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  • richardmitnick 8:11 am on January 8, 2020 Permalink | Reply
    Tags: "Early Galaxies", , , , CfA,   

    From Harvard-Smithsonian Center for Astrophysics: “Early Galaxies” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    January 3, 2020

    Galaxies that are very luminous in the infrared are generally active in making new stars whose ultraviolet radiation heats the dust. The energy, re-radiated by the dust at infrared wavelengths, is characterized by having a broad spectral shape with a distinct emission peak. As the universe expands, and as the observed spectra of galaxies shift to the red, light at the wavelength of this peak moves into the submillimeter band leaving the levels of observed infrared flux deficient. Star-forming galaxies in the very distant universe are thus fainter in the infrared than in the submillimeter.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt. The bar is visible in this image

    Andromeda Galaxy Adam Evans

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Thousands of galaxies have been discovered dating from epochs only a few billion years after the big bang. Most of them are small, low-mass galaxies that are faint and relatively difficult to study. Although more luminous, massive star-forming galaxies should also be present, these large objects are difficult to assemble at early cosmic times and there are not as many of them. One type of such luminous early galaxy is called a dusty-star-forming galaxy. They contain so much obscuring dust that they are invisible at optical wavelengths, and (based on their luminosities) have star-formation rates exceeding a thousand solar-masses per year; for comparison, the Milky Way produces about one star per year.

    Dusty star-forming galaxies in the earliest epochs, less than two billion years after the big bang, are particularly rare and hard to find, but they are extremely valuable in helping understand how the first galaxies develop. CfA astronomer Glen Petitpas was a member of a team of astronomers who used the SCUBA-2 camera (Submillimeter Common User Bolometer Array-2) and the far-infrared Herschel SPIRE instrument to discover and characterize a dusty star-forming galaxy. They serendipitously detected the unusual galaxy in a SCUBA-2 survey. When they realized that the object was not detected by Herschel – or by any other optical or infrared survey, suggesting that its infrared peak had moved very far to the red – they concluded that it likely was from an extremely early epoch.

    1
    SCUBA-2 on the James Clerk Maxwell Telescope


    East Asia Observatory James Clerk Maxwell telescope, Mauna Kea, Hawaii, USA,4,207 m (13,802 ft) above sea level

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

    ESA Herschel Spire Schematic

    ESA Herschel SPIRE

    The team then used the Submillimeter Array, with a spatial resolution about ten times finer than SCUBA-2, to confirm the detection and study the source. Since a firm distance measurement requires detecting a spectral line and measuring its redshift, the scientists also tried using other submillimeter facilities suitable for line searches, but without success. Nevertheless, from the flux limits at various wavelengths they were able to make a strong case that this object is a massive, dusty star-forming galaxy, among the first generation of massive galaxies in the universe and dating from between roughly seven hundred million and one billion years after the big bang.

    Science paper:
    A SCUBA-2 Selected Herschel-Spire Dropout and the Nature of This Population
    MNRAS

    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 8:47 am on December 24, 2019 Permalink | Reply
    Tags: , , , CfA, ,   

    From Harvard-Smithsonian Center for Astrophysics: “Simulating Galactic Outflows” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    Simulating Galactic Outflows

    December 20, 2019

    1
    A face-on disk galaxy from the epoch about six billion years after the big bang. The image was produced with the new IllustrisTNG50 simulation which offers a much finer spatial scale than earlier simulations. the legend insert shows a scale length of 5 kiloparsecs, about sixteen thousand light-years. Nelson, et al. and the IllustrisTNG Project

    Astronomers have known for decades that massive outflows of gas are being ejected from galaxies. These fast-moving, bipolar streams act to slow down the rate of star formation and inhibit the gravitational collapse of the galaxy, and they help to counterbalance the inflow of material from the intergalactic medium. Two physical mechanisms power these outflows, supernovae explosions in star-forming regions and winds produced in the vicinities of the central supermassive blackholes as they accrete material. Understanding these processes is essential to understanding how galaxies develop, but attempts using numerical simulations have been stymied for decades because both star formation and black hole accretion operate at small scales,roughly ten billion times smaller than the scale of the whole galaxy and its host environment. It is computationally very challenging to model both large-scale and small-scale processes with the same code. As a result, cosmological simulations of galaxy evolution developed over the years have not been able to be compared directly to observations of outflows.

    The Illustris project is an international collaboration that has been producing simulated galaxy evolution scenarios for over five years.

    2
    Large scale projection through the Illustris volume at z=0, centered on the most massive cluster, 15 Mpc/h deep. Shows dark matter density overlaid with the gas velocity field.

    The smallest sizes in its simulations are about 2300 light-years and, to describe processes occurring in volumes smaller than that,the code invokes a generic algorithm rather than perform detailed calculations.The project has been extremely successful in being able to reproduce the vast cosmological web of galaxies that developed after the big bang. IllustrisTNG (“the next generation”) is a new version of the Illustris simulation project that partially addresses the scale problem by focusing on detailed consideration of selected small volumes while still capturing the essential large-scale processes. The IllustrisTNG50 simulation, the third and final version in this series, simulates activity in dimensions as small as hundreds of light-years in an overall volume fifty million parsecs (163 million light-years) on a side, offering a unique combination of both large volume and fine resolution.

    CfA astronomers Rainer Weinberger and Lars Hernquist are members of the TNG50 team that has just published its first results. As galaxies become more massive, the outflow rate compared to the star formation rate decreases. However, in moderately large systems, this trend reverses because of the increased influence of the supermassive black hole winds. The scientists also report finding that the outflows are naturally collimated into bipolar shapes, and that the wind velocities increase with galaxy mass to speeds in excess of three thousand kilometers per second. Not least, although galaxies undergoing more active star formation drive faster winds in general, in high mass galaxies in which star formation has been suppressed the winds remain strong because of the activity of the accreting black holes.

    Reference
    “First Results from the TNG50 Simulation: Galactic Outflows Driven by Supernovae and Black Hole Feedback,” Dylan Nelson, Annalisa Pillepich, Volker Springel, Rudiger Pakmor, Rainer Weinberger, Shy Genel, Paul Torrey, Mark Vogelsberger, Federico Marinacci, and Lars Hernquist, 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 8:46 am on December 19, 2019 Permalink | Reply
    Tags: , , , CfA, , Probing the Solar Wind Up Close,   

    From Harvard-Smithsonian Center for Astrophysics: “Probing the Solar Wind Up Close” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    December 13, 2019

    The sun glows with a surface temperature of about 5500 degrees Celsius but its hot outer layer, the corona, has a temperature of over a million degrees. The corona ejects a wind of charged particles, and in 1957 Eugene Parker realized that this wind, already known to be responsible for the direction of comets’ tails, could move faster than the speed of sound and could easily bombard the Earth. He developed a theory for the solar wind, and today that wind is known for producing auroral glows and even disrupting global communications.

    There are two important, longstanding, and related questions about the wind that astronomers have been working to answer: How does the corona become heated to temperatures so much hotter than the surface, and how does the corona generate and then shape the wind as it expels particles into space? The approximate answer to the first question involves the ionized material in the hot corona. The moving gas generates powerful magnetic field loops that, when they twist and break, can accelerate charged particles. The answer to the second question has been even more difficult to ascertain because the solar wind has only been sampled so far by spacecraft whose closest approach to the sun has been about thirty million miles, about the same distance from the sun as the orbit of Mercury. By this distance, however, scientists think that the wind has already undergone changes that obscure key details of its driving sources in the corona.

    In August, 2018, NASA launched the Parker Solar Probe to approach within 3.8 million miles of the sun’s surface in a series of progressively closer approaches to answer this and other pressing questions.

    NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker

    In November 2018 and April 2019 the probe completed its first pass, coming about twice as close to the sun as any previous probe, and the results have just been published in a series of articles in Nature. CfA astronomers Justin Kasper, Anthony Case, Leon Golub, Kelly Korreck, and Michael Stevens, play leadership roles on the Parker team, including development of one of Parker’s instruments, SWEAP (the Solar Wind Electrons Alphas and Protons Investigation). In the new papers, the team demonstrates for the first time that the solar wind near the sun is much more structured and dynamic than it is at Earth. The direction of the magnetic field, for example, undergoes rapid reversals that last for only minutes. Although some similar magnetic field behaviors had been spotted before, the large amplitude and the high occurrence rates of the reversals seen by Parker were surprising. The precise nature of these reverse structures is unknown, but astronomers suspect that plasma instabilities like these play a much larger role in the dynamics and energetics of the solar wind than had previously been expected.

    In related discoveries, the spacecraft found that as the wind streams out into space, parts of it race ahead in high-velocity “rogue” waves with nearly double the speed of the solar wind. Parker flew through more than 1,000 of these spikes; they too are still mysterious. In fact, some particles are apparently being accelerated to speeds nearing the speed of light in events that can be impulsive as well as gradual. A third surprising result was how quickly the solar wind in general rotates around the sun. Models had suggested that the wind flows in this direction at a speed of a few kilometers per second, but the Parker Solar Probe measured it moving much faster, about 35 to 50 kilometers a second. The reason for this is also not known. Parker has several more years to orbit the sun in even closer approaches, and during this time the sun enter a more active phase. These first results have already demonstrated the success of the mission and signal that many more discoveries – and a new understanding of the solar wind – lies ahead.

    Reference(s):
    Alfvénic velocity spikes and rotational flows in the near-Sun solar wind, Nature

    Probing the Energetic Particle Environment Near the Sun, Nature

    Highly Structured Slow Solar Wind Emerging from an Equatorial Coronal Hole, Nature

    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 1:15 pm on November 22, 2019 Permalink | Reply
    Tags: , , , CfA, ,   

    From Harvard-Smithsonian Center for Astrophysics: “Chemistry in the Turbulent Interstellar Medium” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    November 22, 2019

    1
    A multi-wavelength image of a portion of the Perseus molecular cloud, located about 850 light-years away, and its nebulae. Turbulence is pervasive in molecular clouds and plays an important role in producing small density and temperature fluctuations that in turn help determine the abundances of complex molecules in the cloud. A new set of chemical and hydrodynamical models is able to account for the effects of such turbulence and offers an improved explanation for observed chemical abundances. Agrupació Astronòmica d’Eivissa/Ibiza AAE, Alberto Prats Rodríguez

    Over two hundred molecules have been discovered in space, some (like Buckminsterfullerene) very complex with carbon atoms. Besides being intrinsically interesting, these molecules radiate away heat, helping giant clouds of interstellar material cool and contract to form new stars. Moreover, astronomers use the radiation from these molecules to study the local conditions, for example, as planets form in disks around young stars.

    The relative abundance of these molecular species is an important but longstanding puzzle, dependent on many factors from the abundances of the basic elements and the strength of the ultraviolet radiation field to a cloud’s density, temperature, and age. The abundances of the small molecules (those with two or three atoms) are particularly important since they form stepping stones to larger species, and among these the ones that carry a net charge are even more important since they undergo chemical reactions more readily. Current models of the diffuse interstellar medium assume uniform layers of ultraviolet illuminated gas with either a constant density or a density that varies smoothly with depth into the cloud. The problem is that the models’ predictions often disagree with observations.

    Decades of observations have also shown, however, that the interstellar medium is not uniform but rather turbulent, with large variations in density and temperature over small distances. CfA astronomer Shmuel Bialy led a team of scientists investigating the abundances of four key molecules — H2, OH+, H2O+, and ArH+ — in a supersonic (with motions exceeding the speed of sound) and turbulent medium. These particular molecules are both useful astronomical probes and highly sensitive to the density fluctuations that naturally arise in turbulent media. Building on their previous studies of the behavior of molecular hydrogen (H2) in turbulent media, the scientists performed detailed computer simulations that incorporate a wide range of chemical pathways together with models of supersonic turbulent motions under a variety of excitation scenarios driven by ultraviolet radiation and cosmic rays. Their results, when compared to extensive observations of molecules, show good agreement. The range of turbulent conditions is wide and the predictions correspondingly wide, however, so that while the new models do a better job of explaining the observed ranges, they can be ambiguous and explain a particular situation with several different combinations of parameters. The authors make a case for additional observations and a next-generation of models to constrain the conclusions more tightly.

    Science paper:
    The Astrophysical 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.

     
  • richardmitnick 2:06 pm on September 20, 2019 Permalink | Reply
    Tags: , , , CfA, , , , The next-generation Event Horizon Telescope (ngEHT)   

    From Harvard-Smithsonian Center for Astrophysics: “Announcement of the Next Generation Event Horizon Telescope Design Program” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    September 20, 2019
    Tyler Jump
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    +1 617-495-7462
    tyler.jump@cfa.harvard.edu

    1

    The National Science Foundation has just announced the award of a $12.7M grant to architect and design a next-generation Event Horizon Telescope (ngEHT) to carry out a program of transformative black hole science.

    Led by Principal Investigator Shep Doeleman at the Center for Astrophysics | Harvard and Smithsonian (CfA), the new ngEHT award will fund design and prototyping efforts by researchers at several US institutes. These include Dr. Gopal Narayanan at University of Massachusetts, Amherst, Dr. Vincent Fish at the MIT Haystack Observatory, and Drs. Katherine L. (Katie) Bouman and Gregg Hallinan at Caltech. At the CfA, Drs. Michael Johnson, Jonathan Weintroub and Lindy Blackburn are co-Principal Investigators of the ngEHT program.

    On April 10th, 2019, the International Event Horizon Telescope Collaboration released the first image of a supermassive black hole. A bright ring of emission at the heart of the Virgo A galaxy revealed a black hole, known as Messier 87, that has the mass of 6.5 billion Suns.

    Messier 87 supermassive black hole from the EHT

    Einstein’s theory of gravity passed this new test in spectacular fashion in this extreme cosmic laboratory. For this work, the EHT Collaboration will receive the Breakthrough Prize in Fundamental Physics this November.

    Black holes, objects with gravity so strong that light cannot escape, are now accessible to direct imaging. More precise tests of gravity can now be contemplated, and the processes by which supermassive black holes energize the brightness and dynamics of most galaxy cores can be studied in detail. The next-generation EHT (ngEHT) will sharpen the focus on black holes, and let researchers move from still-imagery to real-time videos of space-time at the event horizon.

    “As with all great discoveries, the first black hole image was just the beginning,” says Doeleman, Founding Director of the EHT. “Imagine being able to see a black hole evolve before your eyes. The ngEHT will give us front-row seats to one of the Universe’s most spectacular shows.”

    Sparked by this major investment, the ngEHT is expected to attract additional international support and participation by the broad EHT community. The ngEHT award is aimed at solving the formidable technical and algorithmic challenges required to significantly expand the capability of the EHT.

    The first Messier 87 black hole images were made using the technique of Very Long Baseline Interferometry (VLBI), in which an array of radio dishes around the world is combined to form an Earth-sized virtual telescope.

    Event Horizon Telescope Array

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM 30m Radio telescope, on Pico Veleta in the Spanish Sierra Nevada,, Altitude 2,850 m (9,350 ft)


    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

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

    Submillimeter Array Hawaii SAO

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    Future Array/Telescopes

    IRAM NOEMA in the French Alps on the wide and isolated Plateau de Bure at an elevation of 2550 meters, the telescope currently consists of ten antennas, each 15 meters in diameter.interferometer, Located in the French Alpes on the wide and isolated Plateau de Bure at an elevation of 2550 meters

    NSF CfA Greenland telescope


    Greenland Telescope

    ARO 12m Radio Telescope, Kitt Peak National Observatory, Arizona, USA, Altitude 1,914 m (6,280 ft)


    ARO 12m Radio Telescope

    By exploring new dish designs and locations, the ngEHT effort will plan the architecture for a new array with roughly double the number of sites worldwide.

    “The EHT observations demand unusually dry atmospheric conditions typically found at high altitudes. Identifying sites that meet this demand and deploying new dishes will vastly improve the EHT array’s black hole imaging ability,” says Dr. Jonathan Weintroub.

    In addition to new dishes, the ngEHT will incorporate an existing telescope at Caltech’s Owen’s Valley Radio Observatory (OVRO) and will upgrade the Large Millimeter Telescope Alfonso Serrano (LMT) in Mexico. “With its large aperture and central geographic location, the LMT is crucial to the next generation EHT effort. Planned enhancements to the LMT’s performance using MSRI funds will improve the EHT sensitivity over long observing campaigns,” notes Dr. Gopal Narayanan.

    Caltech Owens Valley Radio Observatory, located near Big Pine, California (US) in Owens Valley, Altitude1,222 m (4,009 ft)

    New technologies will, in turn, allow the ngEHT to expand the swath of radio frequencies it uses to photograph the event horizon. High speed recording systems that capture radio waves from the black hole will transfer data to central locations where they can be merged in a process that is analogous to the mirror in an optical telescope reflecting light to a single focus.

    “Currently, the EHT records about 10 PetaBytes of data each session,” according to Dr. Vincent Fish. “With planned higher data rates and the inclusion of new observatories, EHT data volumes could exceed 100 PetaBytes. Part of this project will be to investigate how to leverage advances in commercial technology to cost-effectively record and transport such a large volume of data.”

    The process of combining and analyzing data from around the globe demands high-performance computers and software that align signals from each EHT site to a fraction of a trillionth of a second. “The ngEHT pushes the boundaries in VLBI data complexity, along with the demands of models that seamlessly link the antennas together into a single Earth-size telescope,” says Dr. Lindy Blackburn.

    By filling in the Earth-sized lens with many new geographic locations, the ngEHT program will be able to harness new powerful algorithms to turn the incredible data volumes into images and even movies.

    “Our own Milky Way is host to a supermassive black hole that evolves dramatically over the course of a night. We are developing new methods, which incorporate emerging ideas from machine learning and computational imaging, in order to make the very first movies of gas spiraling towards an event horizon,” says Dr. Katie Bouman

    The goal of the EHT is to address some of the greatest mysteries and deepest questions about black holes.

    “Despite decades of study, some of the most basic questions about black holes remain untested,” says Dr. Michael Johnson. “With the ngEHT, we will be able to study how black holes act as powerful cosmic engines, energizing a swirling bath of infalling plasma and efficiently pouring unimaginable amounts of energy into narrow jets that pierce entire galaxies.”

    Doeleman is optimistic about the prospects of new discoveries with the ngEHT. “A decade ago we predicted we would be able to see a black hole. Now we estimate that over a billion people have seen the first image, and the Breakthrough Prize shows the impact it is having across the sciences. Through the ngEHT we are setting our sights high again, aiming to bring humanity even closer to the event horizon.”

    Learn more here: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1935980

    From The National Science Foundation:

    The Event Horizon Telescope (EHT) recently made the first direct image of a black hole, an image seen by billions of people around the world. Both the scientific community and the general the public were galvanized by this result. The program funded here is a design project to plan a greatly enhanced EHT (EHT-II), one with 7-8 additional telescopes placed around the world in locations designed to maximize imaging speed, dynamic range, and fidelity. The much faster snapshot mode of this combination will allow rapid tracking of changes near the black hole event horizon, allowing for the first time ever the creation of movies directly showing the dynamics of extreme gravity environments. The greater imaging power will also address long-standing fundamental questions such as how matter is blasted away from a black hole in the form of relativistic jets. Broader impacts include a National Air and Space Museum exhibit, and training of students in instrumentation development.

    Instead of relying on existing large facilities to form the Very Long Baseline Interferometry (VLBI) array, as the existing EHT has done, this design program will consider engineering and placement of small-diameter dishes that optimally fill out an Earth sized virtual telescope, tailored precisely for science objectives. By roughly doubling the number of dishes in the array through cost-effective use of small dishes, the EHT-II will be capable of making the first real-time movies of supermassive black holes. The Large Millimeter Telescope in Mexico, in collaboration with the University of Massachusetts Amherst, will serve as a testbed for advanced dual frequency receivers that will be developed as part of this design initiative.

    This project is supported by the Foundation-wide Mid-scale Research Infrastructure program. The project will be managed by the Division of Astronomical Sciences within the Directorate for Mathematics and Physical Sciences.

    This award reflects NSF’s statutory mission and has been deemed worthy of support through evaluation using the Foundation’s intellectual merit and broader impacts review criteria.

    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 1:16 pm on August 16, 2019 Permalink | Reply
    Tags: "Spotting Merging Galaxies", , , , CfA, , Over thirty years ago the Infrared Astronomy Satellite discovered that the universe contained many extremely luminous galaxies some more than a thousand times brighter than our own Milky Way., These galaxies are practically invisible at optical wavelengths.   

    From Harvard-Smithsonian Center for Astrophysics: “Spotting Merging Galaxies” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    Over thirty years ago, the Infrared Astronomy Satellite discovered that the universe contained many extremely luminous galaxies, some more than a thousand times brighter than our own Milky Way, but which are practically invisible at optical wavelengths.

    1
    NASA Infrared Astronomy Satellite

    These galaxies are powered by bursts of star formation buried deep within clouds of dust and gas. The dust absorbs the ultraviolet light while radiating at infrared wavelengths. In many cases the hyperactivity was triggered by a collisional encounter between galaxies that facilitated the collapse of interstellar gas into new stars.

    Collisions between galaxies are common. Indeed, most galaxies have probably been involved in one or more encounters during their lifetimes, making these interactions an important phase in galaxy evolution and the formation of stars in the universe. The Milky Way, for example, is bound by gravity to the Andromeda galaxy and is approaching it at a speed of about 50 kilometers per second; we are expected to meet in another billion years or so.

    Milkdromeda -Andromeda on the left-Earth’s night sky in 3.75 billion years-NASA

    In the local universe about five percent of galaxies are currently in a merger, and mergers usually can be easily identified by the visible morphological distortions they produce such as tidal tails sweeping out from the galactic discs.

    Not all infrared luminous galaxies show such distortions, however, and the issue of identifying (and classifying) mergers becomes especially problematic for studies of earlier cosmic epochs when the star formation rates were much higher than today, and when the merger rate of galaxies was also higher. (Moreover, such systems are preferentially discovered in deep galaxy surveys precisely because they are so luminous.) But galaxies in the distant cosmos are too remote to detect spatial signatures like tidal arms (at least with current telescopes). It is possible that other processes besides merger-induced star formation are lighting up some of these bright galaxies, for example accreting supermassive black holes can emit copious amounts of ultraviolet radiation. Because of such cases, estimates of star formation in the early universe based on luminosity measurements alone could be incorrect.

    CfA astronomer Lars Hernquist is a pioneer in the development of computer simulations of merging galaxies. Several years ago he and a team of colleagues produced a massive new simulation of the formation and evolution of galaxies in the universe, called Illustris.

    In a new paper [MNRAS] based on Ilustris simulated images of merger galaxies, the astronomers [Gregory F. Snyder, Vicente Rodriguez-Gomez, Jennifer M. Lotz, Paul Torrey, Amanda C.N. Quirk, Lars Hernquist, Mark Vogelsberger and Peter E. Freeman] present a way to help identify when imaged systems are mergers.

    They created about one million synthetic Hubble and James Webb Space Telescope images from their simulated mergers, and then looked for common morphological indicators of merging. They developed an algorithm that successfully identified mergers at roughly a seventy percent level of completeness out to distances of as much as eighty-five billion light-years (the current distance value), corresponding to light dating from the epoch about 2 billion years after the big bang.

    Results from the algorithm indicated that spatial features associated with strong central concentrations (or bulges) were most important for selecting past mergers, while double nuclei and asymmetries were most important for selecting future mergers (that is, sometime in the next 250 million years). The new algorithm will be particularly valuable when applied to future Webb images of very distant mergers.

    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 1:06 pm on July 30, 2019 Permalink | Reply
    Tags: "A Stellar Stream in the Milky Way Provides Evidence of Dark Substructure", , , , CfA, ,   

    From Harvard-Smithsonian Center for Astrophysics: “A Stellar Stream in the Milky Way Provides Evidence of Dark Substructure” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    July 29, 2019
    Amy Oliver, Public Affairs Officer
    amy.oliver@cfa.harvard.edu
    +1-520-879-4406
    mobile: +1-801-783-9067

    1
    The colors of the stars in this GD-1 stellar stream model overlaid on a Gaia flux map show how the star’s orbits were affected by the impact of the unknown dark substructure with white representing a large difference and dark red representing almost no difference. The stream’s orbit is overplotted in the foreground. Ana Bonaca, ESA, Gaia.

    Scientists at the Center for Astrophysics | Harvard & Smithsonian have observed what may be evidence of dark matter interfering with a stellar stream in the Milky Way galaxy.

    For scientists and non-scientists alike, the discovery tells an exciting, edge-of-your-seat story. “We know that 90% of the mass in our universe is invisible. We don’t know what it is, but we’re curious,” said Dr. Ana Bonaca, ITC Fellow at the CfA and lead author of the study. “Stellar streams, which are what we’re studying here, tell us the story of our galaxy. They are so long and thin that they are sensitive to the tiniest disturbances as they orbit through the galaxy. Our findings are that…in action.”

    Gaia, a mission of the European Space Agency (ESA), had a second data release in April 2018, which provided the basis for a new study of GD-1, the longest and most visible thin stellar stream in the Milky Way.

    ESA/GAIA satellite

    Typically, stars are distributed close to uniformly along such streams, so scientists immediately noticed that some of the stars in the GD-1 stream were not behaving as expected.

    “Stellar streams were thought to be more or less smooth in appearance, but GD-1 has gaps or regions of lower density along the stream. Close to one of these gaps there is an offshoot of misaligned stars,” said Adrian Price-Whelan, a coauthor of the study. “So first, we found something interesting that didn’t match what we expected to see, thanks to Gaia.”

    Stellar streams are associations of stars that once previously belonged to a dwarf galaxy or a globular cluster, but that were pulled out by the Milky Way’s tidal forces and stretched out into streams. In the standard picture, these streams are long, thin, and regular. The observed behavior in GD-1, however, could not be explained by tidal forces alone. Instead, Bonaca and collaborators used numerical simulations to show that the observed gap and spur features could be the result of the stream encountering a dense, massive object.

    “We considered a number of different objects as potential sources of perturbation, but none of them seemed to fit. We looked at the orbits of all known satellites in the Galaxy, but none crossed paths with GD-1 recently. We also considered whether molecular clouds could have done the damage because GD-1 crosses the Milky Way disk, but found they are not dense enough,” said Bonaca. “There is no obvious culprit.”

    With no known culprits, scientists have turned to more exotic explanations, and that’s big news for dark matter theorists. “One of the fundamental predictions of the dark-matter model is that there ought to be many concentrations or clusters of dark matter orbiting in the outskirts of our Galaxy. This stream looks like it can be used to find those small clumps of dark matter,” said David Hogg, a coauthor of the study. “Ruling out all other possibilities and actually detecting a small clump of dark matter would be a huge clue for understanding the nature of this important component of the Universe.”

    While Gaia data was used to make initial observations, the team has since conducted follow-up observations with Hectochelle—a multi-object echelle spectrograph—at the MMT Observatory, located at the Fred Lawrence Whipple Observatory at Mt. Hopkins in Arizona.


    CfA U Arizona Fred Lawrence Whipple Observatory Steward Observatory MMT Telescope at the summit of Mount Hopkins near Tucson, Arizona, USA, Altitude 2,616 m (8,583 ft)

    CfA Whipple Observatory, located near Amado, Arizona on the slopes of Mount Hopkins, Altitude 2,606 m (8,550 ft)

    These new data will help in locating the dark substructure. In addition, Bonaca and other scientists have begun observing other stellar streams with unusual features.

    “When something passes close to a stellar stream, it leaves evidence behind, and we can see that something happened there. Even if it’s dark matter. Even if it’s invisible,” said Bonaca. “And if it is a clump of dark matter, there should be many of them. So we’re setting out to search for such oddities in other streams to find out for sure.”

    The results of the study are published in The Astrophysical Journal. In addition to Bonaca, the team consisted of CfA scientist Charlie Conroy; David W. Hogg representing the Centers for Cosmology and Particle Physics and for Data Science at New York University, Max-Planck-Institut fur Astronomie, and Flatiron Institute; and Adrian M. Price-Whelan at Princeton University and the Flatiron Institute.

    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 3:27 pm on July 23, 2019 Permalink | Reply
    Tags: , , , CfA, ,   

    From NASA Chandra Blog: “Exploring New Paths of Study with Chandra” 

    NASA Chandra Banner

    NASA/Chandra Telescope


    From NASA Chandra Blog

    2019-07-22
    Peter Edmonds, CXC

    1
    NASA/Chandra
    We make progress in astrophysics in a variety of ways. There is the sort that starts along a defined path, driven by meticulous proposals for telescope time or detailed science justifications for new missions. The plan is to advance knowledge by traveling further than others, or clearing a broader path. And then there are others.

    A big mission like NASA’s Chandra X-ray Observatory begins with plans for investigation along a slew of different directions and lines of study. At the time of Chandra’s launch on July 23rd, 1999, scientists thought these paths would mainly follow studies of galaxy clusters, dark matter, black holes, supernovas, and young stars. Indeed, in the last 20 years we’ve learned about black holes ripping stars apart (reported eg in 2004, 2011 and 2017), about a black hole generating the deepest known note in the universe, about dark matter being wrenched apart from normal matter in the famous Bullet Cluster and similar objects, about the discovery of the youngest supernova remnant in our galaxy, and much more.

    Bullet Cluster NASA Chandra NASA ESA Hubble


    NASA/ESA Hubble Telescope

    Progress in astrophysics can also be made when new paths of study suddenly open up. Three outstanding examples for Chandra are studies of gravitational wave events, dark energy and exoplanets. None of these fields existed before Chandra was conceived or built, but have now delivered some of our most exciting results.

    2
    Release: NASA Missions Catch FirstLight from a Gravitational-Wave Event

    The newest example is the study of X-rays produced by the aftermath of gravitational wave events. In 1999 the detection of gravitational waves seemed like a distant or even impossible goal for many astronomers. But the LIGO scientists kept improving their remarkably sensitive observatory until September 2015, when they detected a burst of gravitational waves from the merger of two black holes. Two black holes that merge are not expected to produce electromagnetic radiation, but the mergers of two neutron stars are. That is exactly what was as observed for the first time in August 2017 with LIGO and a slew of telescopes.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger

    Gravity is talking. Lisa will listen. Dialogos of Eide

    ESA/eLISA the future of gravitational wave research

    Localizations of gravitational-wave signals detected by LIGO in 2015 (GW150914, LVT151012, GW151226, GW170104), more recently, by the LIGO-Virgo network (GW170814, GW170817). After Virgo came online in August 2018


    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    UC Santa Cruz

    UC Santa Cruz

    UCSC All the Gold in the Universe

    A UC Santa Cruz special report

    Tim Stephens

    Astronomer Ryan Foley says “observing the explosion of two colliding neutron stars” –the first visible event ever linked to gravitational waves–is probably the biggest discovery he’ll make in his lifetime. That’s saying a lot for a young assistant professor who presumably has a long career still ahead of him.

    The first optical image of a gravitational wave source was taken by a team led by Ryan Foley of UC Santa Cruz using the Swope Telescope at the Carnegie Institution’s Las Campanas Observatory in Chile. This image of Swope Supernova Survey 2017a (SSS17a, indicated by arrow) shows the light emitted from the cataclysmic merger of two neutron stars. (Image credit: 1M2H Team/UC Santa Cruz & Carnegie Observatories/Ryan Foley)

    Carnegie Institution Swope telescope at Las Campanas, Chile, 100 kilometres (62 mi) northeast of the city of La Serena. near the north end of a 7 km (4.3 mi) long mountain ridge. Cerro Las Campanas, near the southern end and over 2,500 m (8,200 ft) high, at Las Campanas, Chile

    A neutron star forms when a massive star runs out of fuel and explodes as a supernova, throwing off its outer layers and leaving behind a collapsed core composed almost entirely of neutrons. Neutrons are the uncharged particles in the nucleus of an atom, where they are bound together with positively charged protons. In a neutron star, they are packed together just as densely as in the nucleus of an atom, resulting in an object with one to three times the mass of our sun but only about 12 miles wide.

    “Basically, a neutron star is a gigantic atom with the mass of the sun and the size of a city like San Francisco or Manhattan,” said Foley, an assistant professor of astronomy and astrophysics at UC Santa Cruz.

    These objects are so dense, a cup of neutron star material would weigh as much as Mount Everest, and a teaspoon would weigh a billion tons. It’s as dense as matter can get without collapsing into a black hole.

    THE MERGER

    Like other stars, neutron stars sometimes occur in pairs, orbiting each other and gradually spiraling inward. Eventually, they come together in a catastrophic merger that distorts space and time (creating gravitational waves) and emits a brilliant flare of electromagnetic radiation, including visible, infrared, and ultraviolet light, x-rays, gamma rays, and radio waves. Merging black holes also create gravitational waves, but there’s nothing to be seen because no light can escape from a black hole.

    Foley’s team was the first to observe the light from a neutron star merger that took place on August 17, 2017, and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).

    ALL THE GOLD IN THE UNIVERSE

    It turns out that the origins of the heaviest elements, such as gold, platinum, uranium—pretty much everything heavier than iron—has been an enduring conundrum. All the lighter elements have well-explained origins in the nuclear fusion reactions that make stars shine or in the explosions of stars (supernovae). Initially, astrophysicists thought supernovae could account for the heavy elements, too, but there have always been problems with that theory, says Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz.

    The violent merger of two neutron stars is thought to involve three main energy-transfer processes, shown in this diagram, that give rise to the different types of radiation seen by astronomers, including a gamma-ray burst and a kilonova explosion seen in visible light. (Image credit: Murguia-Berthier et al., Science)

    A theoretical astrophysicist, Ramirez-Ruiz has been a leading proponent of the idea that neutron star mergers are the source of the heavy elements. Building a heavy atomic nucleus means adding a lot of neutrons to it. This process is called rapid neutron capture, or the r-process, and it requires some of the most extreme conditions in the universe: extreme temperatures, extreme densities, and a massive flow of neutrons. A neutron star merger fits the bill.

    Ramirez-Ruiz and other theoretical astrophysicists use supercomputers to simulate the physics of extreme events like supernovae and neutron star mergers. This work always goes hand in hand with observational astronomy. Theoretical predictions tell observers what signatures to look for to identify these events, and observations tell theorists if they got the physics right or if they need to tweak their models. The observations by Foley and others of the neutron star merger now known as SSS17a are giving theorists, for the first time, a full set of observational data to compare with their theoretical models.

    According to Ramirez-Ruiz, the observations support the theory that neutron star mergers can account for all the gold in the universe, as well as about half of all the other elements heavier than iron.

    RIPPLES IN THE FABRIC OF SPACE-TIME

    Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity, but until recently they were impossible to observe. LIGO’s extraordinarily sensitive detectors achieved the first direct detection of gravitational waves, from the collision of two black holes, in 2015. Gravitational waves are created by any massive accelerating object, but the strongest waves (and the only ones we have any chance of detecting) are produced by the most extreme phenomena.

    Two massive compact objects—such as black holes, neutron stars, or white dwarfs—orbiting around each other faster and faster as they draw closer together are just the kind of system that should radiate strong gravitational waves. Like ripples spreading in a pond, the waves get smaller as they spread outward from the source. By the time they reached Earth, the ripples detected by LIGO caused distortions of space-time thousands of times smaller than the nucleus of an atom.

    The rarefied signals recorded by LIGO’s detectors not only prove the existence of gravitational waves, they also provide crucial information about the events that produced them. Combined with the telescope observations of the neutron star merger, it’s an incredibly rich set of data.

    LIGO can tell scientists the masses of the merging objects and the mass of the new object created in the merger, which reveals whether the merger produced another neutron star or a more massive object that collapsed into a black hole. To calculate how much mass was ejected in the explosion, and how much mass was converted to energy, scientists also need the optical observations from telescopes. That’s especially important for quantifying the nucleosynthesis of heavy elements during the merger.

    LIGO can also provide a measure of the distance to the merging neutron stars, which can now be compared with the distance measurement based on the light from the merger. That’s important to cosmologists studying the expansion of the universe, because the two measurements are based on different fundamental forces (gravity and electromagnetism), giving completely independent results.

    “This is a huge step forward in astronomy,” Foley said. “Having done it once, we now know we can do it again, and it opens up a whole new world of what we call ‘multi-messenger’ astronomy, viewing the universe through different fundamental forces.”

    IN THIS REPORT

    Neutron stars
    A team from UC Santa Cruz was the first to observe the light from a neutron star merger that took place on August 17, 2017 and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO)

    Graduate students and post-doctoral scholars at UC Santa Cruz played key roles in the dramatic discovery and analysis of colliding neutron stars.Astronomer Ryan Foley leads a team of young graduate students and postdoctoral scholars who have pulled off an extraordinary coup. Following up on the detection of gravitational waves from the violent merger of two neutron stars, Foley’s team was the first to find the source with a telescope and take images of the light from this cataclysmic event. In so doing, they beat much larger and more senior teams with much more powerful telescopes at their disposal.

    “We’re sort of the scrappy young upstarts who worked hard and got the job done,” said Foley, an untenured assistant professor of astronomy and astrophysics at UC Santa Cruz.

    David Coulter, graduate student

    The discovery on August 17, 2017, has been a scientific bonanza, yielding over 100 scientific papers from numerous teams investigating the new observations. Foley’s team is publishing seven papers, each of which has a graduate student or postdoc as the first author.

    “I think it speaks to Ryan’s generosity and how seriously he takes his role as a mentor that he is not putting himself front and center, but has gone out of his way to highlight the roles played by his students and postdocs,” said Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz and the most senior member of Foley’s team.

    “Our team is by far the youngest and most diverse of all of the teams involved in the follow-up observations of this neutron star merger,” Ramirez-Ruiz added.

    Charles Kilpatrick, postdoctoral scholar

    Charles Kilpatrick, a 29-year-old postdoctoral scholar, was the first person in the world to see an image of the light from colliding neutron stars. He was sitting in an office at UC Santa Cruz, working with first-year graduate student Cesar Rojas-Bravo to process image data as it came in from the Swope Telescope in Chile. To see if the Swope images showed anything new, he had also downloaded “template” images taken in the past of the same galaxies the team was searching.

    Ariadna Murguia-Berthier, graduate student

    “In one image I saw something there that was not in the template image,” Kilpatrick said. “It took me a while to realize the ramifications of what I was seeing. This opens up so much new science, it really marks the beginning of something that will continue to be studied for years down the road.”

    At the time, Foley and most of the others in his team were at a meeting in Copenhagen. When they found out about the gravitational wave detection, they quickly got together to plan their search strategy. From Copenhagen, the team sent instructions to the telescope operators in Chile telling them where to point the telescope. Graduate student David Coulter played a key role in prioritizing the galaxies they would search to find the source, and he is the first author of the discovery paper published in Science.

    Matthew Siebert, graduate student

    “It’s still a little unreal when I think about what we’ve accomplished,” Coulter said. “For me, despite the euphoria of recognizing what we were seeing at the moment, we were all incredibly focused on the task at hand. Only afterward did the significance really sink in.”

    Just as Coulter finished writing his paper about the discovery, his wife went into labor, giving birth to a baby girl on September 30. “I was doing revisions to the paper at the hospital,” he said.

    It’s been a wild ride for the whole team, first in the rush to find the source, and then under pressure to quickly analyze the data and write up their findings for publication. “It was really an all-hands-on-deck moment when we all had to pull together and work quickly to exploit this opportunity,” said Kilpatrick, who is first author of a paper comparing the observations with theoretical models.

    César Rojas Bravo, graduate student

    Graduate student Matthew Siebert led a paper analyzing the unusual properties of the light emitted by the merger. Astronomers have observed thousands of supernovae (exploding stars) and other “transients” that appear suddenly in the sky and then fade away, but never before have they observed anything that looks like this neutron star merger. Siebert’s paper concluded that there is only a one in 100,000 chance that the transient they observed is not related to the gravitational waves.

    Ariadna Murguia-Berthier, a graduate student working with Ramirez-Ruiz, is first author of a paper synthesizing data from a range of sources to provide a coherent theoretical framework for understanding the observations.

    Another aspect of the discovery of great interest to astronomers is the nature of the galaxy and the galactic environment in which the merger occurred. Postdoctoral scholar Yen-Chen Pan led a paper analyzing the properties of the host galaxy. Enia Xhakaj, a new graduate student who had just joined the group in August, got the opportunity to help with the analysis and be a coauthor on the paper.

    Yen-Chen Pan, postdoctoral scholar

    “There are so many interesting things to learn from this,” Foley said. “It’s a great experience for all of us to be part of such an important discovery.”

    Enia Xhakaj, graduate student

    IN THIS REPORT

    Scientific Papers from the 1M2H Collaboration

    Coulter et al., Science, Swope Supernova Survey 2017a (SSS17a), the Optical Counterpart to a Gravitational Wave Source

    Drout et al., Science, Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis

    Shappee et al., Science, Early Spectra of the Gravitational Wave Source GW170817: Evolution of a Neutron Star Merger

    Kilpatrick et al., Science, Electromagnetic Evidence that SSS17a is the Result of a Binary Neutron Star Merger

    Siebert et al., ApJL, The Unprecedented Properties of the First Electromagnetic Counterpart to a Gravitational-wave Source

    Pan et al., ApJL, The Old Host-galaxy Environment of SSS17a, the First Electromagnetic Counterpart to a Gravitational-wave Source

    Murguia-Berthier et al., ApJL, A Neutron Star Binary Merger Model for GW170817/GRB170817a/SSS17a

    Kasen et al., Nature, Origin of the heavy elements in binary neutron star mergers from a gravitational wave event

    Abbott et al., Nature, A gravitational-wave standard siren measurement of the Hubble constant (The LIGO Scientific Collaboration and The Virgo Collaboration, The 1M2H Collaboration, The Dark Energy Camera GW-EM Collaboration and the DES Collaboration, The DLT40 Collaboration, The Las Cumbres Observatory Collaboration, The VINROUGE Collaboration & The MASTER Collaboration)

    Abbott et al., ApJL, Multi-messenger Observations of a Binary Neutron Star Merger

    PRESS RELEASES AND MEDIA COVERAGE


    Watch Ryan Foley tell the story of how his team found the neutron star merger in the video below. 2.5 HOURS.

    Press releases:

    UC Santa Cruz Press Release

    UC Berkeley Press Release

    Carnegie Institution of Science Press Release

    LIGO Collaboration Press Release

    National Science Foundation Press Release

    Media coverage:

    The Atlantic – The Slack Chat That Changed Astronomy

    Washington Post – Scientists detect gravitational waves from a new kind of nova, sparking a new era in astronomy

    New York Times – LIGO Detects Fierce Collision of Neutron Stars for the First Time

    Science – Merging neutron stars generate gravitational waves and a celestial light show

    CBS News – Gravitational waves – and light – seen in neutron star collision

    CBC News – Astronomers see source of gravitational waves for 1st time

    San Jose Mercury News – A bright light seen across the universe, proving Einstein right

    Popular Science – Gravitational waves just showed us something even cooler than black holes

    Scientific American – Gravitational Wave Astronomers Hit Mother Lode

    Nature – Colliding stars spark rush to solve cosmic mysteries

    National Geographic – In a First, Gravitational Waves Linked to Neutron Star Crash

    Associated Press – Astronomers witness huge cosmic crash, find origins of gold

    Science News – Neutron star collision showers the universe with a wealth of discoveries

    UCSC press release
    First observations of merging neutron stars mark a new era in astronomy

    Credits

    Writing: Tim Stephens
    Video: Nick Gonzales
    Photos: Carolyn Lagattuta
    Header image: Illustration by Robin Dienel courtesy of the Carnegie Institution for Science
    Design and development: Rob Knight
    Project managers: Sherry Main, Scott Hernandez-Jason, Tim Stephens

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


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

    Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet

    Noted in the video but not in the article:

    NASA/Chandra Telescope

    NASA/SWIFT Telescope

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    Prompt telescope CTIO Chile

    NASA NuSTAR X-ray telescope

    See the full article here

    A Chandra observation two days after the merger failed to make a detection, but about a week later a source was discovered. These and additional observations taught us about the behavior and orientation of the jet that the neutron star merger produced.

    The interest in this X-ray detection was so intense that there was a race between three different teams to publish the early Chandra observations first. This was accompanied by a rush to publicly announce the full set of results from LIGO and telescopes across the electromagnetic spectrum, before too many smart science writers dug out the news from Twitter and other publicly available information.

    3
    Release: All in the Family: Kin ofGravitational-Wave Source Discovered

    Chandra detections of two likely neutron star mergers have been reported since August 2017 (in 2018 and 2019). These did not involve a detection of GWs, both because Advanced LIGO wasn’t yet operating, and because the events were likely too distant to be detectable even if it was. When Advanced LIGO and Virgo detect other neutron star mergers, and optical telescopes track them down, Chandra “Target of Opportunity” programs will kick in to study them. (TOOs, as they are called, are special cases made by scientists to interrupt the regularly scheduled observations in favor of one that is time sensitive and/or extremely important.) One is a large proposal and collaboration between three different teams, one aims to take a spectrum, another aims to observe a relatively nearby event, and a fourth involves joint observations with the VLA.

    Those who work on Chandra and many in the wider science community were very excited about this detection because it marked the first time that gravitational waves and electromagnetic radiation were observed together, as a new type of “multi-messenger” astrophysics. (Multi-messenger astrophysics involves at least two of the following messengers: electromagnetic radiation, gravitational waves, neutrinos and cosmic rays.) However, it did not represent the first instance of multi-messenger astrophysics, because both electromagnetic radiation and neutrinos had already been observed from the Sun and from Supernova 1987A. Chandra may have already got into the act with the observation of a flare from material very close to the supermassive black hole in the center of our Galaxy, as reported in 2014. An energetic neutrino observed with the IceCube detector may have originated from this flare.

    Another exciting new line of study has come from the discovery that the expansion of the universe is accelerating. The two key papers providing the first evidence for this surprising result were published in 1998 and 1999, just before Chandra launched. Both papers used distance measurements to supernova explosions over the last 5 billion or so years to follow the expansion. Since then a set of different techniques have been used to independently confirm and extend these results, including two involving Chandra observations of galaxy clusters. In one of them the distances to galaxy clusters were used to probe the expansion rate of the universe and another involved measuring the effects of accelerating expansion in slowing down the growth rate of galaxy clusters, in a type of cosmic arrested development. As explained in this article, if it wasn’t for accelerating expansion the universe would look very different from how it looks today.

    The work measuring the growth rate of galaxy clusters has led to independent tests of Einstein’s General Theory of Relativity over distances that are much greater than those of Earth-orbiting satellites. The confirmation of GR has added to the evidence that a mysterious force called “dark energy” is causing cosmic acceleration.

    4
    Release: Astronomers Find Dark EnergyMay Vary Over Time

    More recently, Chandra is being used with a new technique to probe cosmic expansion out to greater distances than are possible with supernova data. Astronomers have found tentative evidence that dark energy might be strengthening with time, but this result needs to be confirmed with more extensive use of Chandra data, a study that is currently underway, and independent work.

    The recently-launched European mission eROSITA will be taking a sensitive X-ray survey of the complete sky and will discover a huge number of galaxy clusters for follow-up studies of both dark energy and dark matter with Chandra.

    eRosita DLR MPG

    5
    Release: NASA’s Chandra Sees Eclipsing Planetin X-rays for First Time

    Many think the field of exoplanets studies started in 1995 with the detection of a hot Jupiter around the star 51 Pegasus, acclaimed as the first exoplanet discovered around a Sun-like star. (This was about the time that the grinding and polishing of Chandra’s grazing-incidence mirrors was completed.) Chandra observations have shown cases of the tail wagging the dog, where a planet is affecting the star it is orbiting, in one case by making the star appear unusually old, and in others causing it to behave like a much younger star, as reported in 2011 and 2013.

    Chandra observations have uncovered multiple examples of planets under assault by outside forces. They’ve found cases where radiation from the host star is evaporating the atmosphere of a close-in planet (from 2011 and 2013), where the powerful gravity of a white dwarf may have ripped a planet apart, a case of possible stellar or planetary cannibalism, and a case where a star may be devouring a young planet. Chandra data was also used to show that young stars much less massive than the Sun can unleash a torrent of X-ray radiation that may significantly shorten the lifetime of planet-forming disks surrounding these stars.

    We look forward to reporting more results in these three new fields, along with discoveries from X-ray astronomy’s traditional specialities. We also hope to see new fields appear, for fresh exploration with NASA’s premier X-ray mission.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

     
  • richardmitnick 1:06 pm on June 25, 2019 Permalink | Reply
    Tags: "The Low Density of Some Exoplanets is Confirmed", , , , CfA, , Kepler-9 and its planets Kepler-9b and Kepler-9c   

    From Harvard-Smithsonian Center for Astrophysics: “The Low Density of Some Exoplanets is Confirmed” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    June 21, 2019

    The Kepler mission and its extension, called K2, discovered thousands of exoplanets.

    NASA/Kepler Telescope, and K2 March 7, 2009 until November 15, 2018

    It detected them using the transit technique, measuring the dip in light intensity whenever an orbiting planet moved across the face of its host star as viewed from Earth.

    Planet transit. NASA/Ames

    Transits can not only measure the orbital period, they often can determine the size of the exoplanet from the detailed depth and shape of its transit curve and the host star’s properties. The transit method, however, does not measure the mass of the planet. The radial velocity method, by contrast, which measures the wobble of a host star under the gravitational pull of an orbiting exoplanet, allows for the measurement of its mass. Knowing a planet’s radius and mass allows for the determination of its average density, and hence clues to its composition.

    Radial Velocity Method-Las Cumbres Observatory

    About fifteen years ago, CfA astronomers and others realized that in planetary systems with multiple planets, the periodic gravitational tug of one planet on another will alter their orbital parameters. Although the transit method cannot directly measure exoplanet masses, it can detect these orbital variations and these can be modeled to infer masses. Kepler has identified hundreds of exoplanet systems with transit-timing variations, and dozens have been successfully modeled. Surprisingly, this procedure seemed to find a prevalence of exoplanets with very low densities. The Kepler-9 system, for example, appears to have two planets with densities respectively of 0.42 and 0.31 grams per cubic centimeter. (For comparison, the rocky Earth’s average density is 5.51 grams per cubic centimeter, water is, by definition, 1.0 grams per cubic centimeter, and the gas giant Saturn is 0.69 grams per cubic centimeter.) The striking results cast some doubt on one or more parts of the transit timing variation methodology and created a long-standing concern.

    CfA astronomers David Charbonneau, David Latham, Mercedes Lopez-Morales, and David Phillips, and their colleagues tested the reliability of the method by measuring the densities of the Kepler-9 planets using the radial velocity method, its two Saturn-like planets being among a small group of exoplanets whose masses can be measured (if just barely) with either technique.

    2
    An artist’s depiction of Kepler-9 and its planets Kepler-9b and Kepler-9c. NASA

    They used the HARPS-N spectrometer on the Telescopio Nazionale Galileo in La Palma in sixteen observing epochs; HARPS-N can typically measure velocity variations with an error as tiny as about twenty miles an hour. Their results confirm the very low densities obtained by the transit-timing method, and verify the power of the transit-variation method.

    Harps North at Telescopio Nazionale Galileo –

    Telescopio Nazionale Galileo a 3.58-meter Italian telescope, located at the Roque de los Muchachos Observatory on the island of La Palma in the Canary Islands, Spain, Altitude 2,396 m (7,861 ft)

    Science paper:
    HARPS-N Radial Velocities Confirm the Low Densities of the Kepler-9 Planets
    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 2:57 pm on June 7, 2019 Permalink | Reply
    Tags: "The Co-Evolution of Galaxies and Supermassive Black Holes", , , , CfA,   

    From Harvard-Smithsonian Center for Astrophysics: “The Co-Evolution of Galaxies and Supermassive Black Holes” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    1
    An Illustris-TNG simulation of the stellar content of the universe today on the largest scales showing a projection of stars across a 150 million light-years. Scientists using the code have been able to trace the co-evolution of galaxies and their supermassive black holes. The TNG Collaboration

    The formation and growth of galaxies in the early universe is a key research topic for future giant telescopes like the Giant Magellan Telescope and space missions like the James Webb Space Telescope.

    Giant Magellan Telescope, to be at the Carnegie Institution for Science’s Las Campanas Observatory, to be built some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high

    NASA/ESA/CSA Webb Telescope annotated

    Meanwhile, computer simulations of cosmic galaxy development have made considerable progress in our understanding. They show that details of galaxy development are closely tied to the properties of the galaxies, like their sizes and star formation rates. These properties are in turn regulated by the galaxies’ gas content, the gas motions (primarily the angular momentum), and some still uncertain mechanisms that regulate star formation like feedback from the nuclear black hole. Finally, there is growing evidence for correlations between the properties of a supermassive black hole and its host galaxy.

    Black holes with millions or even billions of solar masses are found in the centers of most galaxies. The most powerfully active nuclear black holes are in quasars and these have been spotted as far away as the epoch when the universe was less than a billion years old, suggesting that the galaxy- black hole symbiosis was already underway at this early time. Accreting black holes can emit powerful jets or winds that reverse the accretion and drive material outward, sometimes quenching the star formation. These and other lines of evidence help to clarify the co-evolution mechanisms between black holes and galaxies and reveal the joint evolution of the galaxy and the supermassive black hole populations.

    CfA astronomers Lars Hernquist and Rainer Weinberger and their colleagues used the large-scale hydrodynamic simulation called IllustrisTNG to trace the development of galaxies and their black holes. The code is able to model the evolution of a wide range of black hole and galaxy properties as the universe ages. They successfully reproduce the observed correlation between star formation rate and galaxy mass. They find, among numerous other trends, that quiescent galaxies (those no longer actively making stars) first go through a phase of shrinking in size before they undergo a quenching event; they also find that in the cosmic epoch of peak star formation (about ten billion years ago) as many as twenty percent of galaxies hosted an active supermassive black hole.

    science paper:
    Linking Galaxy Structural Properties and Star Formation Activity to Black Hole Activity with 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.

     
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