasons why astronomers are actively studying them. IRDCs were first detected by two early space infrared missions, the Infrared Space Observatory and the Midcourse Space Experiment, but the IRAC camera on Spitzer revolutionized the field with its dramatically enhanced sensitivity and spatial resolution. IRAC had completed several surveys of the Milky Way before being shut off last February, and astronomers have been using the infrared images to identify and analyze the characteristics of IRDCs. The Submillimeter Array and ALMA facilities, operating with high sensitivity and resolution at submillimeter wavelengths where the cold molecular gas can be characterized, have enabled astronomers to follow up on these newly discovered sources and to determine the gas temperatures, densities and motions, leading to advances in our understanding of the earliest stages of star formation in these stellar nurseries.

    CfA Submillimeter Array Mauna Kea, Hawaii, USA, Altitude 4,080 m (13,390 ft)

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    One issue constraining research has been the lack of an up-to-date catalog of IRDCs. There are three main difficulties: IRDC sizes can vary greatly, from those that are very extended (more than a light-year in size) to others that are over one hundred times smaller (and of course their distances are key to their angular appearances), their shapes are usually irregular and ill defined, and not least they often are located in complex regions with hundreds of other sources. Searching the Milky Way for them has been a daunting task.

    CfA astronomers Jyothish Pariu and Joe Hora have just completed a new catalog of IRDCs containing 18,845 objects extracted from the IRAC infrared images using a new computer algorithm they developed that uses contour finding and so-called neural network methods. The technique scans the images for the clouds’ dark edges and closed contours, and evaluates the reliability of the detections in an automated, objective technique that could be extended to use with other surveys. The results of the new catalog are in good agreement with earlier findings, but in addition to finding many more objects the new catalog contains more IRDCs in low-contrast regions and also confirms (as expected) that many of the previously identified IRDCs are actually comprised of two or more smaller objects.

    Science paper:
    “A Semi-automated Computational Approach for Infrared Dark Cloud Localization: A Catalog of Infrared Dark Clouds”
    Publications of the Astronomical Society of the Pacific

    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.

     
  • richardmitnick 12:15 pm on June 2, 2020 Permalink | Reply
    Tags: "Scientists Detect Crab Nebula Using Innovative Gamma-Ray Telescope Proving Technology Viability", CfA, Laying the groundwork for the future of gamma-ray astrophysics., , The use of secondary mirrors in gamma-ray telescopes is a leap forward in innovation for the relatively young field of very-high-energy gamma-ray astronomy.,   

    From Harvard-Smithsonian Center for Astrophysics: “Scientists Detect Crab Nebula Using Innovative Gamma-Ray Telescope, Proving Technology Viability” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    June 1, 2020

    Project contacts:

    Center for Astrophysics | Harvard & Smithsonian
    Wystan Benbow
    617-496-7597
    wbenbow@cfa.harvard.edu

    University of Wisconsin
    Justin Vandenbroucke
    608-890-1477
    justin.vandenbroucke@wisc.edu

    University of California, Los Angeles
    Vladimir Vassiliev
    310-267-5878
    vvv@astro.ucla.edu

    Media contact:

    Amy Oliver
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    Fred Lawrence Whipple Observatory
    801-783-9067
    amy.oliver@cfa.harvard.edu

    1
    Prototype Schwarzschild-Couder Telescope (pSCT), located at the Fred Lawrence Whipple Observatory in Amado, Arizona

    Čerenkov Telescope Array, http://www.isdc.unige.ch/cta/ at Cerro Paranal, located in the Atacama Desert of northern Chile searches for cosmic rays on Cerro Paranal at 2,635 m (8,645 ft) altitude, 120 km (70 mi) south of Antofagasta; and at at the Instituto de Astrofisica de Canarias (IAC), Roque de los Muchachos Observatory in La Palma, Spain

    Scientists in the Čerenkov Telescope Array (CTA) consortium today announced at the 236th meeting of the American Astronomical Society (AAS) that they have detected gamma rays from the Crab Nebula using a prototype Schwarzschild-Couder Telescope (pSCT), proving the viability of the novel telescope design for use in gamma-ray astrophysics.

    “The Crab Nebula is the brightest steady source of TeV, or very-high-energy, gamma rays in the sky, so detecting it is an excellent way of proving the pSCT technology,” said Justin Vandenbroucke, Associate Professor, University of Wisconsin. “Very-high-energy gamma rays are the highest energy photons in the universe and can unveil the physics of extreme objects including black holes and possibly dark matter.”

    Detecting the Crab Nebula with the pSCT is more than just proof-positive for the telescope itself. It lays the groundwork for the future of gamma-ray astrophysics. “We’ve established this new technology, which will measure gamma rays with extraordinary precision, enabling future discoveries,” said Vandenbroucke. “Gamma-ray astronomy is already at the heart of the new multi-messenger astrophysics, and the SCT technology will make it an even more important player.”

    The use of secondary mirrors in gamma-ray telescopes is a leap forward in innovation for the relatively young field of very-high-energy gamma-ray astronomy, which has moved rapidly to the forefront of astrophysics. “Just over three decades ago, TeV gamma rays were first detected in the universe, from the Crab Nebula, on the same mountain where the pSCT sits today,” said Vandenbroucke. “That was a real breakthrough, opening a cosmic window with light that is a trillion times more energetic than we can see with our eyes. Today, we’re using two mirror surfaces instead of one, and state-of-the-art sensors and electronics to study these gamma rays with exquisite resolution.”

    The initial pSCT Crab Nebula detection was made possible by leveraging key simultaneous observations with the co-located VERITAS (Very Energetic Radiation Imaging Telescope Array System) observatory.

    CfA/VERITAS, a major ground-based gamma-ray observatory with an array of four 12m Čerenkov Telescopes for gamma-ray astronomy in the GeV – TeV energy range. Located at Fred Lawrence Whipple Observatory,Mount Hopkins, Arizona, US in AZ, USA, Altitude 2,606 m (8,550 ft)

    “We have successfully evolved the way gamma-ray astronomy has been done during the past 50 years, enabling studies to be performed in much less time,” said Wystan Benbow, Director, VERITAS. “Several future programs will particularly benefit, including surveys of the gamma-ray sky, studies of large objects like supernova remnants, and searches for multi-messenger counterparts to astrophysical neutrinos and gravitational wave events.”

    Located at the Fred Lawrence Whipple Observatory in Amado, Arizona—the largest field site of the Center for Astrophysics | Harvard & Smithsonian—the pSCT was inaugurated in January 2019 and saw first light the same week. After a year of commissioning work, scientists began observing the Crab Nebula in January 2020, but the project has been underway for more than a decade.

    “We first proposed the idea of applying this optical system to TeV gamma-ray astronomy nearly 15 years ago, and my colleagues and I built a team in the US and internationally to prove that this technology could work,” said Prof. Vladimir Vassiliev, Principal Investigator, pSCT. “What was once a theoretical limit to this technology is now well within our grasp, and continued improvements to the technology and the electronics will further increase our capability to detect gamma rays at resolutions and rates we once only ever dreamed of.”

    The pSCT was made possible by the contributions of thirty institutions and five critical industry partners across the United States, Italy, Germany, Japan, and Mexico, and by funding through the U.S National Science Foundation Major Research Instrumentation Program.

    “That a prototype of a future facility can yield such a tantalizing result promises great things from the full capability, and exemplifies NSF’s interest in creating new possibilities that can enable a project to attract wide-spread support,” said Nigel Sharp, Program Manager, National Science Foundation.

    Now demonstrated, the pSCT’s current and upcoming innovations will lay the groundwork for use in the future Čerenkov Telescope Array observatory, which will host more than 100 gamma-ray telescopes. “The pSCT, and its innovations, are pathfinding for the future CTA, which will detect gamma-ray sources at around 100 times faster than VERITAS, which is the current state of the art,” said Benbow. “We have demonstrated that this new technology for gamma-ray astronomy unequivocally works. The promise is there for this groundbreaking new observatory, and it opens a tremendous amount of discovery potential.”

    About the pSCT

    The SCT optical design was first conceptualized by U.S. members of CTA in 2006, and the construction of the pSCT was funded in 2012. Preparation of the pSCT site at the base of Mt. Hopkins in Amado, AZ, began in late 2014, and the steel structure was assembled on site in 2016. The installation of the pSCT’s 9.7-m primary mirror surface —consisting of 48 aspheric mirror panels—occurred in early 2018, and was followed by the camera installation in May 2018 and the 5.4-m secondary mirror surface installation—consisting of 24 aspheric mirror panels—in August 2018. Scientists opened the telescope’s optical surfaces and observed first light in January 2019. It began scientific operations in January 2020. The SCT is based on a 114 year-old two-mirror optical system first proposed by Karl Schwarzschild in 1905, but only recently became possible to construct due to the essential research and development progress made at the Brera Astronomical Observatory, the Media Lario Technologies Incorporated and the Istituto Nazionale di Fisica Nucleare, all located in Italy. pSCT operations are funded by the National Science Foundation and the Smithsonian Institution.

    For more information visit https://www.cta-observatory.org/project/technology/sct/

    About CTA

    CTA is a global initiative to build the world’s largest and most sensitive very-high-energy gamma-ray observatory consisting of about 120 telescopes split into a southern array at Paranal, Chile and a northern array at La Palma, Spain. More than 1,500 scientists and engineers from 31 countries are engaged in the scientific and technical development of CTA. Plans for the construction of the observatory are managed by the CTAO gGmbH, which is governed by Shareholders and Associate Members from a growing number of countries. CTA will be the first ground-based gamma-ray astronomy observatory open to the worldwide astronomical and particle physics communities.

    For more information visit http://cta-observatory.org/

    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.

     
  • richardmitnick 11:50 am on June 2, 2020 Permalink | Reply
    Tags: "Galactic Star Formation and Supermassive Black Hole Masses", , , , CfA, ,   

    From Harvard-Smithsonian Center for Astrophysics: “Galactic Star Formation and Supermassive Black Hole Masses” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    May 29, 2020

    1
    A simulation of the stellar content of the universe today seen across one hundred million light-years. Astronomers used this simulation to investigate how accretion onto a supermassive black hole quenches galaxy star formation. Credit: The IllustrisTNG Project

    Astronomers studying how star formation evolved over cosmic time have discovered that quiescent galaxies (galaxies that are currently not making many new stars) frequently have active galactic nuclei. These AGN accrete material onto hot circumnuclear disks, and the resultant energy is released in bursts of radiation, or as jets of particles moving at close to the speed of light. The suspicion is that these outbursts drive gas outflows over thousands of light-years, disrupting and dispersing potential star forming material in a process called quenching. The quenching mechanism is in addition a self-limiting one since the dispersion ultimately suppresses the gas accretion onto the black hole itself. There are other proposed mechanisms for quenching however: supernovae produced during star formation could be responsible (or at least an important contributor) as could strong stellar winds. Verifying these various alternatives is hence a key goal of galactic research.

    CfA astronomers Bryan Terrazas, Rainer Weinberger and Lars Hernquist and their colleagues used the large-scale hydrodynamic simulation called IllustrisTNG to trace the development of galaxies and their black holes, in particular to investigate the correlations between black hole feedback and the suppression of star formation. Although the details of black hole accretion are still only sketchily understood, the simulation allows scientists to vary many input parameters of the simulation to test a range of alternatives.

    The astronomers find that galaxies in the local universe with more than about ten billion masses of stars will indeed tend to quench star production once the energy in the winds from black hole accretion becomes larger than the gravitational energy in the gas, and that this tends to happen when the mass of the supermassive black hole exceeds about one hundred and sixty million solar masses. This value appears to be quite sharply delineated: 90% of galaxies with smaller black holes are actively star forming and 90% of galaxies with larger black holes are quiescent. The team then compared the results of the simulations to observations of ninety one galaxies (although not a completely representative sample of objects) and finds generally good agreement; however, the observations show a much larger range of behavior.

    Science paper:
    “The Relationship between Black Hole Mass and Galaxy Properties: Examining the Black Hole Beedback Model in IllustrisTNG”
    MNRAS

    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.

     
  • richardmitnick 11:28 am on May 25, 2020 Permalink | Reply
    Tags: "Ultraviolet Emitting Galaxies in the Early Universe", , , , CfA, , Lyman alpha emitters ("LAEs")   

    From Harvard-Smithsonian Center for Astrophysics: “Ultraviolet Emitting Galaxies in the Early Universe” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    May 22, 2020

    1
    An multiwavength image of a Lyman alpha galaxy. Astronomers have studied 3700 such galaxies in the early universe to determine how much of the hydrogen emission is produced by star formation and how much by an accreting black hole. In this image yellow is the hydrogen gas glowing in Lyman-alpha; white shows the main galaxy; red is infrared as seen with the IRAC camera; and blue is X-ray emission showing evidence for a supermassive black hole.

    X-ray (NASA/CXC/Durham Univ./D.Alexander et al.); Optical (NASA/ESA/STScI/IoA/S.Chapman et al.); Lyman-alpha Optical (NAOJ/Subaru/Tohoku Univ./T.Hayashino et al.); Infrared (NASA/JPL-Caltech/Durham Univ./J.Geach et al.)

    NASA/Chandra X-ray Telescope

    NASA/ESA Hubble Telescope

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

    NASA Infrared Telescope facility Mauna Kea, Hawaii, USA, 4,207 m (13,802 ft) above sea level

    Massive galaxies in the local universe, in order to be large today, probably began forming their stars in the early universe. Astronomers do indeed see significantly enhanced star-formation activity in distant galaxies and find that the peak star formation rate occurred when the universe was only about two billion years old. Galaxies actively making stars naturally produce many that are massive and hot. They emit ultraviolet radiation that ionizes hydrogen gas which in turn radiates in characteristic spectral lines; the most energetic of these hydrogen features, the Lyman alpha line, itself lies in the ultraviolet. Since galaxies are expanding away from us, however, their apparent spectrum is shifted to the red and their Lyman alpha line is shifted to visible wavelengths or longer, where optical instruments can detect it.

    Lyman alpha emitters (“LAEs”) are galaxies or clusters of galaxies that are bright in this hydrogen feature, and astronomers piecing together the star formation history of the universe use LAEs to trace the cosmic evolution of matter. There is one major complicating factor however: supermassive black holes at galaxy centers accrete matter (AGN: active galactic nuclei) and also produce copious amounts of ultraviolet radiation and hence Lyman alpha light. An accurate accounting of star formation using ultraviolet light has to account for the effects of black hole accretion.

    CfA astronomer Andra Stroe was a member of a team that examined the X-ray and radio activity of about 3700 LAEs to search for and quantify their AGN contributions to the radiation using the distinctive character of accretion radiation at these wavelengths. Their set of objects dates from the epochs between one and two billion years after the big bang, and was selected from deep optical and near infrared images, Chandra X-ray observations, and radio data from a Very Large Array survey.

    NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    They found that 6.8% of the LAEs were also detected in X-rays and hence could be classified as AGN, and that the luminosity of the X-rays correlated with the Lyman alpha strength in these objects suggesting that the hydrogen emission was AGN produced. Summing together the X-ray images of all the other LAEs objects still did not reveal any X-ray emission, implying at most a very low accretion rate in these objects. An even smaller percentage of LAEs, only 3.1% , showed radio emission and there was no correlation between the radio and Lyman alpha fluxes, although this might be due in part to detection limits. Overall, the scientists conclude that LAEs at cosmological distances are mostly star forming (with relatively modest rates, on average about seven solar-masses per year of new stars) and with relatively low AGN accretion except for small subset of X-ray bright objects. The results are a large statistical smaple that support and refine the standard model of galaxy evolution and the character of LAE galaxies in the early universe.

    The X-ray and Radio Activity of Typical and Luminous Ly α Emitters from z ∼ 2 to z ∼ 6: Evidence for a Diverse, Evolving Population,
    MNRAS

    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.

     
  • richardmitnick 1:04 pm on May 15, 2020 Permalink | Reply
    Tags: , , , CfA, , The hot Neptune K2-25, The MEarth-South array of eight 40 cm telescopes with cameras sensitive to optical and near-infrared light.   

    From Harvard-Smithsonian Center for Astrophysics: “An Eccentric Hot Neptune” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    Of the roughly 4300 exoplanets confirmed to date, about ten percent of them are classified as “hot Jupiters.” These are planets with masses between about 0.4 and 12 Jupiter-masses and orbital periods less than about 110 days (implying that they orbit close to their star – usually much closer than Mercury is to the Sun – and have hot surface temperatures). A “hot Neptune” has a smaller mass, closer to that of Neptune which is about twenty times less than Jupiter, and which also orbits close to its star. Astronomers study not only the properties of exoplanets but also how they evolved within their planetary systems. Hot Jupiters and hot Neptunes are puzzles. They are expected to have formed much farther out in the cold reaches of their systems as did the giant planets in our Solar System and then to have migrated inward to their current, close locations. Evidence supporting this evolutionary history should be found in the planets’ orbital eccentricities and other clues, but is difficult to obtain.

    CfA astronomers Jonathan Irwin, David Charbonneau and Jennifer Winters were members of a team that probed the evolution of the hot Neptune K2-25, a transiting exoplanet with an orbital period of only 3.48 days, an estimated mass of roughly about seven Earth-masses, and a highly eccentric orbit (value of 0.27; its maximum distance from the star exceeds its minimum distance by about 70%). K2-25 has the advantage of being in a young stellar cluster whose age is well-constrained at about 650 million years. This young age tests whether there is time for the migration mechanism to work, whether or not such a process could leave the planet with its large observed eccentricity, and not least, whether such a young host star might be active enough to have complicated the dataset with starspots (the star itself is seen to rotate in 1.88 days).

    The team analyzed twenty-two non-consecutive transits of the planet obtained from the MEarth ground-based observatories, the IRAC/Spitzer mission camera, and the Kepler mission, modeling each of the transits separately before merging the conclusions.

    1
    The MEarth-South array of eight 40 cm telescopes with cameras sensitive to optical and near-infrared light. Observations of the hot Neptune, K2-25, with MEarth, IRAC/Spitzer, and Kepler were used to try to confirm whether or not this exoplanet migrated in to its present location after being born in the cold, outer regions of the system. Credit: MEarth Project

    They estimate that the timeframe for an orbit to become circular after migration is about 410 million years, roughly the age of the system, and thus the fact that the orbit is eccentric suggests some other body may be perturbing it. The scientists searched for evidence of other planets in the system that could be responsible by looking for variations in the K2-25’s transit lightcurves, slight differences that would result from their gravitational presence (“transit timing variations”). They found none. The result, although it leaves room for ambiguity, is consistent with the theory that this hot Neptune migrated inward.

    Science paper:
    “The Young Planetary System K2-25: Constraints on Companions and Starspots,”
    The Astronomical Journal

    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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