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  • richardmitnick 3:23 pm on May 11, 2017 Permalink | Reply
    Tags: , , , , , Supermassive Black Holes   

    From Chandra: “Astronomers Pursue Renegade Supermassive Black Hole” 

    NASA Chandra Banner

    NASA Chandra Telescope

    NASA Chandra

    2017-05-09

    1
    CXO J101527.2+625911

    Supermassive holes are generally stationary objects, sitting at the centers of most galaxies. However, using data from NASA’s Chandra X-ray Observatory and other telescopes, astronomers recently hunted down what could be a supermassive black hole that may be on the move.

    This possible renegade black hole, which contains about 160 million times the mass of our Sun, is located in an elliptical galaxy about 3.9 billion light years from Earth. Astronomers are interested in these moving supermassive black holes because they may reveal more about the properties of these enigmatic objects.

    This black hole may have “recoiled,” in the terminology used by scientists, when two smaller supermassive black holes collided and merged to form an even larger one. At the same time, this collision would have generated gravitational waves that emitted more strongly in one direction than others. This newly formed black hole could have received a kick in the opposite direction of those stronger gravitational waves. This kick would have pushed the black hole out of the galaxy’s center, as depicted in the artist’s illustration.

    The strength of the kick depends on the rate and direction of spin of the two smaller black holes before they merge. Therefore, information about these important but elusive properties can be obtained by studying the speed of recoiling black holes.

    Astronomers found this recoiling black hole candidate by sifting through X-ray and optical data for thousands of galaxies. First, they used Chandra observations to select galaxies that contain a bright X-ray source and were observed as part of the Sloan Digital Sky Survey (SDSS).

    SDSS Telescope at Apache Point Observatory, NM, USA

    Bright X-ray emission is a common feature of supermassive black holes that are rapidly growing.

    Next, the researchers looked to see if Hubble Space Telescope observations of these X-ray bright galaxies revealed two peaks near their center in the optical image.

    NASA/ESA Hubble Telescope

    These two peaks might show that a pair of supermassive black holes is present or that a recoiling black hole has moved away from the cluster of stars in the center of the galaxy.

    If those criteria were met, then the astronomers examined the SDSS spectra, which show how the amount of optical light varies with wavelength. If the researchers found telltale signatures in the spectra indicative of the presence of a supermassive black hole, they followed up with an even closer examination of those galaxies.

    After all of this searching, a good candidate for a recoiling black hole was discovered. The left image in the inset is from the Hubble data, which shows two bright points near the middle of the galaxy. One of them is located at the center of the galaxy and the other is located about 3,000 light years away from the center. The latter source shows the properties of a growing supermassive black hole and its position matches that of a bright X-ray source detected with Chandra (right image in inset). Using data from the SDSS and the Keck telescope in Hawaii, the team determined that the growing black hole located near, but visibly offset from, the center of the galaxy has a velocity that is different from the galaxy.


    Keck Observatory, Mauna Kea, Hawaii, USA

    These properties suggest that this source may be a recoiling supermassive black hole.

    The host galaxy of the possible recoiling black hole also shows some evidence of disturbance in its outer regions, which is an indication that a merger between two galaxies occurred in the relatively recent past. Since supermassive black hole mergers are thought to occur when their host galaxies merge, this information supports the idea of a recoiling black hole in the system.

    Moreover, stars are forming at a high rate in the galaxy, at several hundred times the mass of the Sun per year. This agrees with computer simulations, which predict that star formation rates may be enhanced for merging galaxies particularly those containing recoiling black holes.

    Another possible explanation for the data is that two supermassive black holes are located in the center of the galaxy but one of them is not producing detectable radiation because it is growing too slowly. The researchers favor the recoiling black hole explanation, but more data are needed to strengthen their case.

    A paper describing these results was recently accepted for publication in The Astrophysical Journal and is available online. The first author is Dongchan Kim from the National Radio Astronomy Observatory in Charlottesville, Virginia.

    See the full article here .

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    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 7:35 am on April 28, 2017 Permalink | Reply
    Tags: , , , , Quasar pairs, , Ripples in cosmic web measured using rare double quasars, , Supermassive Black Holes,   

    From UCSC: “Ripples in cosmic web measured using rare double quasars” 

    UC Santa Cruz

    UC Santa Cruz

    [PREVIOUSLY COVERED HERE .]

    April 27, 2017
    Julie Cohen
    stephens@ucsc.edu

    1
    Astronomers identified rare pairs of quasars right next to each other on the sky and measured subtle differences in the absorption of intergalactic atoms measured along the two sightlines. This enabled them to detect small-scale fluctuations in primeval hydrogen gas.(Credit: UC Santa Barbara)

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    Snapshot of a supercomuter simulation showing part of the cosmic web, 11.5 billion years ago. The researchers created this and other models of the universe and directly compared them with quasar pair data in order to measure the small-scale ripples in the cosmic web. The cube is 24 million light-years on a side. © J. Oñorbe / MPIA

    The most barren regions of the universe are the far-flung corners of intergalactic space. In these vast expanses between the galaxies, a diffuse haze of hydrogen gas left over from the Big Bang is spread so thin there’s only one atom per cubic meter. On the largest scales, this diffuse material is arranged in a vast network of filamentary structures known as the “cosmic web,” its tangled strands spanning billions of light years and accounting for the majority of atoms in the Universe.

    Now a team of astronomers including J. Xavier Prochaska, professor of astronomy and astrophysics at UC Santa Cruz, has made the first measurements of small-scale ripples in this primeval hydrogen gas. Although the regions of cosmic web they studied lie nearly 11 billion light years away, they were able to measure variations in its structure on scales a 100,000 times smaller, comparable to the size of a single galaxy. The researchers presented their findings in a paper published April 27 in Science.

    Intergalactic gas is so tenuous that it emits no light of its own. Instead astronomers study it indirectly, by observing how it selectively absorbs the light coming from faraway sources known as quasars. Quasars constitute a brief hyper-luminous phase of the galactic life-cycle, powered by the infall of matter onto a galaxy’s central supermassive black hole. They thus act like cosmic lighthouses—bright, distant beacons that allow astronomers to study intergalactic atoms residing between the quasars location and Earth.

    Because these hyper-luminous episodes last only a tiny fraction of a galaxy’s lifetime, quasars are correspondingly rare on the sky, and are typically separated by hundreds of millions of light years from each other. In order to probe the cosmic web on much smaller scales, the astronomers exploited a fortuitous cosmic coincidence: they identified exceedingly rare pairs of quasars, right next to each other on the sky, and measured subtle differences in the absorption of intergalactic atoms measured along the two sightlines.

    “One of the biggest challenges was developing the mathematical and statistical tools to quantify the tiny differences we measure in this new kind of data,” said Alberto Rorai, a post-doctoral researcher at Cambridge university and lead author of the study. Rorai developed these tools as part of the research for his doctoral degree, and applied his tools to spectra of quasars obtained by the team on the largest telescopes in the world, including the 10-meter Keck telescopes at the W. M. Keck Observatory on Mauna Kea, Hawaii.

    The astronomers compared their measurements to supercomputer models that simulate the formation of cosmic structures from the Big Bang to the present.

    “The input to our simulations are the laws of physics and the output is an artificial universe which can be directly compared to astronomical data. I was delighted to see that these new measurements agree with the well-established paradigm for how cosmic structures form,” said Jose Oñorbe, a post-doctoral researcher at the Max Planck Institute for Astronomy, who led the supercomputer simulation effort. On a single laptop, these complex calculations would have required almost a thousand years to complete, but modern supercomputers enabled the researchers to carry them out in just a few weeks.

    “One reason why these small-scale fluctuations are so interesting is that they encode information about the temperature of gas in the cosmic web just a few billion years after the Big Bang,” said Joseph Hennawi, a professor of physics at UC Santa Barbara who led the search for quasar pairs.

    Astronomers believe that the matter in the universe went through phase transitions billions of years ago, which dramatically changed its temperature. These phase transitions, known as cosmic reionization, occurred when the collective ultraviolet glow of all stars and quasars in the universe became intense enough to strip electrons off of the atoms in intergalactic space. How and when reionization occurred is one of the biggest open questions in the field of cosmology, and these new measurements provide important clues that will help narrate this chapter of the history of the universe.

    Telescopes in this study:

    Keck Observatory, Mauna Kea, Hawaii, USA

    ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    Carnegie 6.5 meter Magellan Baade and Clay Telescopes located at Carnegie’s Las Campanas Observatory, Chile.

    See the full article here .

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    UCO Lick Shane Telescope
    UCO Lick Shane Telescope interior
    Shane Telescope at UCO Lick Observatory, UCSC

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    UC Santa Cruz campus
    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

    UCSC is the home base for the Lick Observatory.

    Lick Observatory's Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building
    Lick Observatory’s Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building

    Search for extraterrestrial intelligence expands at Lick Observatory
    New instrument scans the sky for pulses of infrared light
    March 23, 2015
    By Hilary Lebow
    1
    The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch) UCSC Lick Nickel telescope

    Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.

    “Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.

    Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.

    Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.

    5
    UCSC alumna Shelley Wright, now an assistant professor of physics at UC San Diego, discusses the dichroic filter of the NIROSETI instrument. (Photo by Laurie Hatch)

    Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.

    “The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.

    The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”

    Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.

    “We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”

    Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.

    “This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”

    NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.

    “Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”

    NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.

    The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.

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    UCSC is the home base for the Lick Observatory.

     
  • richardmitnick 8:40 am on March 30, 2017 Permalink | Reply
    Tags: , , , , Supermassive Black Holes, TXS 0828+193, TXS0211−122   

    From Keck and IAC via phys.org: “Expanding super bubble of gas detected around massive black holes in the early universe” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    2

    Instituto de Astrofísica e Ciências do Espaço

    phys.org

    1
    Left – Composite image of a large gas blob of glowing hydrogen gas, shown by a Lyman-alpha optical image (colored yellow) from the Subaru telescope (NAOJ). A galaxy located in the blob is visible in a broadband optical image (white) from the Hubble Space Telescope and an infrared image from the Spitzer Space Telescope (red). Finally, the Chandra X-ray Observatory image in blue shows evidence for a growing supermassive black hole in the center of the galaxy. Radiation and outflows from this active black hole are powerful enough to light up and heat the gas in the blob.

    In a study led by Sandy Morais, a PhD student at Instituto de Astrofísica e Ciências do Espaço and Faculty of Sciences of the University of Porto (FCUP), researchers found massive super bubbles of gas and dust around two distant radio galaxies about 11.5 billion light years away.

    Andrew Humphrey (IA & University of Porto), the leader of the project, commented: “By studying violent galaxies like these, we have gained a new insight into the way supermassive black holes affect the evolution of the galaxies in which they reside.”

    The researchers used two of the largest observatories available today, the Keck II (Hawaii) and the Gran Telescópio de Canárias (GTC), to observe TXS0211−122 and TXS 0828+193, two powerful radio galaxies, harboring the most energetic type of Active Galactic Nuclei (AGN) known. This type of galaxy houses the most massive black holes and have the most powerful continuous energy ejections known.

    The team discovered expanding super bubbles of gas around each of TXS 0211-122 and TXS 0828+193, most likely caused by “feedback” activity whereby the AGN injects vast quantities of energy into its host galaxy, creating a powerful wind that sweeps up gas and dust into an expanding super bubble.

    Study of the symbiosis between the supermassive black hole and the galaxy is a key to understanding the evolution of the most massive galaxies. Ultraviolet emission from the black hole’s accretion disk can inhibit star formation temporarily, by ionizing the Interstellar medium, and the great outflows of gas towards the black hole can lead to permanent inhibition of star formation.

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    Schematic of the expanding gas Bubble, over a radio image of the full field of TXS 0828+193. Credit: Morais et al. 2017

    More information: S. G. Morais et al. Ionization and feedback in Lyα haloes around two radio galaxies at∼ 2.5, Monthly Notices of the Royal Astronomical Society (2017). DOI: 10.1093/mnras/stw2926

    See the full article here .

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    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometer and world-leading laser guide star adaptive optics systems. Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

    Institute of Astrophysics and Space Sciences

    Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

     
    • RIcardo Reis 5:49 am on March 31, 2017 Permalink | Reply

      This research was NOT made by Instituto de Astrofisica de Canarias in Spain, but by Instituto de Astrofísica e Ciências do Espaço in Portugal.
      In fact, if you check the paper (https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stw2926), this research has no one from IAC.

      Like

    • richardmitnick 7:47 am on March 31, 2017 Permalink | Reply

      Thank you very much for the correction. I did not read far enough and got myself stuck in the acronym. I believe that I have sufficiently corrected the post. Please look at it again and let me know what you think.

      Thanks again for your help.

      Like

  • richardmitnick 12:31 pm on March 23, 2017 Permalink | Reply
    Tags: , , , , Hubble detects supermassive black hole kicked out of galactic core, , Supermassive Black Holes   

    From ESA/Hubble: “Hubble detects supermassive black hole kicked out of galactic core”and from NASA/HubbleSite “Gravitational Wave Kicks Monster Black Hole Out Of Galactic Core “ 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    From ESA/Hubble

    “Hubble detects supermassive black hole kicked out of galactic core”

    23 March 2017
    Marco Chiaberge
    Space Telescope Science Institute
    Baltimore, USA
    Tel: +1 410 338 4980
    Email: chiab@stsci.edu

    Stefano Bianchi
    Roma Tre University
    Rome, Italy
    Tel: +39 657337241
    Email: bianchi@fis.uniroma3.it

    Mathias Jäger
    ESA/Hubble, Public Information Officer
    Garching bei München, Germany
    Cell: +49 17662397500
    Email: mjaeger@partner.eso.org

    1
    The galaxy 3C186, located about 8 billion years from Earth, is most likely the result of a merger of two galaxies. This is supported by arc-shaped tidal tails, usually produced by a gravitational tug between two colliding galaxies, identified by the scientists. The merger of the galaxies also led to a merger of the two supermassive black holes in their centres, and the resultant black hole was then kicked out of its parent galaxy by the gravitational waves created by the merger. The bright, star-like looking quasar can be seen in the centre of the image. Its former host galaxy is the faint, extended object behind it. Credit: NASA, ESA, and M. Chiaberge (STScI/ESA)

    2
    An international team of astronomers using the NASA/ESA Hubble Space Telescope have uncovered a supermassive black hole that has been propelled out of the centre of the distant galaxy 3C186. The black hole was most likely ejected by the power of gravitational waves. This is the first time that astronomers found a supermassive black hole at such a large distance from its host galaxy centre.

    Though several other suspected runaway black holes have been seen elsewhere, none has so far been confirmed. Now astronomers using the NASA/ESA Hubble Space Telescope have detected a supermassive black hole, with a mass of one billion times the Sun’s, being kicked out of its parent galaxy. “We estimate that it took the equivalent energy of 100 million supernovae exploding simultaneously to jettison the black hole,” describes Stefano Bianchi, co-author of the study, from the Roma Tre University, Italy.

    The images taken by Hubble provided the first clue that the galaxy, named 3C186, was unusual. The images of the galaxy, located 8 billion light-years away, revealed a bright quasar, the energetic signature of an active black hole, located far from the galactic core. “Black holes reside in the centres of galaxies, so it’s unusual to see a quasar not in the centre,” recalls team leader Marco Chiaberge, ESA-AURA researcher at the Space Telescope Science Institute, USA.

    The team calculated that the black hole has already travelled about 35 000 light-years from the centre, which is more than the distance between the Sun and the centre of the Milky Way. And it continues its flight at a speed of 7.5 million kilometres per hour [1]. At this speed the black hole could travel from Earth to the Moon in three minutes.

    Although other scenarios to explain the observations cannot be excluded, the most plausible source of the propulsive energy is that this supermassive black hole was given a kick by gravitational waves [2] unleashed by the merger of two massive black holes at the centre of its host galaxy. This theory is supported by arc-shaped tidal tails identified by the scientists, produced by a gravitational tug between two colliding galaxies.

    According to the theory presented by the scientists, 1-2 billion years ago two galaxies — each with central, massive black holes — merged. The black holes whirled around each other at the centre of the newly-formed elliptical galaxy, creating gravitational waves that were flung out like water from a lawn sprinkler [3]. As the two black holes did not have the same mass and rotation rate, they emitted gravitational waves more strongly along one direction. When the two black holes finally merged, the anisotropic emission of gravitational waves generated a kick that shot the resulting black hole out of the galactic centre.

    “If our theory is correct, the observations provide strong evidence that supermassive black holes can actually merge,” explains Stefano Bianchi on the importance of the discovery. “There is already evidence of black hole collisions for stellar-mass black holes, but the process regulating supermassive black holes is more complex and not yet completely understood.”

    The researchers are lucky to have caught this unique event because not every black hole merger produces imbalanced gravitational waves that propel a black hole out of the galaxy. The team now wants to secure further observation time with Hubble, in combination with the Atacama Large Millimeter/submillimeter Array (ALMA) and other facilities, to more accurately measure the speed of the black hole and its surrounding gas disc, which may yield further insights into the nature of this rare object.
    Notes

    [1] As the black hole cannot be observed directly, the mass and the speed of the supermassive black holes were determined via spectroscopic analysis of its surrounding gas.

    [2] First predicted by Albert Einstein, gravitational waves are ripples in space that are created by accelerating massive objects. The ripples are similar to the concentric circles produced when a rock is thrown into a pond. In 2016, the Laser Interferometer Gravitational-wave Observatory (LIGO) helped astronomers prove that gravitational waves exist by detecting them emanating from the union of two stellar-mass black holes, which are several times more massive than the Sun.

    [3] The black holes get closer over time as they radiate away gravitational energy.

    The international team of astronomers in this study consists of Marco Chiaberge (STScI, USA; Johns Hopkins University, USA), Justin C. Ely (STScI, USA), Eileen Meyer (University of Maryland Baltimore County, USA), Markos Georganopoulos (University of Maryland Baltimore County, USA; NASA Goddard Space Flight Center, USA), Andrea Marinucci (Università degli Studi Roma Tre, Italy), Stefano Bianchi (Università degli Studi Roma Tre, Italy), Grant R. Tremblay (Yale University, USA), Brian Hilbert (STScI, USA), John Paul Kotyla (STScI, USA), Alessandro Capetti (INAF – Osservatorio Astrofisico di Torino, Italy), Stefi Baum (University of Manitoba, Canada), F. Duccio Macchetto (STScI, USA), George Miley (University of Leiden, Netherlands), Christopher O’Dea (University of Manitoba, Canada), Eric S. Perlman (Florida Institute of Technology, USA), William B. Sparks (STScI, USA) and Colin Norman (STScI, USA; Johns Hopkins University, USA)

    Image credit: NASA, ESA, M. Chiaberge (STScI/ESA)

    Science paper:
    The puzzling case of the radio-loud QSO 3C 186: a gravitational wave recoiling black hole in a young radio source?

    From NASA HubbleSite

    “Gravitational Wave Kicks Monster Black Hole Out Of Galactic Core “

    Mar 23, 2017

    Donna Weaver
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4493
    dweaver@stsci.edu

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

    Marco Chiaberge
    Space Telescope Science Institute and
    The Johns Hopkins University, Baltimore, Maryland
    410-338-4980
    marcoc@stsci.edu

    3
    Runaway black hole is the most massive ever detected far from its central home
    Normally, hefty black holes anchor the centers of galaxies. So researchers were surprised to discover a supermassive black hole speeding through the galactic suburbs. Black holes cannot be observed directly, but they are the energy source at the heart of quasars — intense, compact gushers of radiation that can outshine an entire galaxy. NASA’s Hubble Space Telescope made the discovery by finding a bright quasar located far from the center of the host galaxy.

    Researchers estimate that it took the equivalent energy of 100 million supernovas exploding simultaneously to jettison the black hole. What could pry this giant monster from its central home? The most plausible explanation for this propulsive energy is that the monster object was given a kick by gravitational waves unleashed by the merger of two black holes as a result of a collision between two galaxies. First predicted by Albert Einstein, gravitational waves are ripples in the fabric of space that are created when two massive objects collide.

    The Full [HubbleSite] Story

    Astronomers have uncovered a supermassive black hole that has been propelled out of the center of a distant galaxy by what could be the awesome power of gravitational waves.

    Though there have been several other suspected, similarly booted black holes elsewhere, none has been confirmed so far. Astronomers think this object, detected by NASA’s Hubble Space Telescope, is a very strong case. Weighing more than 1 billion suns, the rogue black hole is the most massive black hole ever detected to have been kicked out of its central home.

    Researchers estimate that it took the equivalent energy of 100 million supernovas exploding simultaneously to jettison the black hole. The most plausible explanation for this propulsive energy is that the monster object was given a kick by gravitational waves unleashed by the merger of two hefty black holes at the center of the host galaxy.

    First predicted by Albert Einstein, gravitational waves are ripples in space that are created when two massive objects collide. The ripples are similar to the concentric circles produced when a hefty rock is thrown into a pond. Last year, the Laser Interferometer Gravitational-Wave Observatory (LIGO) helped astronomers prove that gravitational waves exist by detecting them emanating from the union of two stellar-mass black holes, which are several times more massive than the sun.

    Hubble’s observations of the wayward black hole surprised the research team. “When I first saw this, I thought we were seeing something very peculiar,” said team leader Marco Chiaberge of the Space Telescope Science Institute (STScI) and Johns Hopkins University, in Baltimore, Maryland. “When we combined observations from Hubble, the Chandra X-ray Observatory, and the Sloan Digital Sky Survey, it all pointed towards the same scenario. The amount of data we collected, from X-rays to ultraviolet to near-infrared light, is definitely larger than for any of the other candidate rogue black holes.”

    Chiaberge’s paper will appear in the March 30 issue of Astronomy & Astrophysics.

    Hubble images taken in visible and near-infrared light provided the first clue that the galaxy was unusual. The images revealed a bright quasar, the energetic signature of a black hole, residing far from the galactic core. Black holes cannot be observed directly, but they are the energy source at the heart of quasars – intense, compact gushers of radiation that can outshine an entire galaxy. The quasar, named 3C 186, and its host galaxy reside 8 billion light-years away in a galaxy cluster. The team discovered the galaxy’s peculiar features while conducting a Hubble survey of distant galaxies unleashing powerful blasts of radiation in the throes of galaxy mergers.

    “I was anticipating seeing a lot of merging galaxies, and I was expecting to see messy host galaxies around the quasars, but I wasn’t really expecting to see a quasar that was clearly offset from the core of a regularly shaped galaxy,” Chiaberge recalled. “Black holes reside in the center of galaxies, so it’s unusual to see a quasar not in the center.”

    The team calculated the black hole’s distance from the core by comparing the distribution of starlight in the host galaxy with that of a normal elliptical galaxy from a computer model. The black hole had traveled more than 35,000 light-years from the center, which is more than the distance between the sun and the center of the Milky Way.

    Based on spectroscopic observations taken by Hubble and the Sloan survey, the researchers estimated the black hole’s mass and measured the speed of gas trapped near the behemoth object. Spectroscopy divides light into its component colors, which can be used to measure velocities in space. “To our surprise, we discovered that the gas around the black hole was flying away from the galaxy’s center at 4.7 million miles an hour,” said team member Justin Ely of STScI. This measurement is also a gauge of the black hole’s velocity, because the gas is gravitationally locked to the monster object.

    The astronomers calculated that the black hole is moving so fast it would travel from Earth to the moon in three minutes. That’s fast enough for the black hole to escape the galaxy in 20 million years and roam through the universe forever.

    The Hubble image revealed an interesting clue that helped explain the black hole’s wayward location. The host galaxy has faint arc-shaped features called tidal tails, produced by a gravitational tug between two colliding galaxies. This evidence suggests a possible union between the 3C 186 system and another galaxy, each with central, massive black holes that may have eventually merged.

    Based on this visible evidence, along with theoretical work, the researchers developed a scenario to describe how the behemoth black hole could be expelled from its central home. According to their theory, two galaxies merge, and their black holes settle into the center of the newly formed elliptical galaxy. As the black holes whirl around each other, gravity waves are flung out like water from a lawn sprinkler. The hefty objects move closer to each other over time as they radiate away gravitational energy. If the two black holes do not have the same mass and rotation rate, they emit gravitational waves more strongly along one direction. When the two black holes collide, they stop producing gravitational waves. The newly merged black hole then recoils in the opposite direction of the strongest gravitational waves and shoots off like a rocket.

    The researchers are lucky to have caught this unique event because not every black-hole merger produces imbalanced gravitational waves that propel a black hole in the opposite direction. “This asymmetry depends on properties such as the mass and the relative orientation of the back holes’ rotation axes before the merger,” said team member Colin Norman of STScI and Johns Hopkins University. “That’s why these objects are so rare.”

    An alternative explanation for the offset quasar, although unlikely, proposes that the bright object does not reside within the galaxy. Instead, the quasar is located behind the galaxy, but the Hubble image gives the illusion that it is at the same distance as the galaxy. If this were the case, the researchers should have detected a galaxy in the background hosting the quasar.

    If the researchers’ interpretation is correct, the observations may provide strong evidence that supermassive black holes can actually merge. Astronomers have evidence of black-hole collisions for stellar-mass black holes, but the process regulating supermassive black holes is more complex and not completely understood.

    The team hopes to use Hubble again, in combination with the Atacama Large Millimeter/submillimeter Array (ALMA) and other facilities, to more accurately measure the speed of the black hole and its gas disk, which may yield more insight into the nature of this bizarre object.

    See the full ESA article here .

    See the full NASA HubbleSite story here .

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

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  • richardmitnick 8:38 am on March 19, 2017 Permalink | Reply
    Tags: , , , , , Supermassive Black Holes, TDE's, When galaxies collide black holes eat   

    From EarthSky: “When galaxies collide, black holes eat” 

    1

    EarthSky

    March 12, 2017
    Deborah Byrd

    When our Milky Way galaxy and neighboring Andromeda galaxy collide, supermassive black holes will have a feast!

    1
    Artist’s concept of a Tidal Disruption Event, in which a black hole eats a star, in the distant galaxy F01004-2237. As the black hole swallows the star, there’s a release of gravitational energy from the star’s debris. The result is a visible flare. Image via Mark Garlick.

    What’ll our sky look like 5 billion years from now, when our Milky Way galaxy merges with the nearby Andromeda galaxy? If there are any people left to look then [this is false, there will be no people, as our sun will hve in 3 billion years grown into a red giant, consumed Mercury and Venue, and at least fried Earth before eating it] they’ll be able to see flares about every 10 to 100 years, each time our Milky Way’s central supermassive black hole swallows a star. The flares will be visible to the unaided eye [forget it, but still you need to pay your taxes]. They’ll appear much brighter than any other star or planet in the night sky. That’s according to astronomers at the University of Sheffield in England, who say that central, supermassive black holes in colliding galaxies swallow stars some 100 times more often than previously thought.

    Their study was published March 1, 2017 in the peer-reviewed journal Nature Astronomy.

    The study is based on a survey of just 15 galaxies, a very small sample size by astronomical standards. However, in that small sample, the astronomers were surprised to see a black hole swallow a star. Astronomers call this sort of event a tidal distruption event, or TDE. They’d been only been only seen before in surveys of many thousands of galaxies, leading astronomers to believe they were exceptionally rare: only one event every 10,000 to 100,000 years per galaxy.

    2
    Artist’s concept of Earth’s night sky in 3.75 billion years. The Andromeda galaxy (left) will fill our field of view then, astronomers say, as it heads toward a collision, or merger, with our Milky way galaxy. Image via NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger.

    The 15 galaxies of the University of Sheffield study are doing something those other thousands of galaxies weren’t doing. They’re undergoing collisions with neighboring galaxies. Study co-author James Mullaney said in a statement:

    “Our surprising findings show that the rate of TDEs dramatically increases when galaxies collide. This is likely due to the fact that the collisions lead to large numbers of stars being formed close to the central supermassive black holes in the two galaxies as they merge together.”

    Another study co-author, Rob Spence, said:

    “Our team first observed the 15 colliding galaxies in the sample in 2005, during a previous project.

    However, when we observed the sample again in 2015, we noticed that one galaxy – F01004-2237 – appeared strikingly different. This led us to look at data from the Catalina Sky Survey, which monitors the brightness of objects in the sky over time. We found that in 2010, the brightness of F01004-2237 flared dramatically.”

    Galaxy F01004-2237 – which is 1.7 billion light years from Earth – had flared in a way characteristic of TDEs. These events are known to cause flaring due to energy release, as a star edges toward a galaxy’s central, supermassive black hole.

    3
    NGC 2207 and IC 2163 are two spiral galaxies in the process of merging, or colliding. If the new study from University of Sheffield is correct, there is a much greater chance for stars to be eaten in these galaxies by their central, supermassive black holes.

    Bottom line: A study from the University of Sheffield shows that collisions – like that predicted for our Milky Way galaxy and neighboring Andromeda galaxy – cause black holes to eat stars some 100 times faster than previously thought.

    See the full article here .

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  • richardmitnick 2:09 pm on March 13, 2017 Permalink | Reply
    Tags: , , , , , Supermassive Black Holes   

    From Columbia: “New Study Finds Radiation from Nearby Galaxies Helped Fuel First Monster Black Holes” 

    Columbia U bloc

    Columbia University

    March 13, 2017
    Kim Martineau

    1
    The massive black hole shown at left in this drawing is able to rapidly grow as intense radiation from a galaxy nearby shuts down star-formation in its host galaxy. Illustration Courtesy of John Wise, Georgia Tech

    The appearance of supermassive black holes at the dawn of the universe has puzzled astronomers since their discovery more than a decade ago. A supermassive black hole is thought to form over billions of years, but more than two dozen of these behemoths have been sighted within 800 million years of the Big Bang 13.8 billion years ago.

    In a new study in the journal Nature Astronomy, a team of researchers from Dublin City University, Columbia University, Georgia Tech, and the University of Helsinki, add evidence to one theory of how these ancient black holes, about a billion times heavier than our sun, may have formed and quickly put on weight.

    In computer simulations, the researchers show that a black hole can rapidly grow at the center of its host galaxy if a nearby galaxy emits enough radiation to switch off its capacity to form stars. Thus disabled, the host galaxy grows until its eventual collapse, forming a black hole that feeds on the remaining gas, and later, dust, dying stars, and possibly other black holes, to become super gigantic.

    “The collapse of the galaxy and the formation of a million-solar-mass black hole takes 100,000 years — a blip in cosmic time,” says study co-author Zoltan Haiman, an astronomy professor at Columbia University. “A few hundred-million years later, it has grown into a billion-solar-mass supermassive black hole. This is much faster than we expected.”

    In the early universe, stars and galaxies formed as molecular hydrogen cooled and deflated a primordial plasma of hydrogen and helium. This environment would have limited black holes from growing very big as molecular hydrogen turned gas into stars far enough away to escape the black holes’ gravitational pull. Astronomers have come up with several ways that supermassive black holes might have overcome this barrier.

    In a 2008 study, Haiman and his colleagues hypothesized that radiation from a massive neighboring galaxy could split molecular hydrogen into atomic hydrogen and cause the nascent black hole and its host galaxy to collapse rather than spawn new clusters of stars.

    A later study led by Eli Visbal, then a postdoctoral researcher at Columbia, calculated that the nearby galaxy would have to be at least 100 million times more massive than our sun to emit enough radiation to stop star-formation. Though relatively rare, enough galaxies of this size exist in the early universe to explain the supermassive black holes observed so far.

    The current study, led by John Regan, a postdoctoral researcher at Ireland’s Dublin City University, modeled the process using software developed by Columbia’s Greg Bryan, and includes the effects of gravity, fluid dynamics, chemistry and radiation.

    After several days of crunching the numbers on a supercomputer, the researchers found that the neighboring galaxy could be smaller and closer than previously estimated. “The nearby galaxy can’t be too close, or too far away, and like the Goldilocks principle, too hot or too cold,” said study coauthor John Wise, an associate astrophysics professor at Georgia Tech.

    Though massive black holes are found at the center of most galaxies in the mature universe, including our own Milky Way, they are far less common in the infant universe. The earliest supermassive black holes were first sighted in 2001 through a telescope at New Mexico’s Apache Point Observatory as part of the Sloan Digital Sky Survey.


    SDSS Telescope at Apache Point Observatory, NM, USA

    The researchers hope to test their theory when NASA’s James Webb Space Telescope, the successor to Hubble, goes online next year and beams back images from the early universe.

    Other models of how supermassive black holes evolved, including one in which black holes grow by merging with millions of smaller black holes and stars, await further testing. “Understanding how supermassive black holes form tells us how galaxies, including our own, form and evolve, and ultimately, tells us more about the universe in which we live,” said Regan, at Dublin City University.

    See the full article here .

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    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
  • richardmitnick 2:11 pm on March 9, 2017 Permalink | Reply
    Tags: , , , Hubble Dates Black Hole’s Last Big Meal, , , Supermassive Black Holes   

    From Hubble: “Hubble Dates Black Hole’s Last Big Meal” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    Mar 9, 2017

    Felicia Chou
    NASA Headquarters, Washington, D.C.
    felicia.chou@nasa.gov
    202-358-0257

    Donna Weaver / Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4493 / 410-338-4514
    dweaver@stsci.edu / villard@stsci.edu

    Rongmon Bordoloi
    Massachusetts Institute of Technology, Cambridge, Massachusetts
    617-252-1736
    bordoloi@mit.edu

    1
    Illustration Credit: NASA, ESA, and Z. Levy (STScI)

    For the supermassive black hole at the center of our Milky Way galaxy [Sag A*], it’s been a long time between dinners.


    Sag A* NASA Chandra X-Ray Observatory 23 July 2014, the supermassive black hole at the center of the Milky Way

    NASA’s Hubble Space Telescope has found that the black hole ate its last big meal about 6 million years ago, when it consumed a large clump of infalling gas. After the meal, the engorged black hole burped out a colossal bubble of gas weighing the equivalent of millions of suns, which now billows above and below our galaxy’s center.

    The immense structures, dubbed the Fermi Bubbles, were first discovered in 2010 by NASA’s Fermi Gamma-ray Space Telescope.


    NASA’s Fermi Gamma-ray Space Telescope

    But recent Hubble observations of the northern bubble have helped astronomers determine a more accurate age for the bubbles and how they came to be.

    “For the first time, we have traced the motion of cool gas throughout one of the bubbles, which allowed us to map the velocity of the gas and calculate when the bubbles formed,” said lead researcher Rongmon Bordoloi of the Massachusetts Institute of Technology in Cambridge. “What we find is that a very strong, energetic event happened 6 million to 9 million years ago. It may have been a cloud of gas flowing into the black hole, which fired off jets of matter, forming the twin lobes of hot gas seen in X-ray and gamma-ray observations. Ever since then, the black hole has just been eating snacks.”

    The new study is a follow-on to previous Hubble observations that placed the age of the bubbles at 2 million years old.

    A black hole is a dense, compact region of space with a gravitational field so intense that neither matter nor light can escape. The supermassive black hole at the center of our galaxy has compressed the mass of 4.5 million sun-like stars into a very small region of space.

    Material that gets too close to a black hole is caught in its powerful gravity and swirls around the compact powerhouse until it eventually falls in. Some of the matter, however, gets so hot it escapes along the black hole’s spin axis, creating an outflow that extends far above and below the plane of a galaxy.

    The team’s conclusions are based on observations by Hubble’s Cosmic Origins Spectrograph (COS), which analyzed ultraviolet light from 47 distant quasars. Quasars are bright cores of distant active galaxies.


    NASA Hubble Cosmic Origins Spectrograph

    Imprinted on the quasars’ light as it passes through the Milky Way bubble is information about the speed, composition, and temperature of the gas inside the expanding bubble.

    The COS observations measured the temperature of the gas in the bubble at approximately 17,700 degrees Fahrenheit. Even at those sizzling temperatures, this gas is much cooler than most of the super-hot gas in the outflow, which is 18 million degrees Fahrenheit, seen in gamma rays. The cooler gas seen by COS could be interstellar gas from our galaxy’s disk that is being swept up and entrained into the super-hot outflow. COS also identified silicon and carbon as two of the elements being swept up in the gaseous cloud. These common elements are found in most galaxies and represent the fossil remnants of stellar evolution.

    The cool gas is racing through the bubble at 2 million miles per hour. By mapping the motion of the gas throughout the structure, the astronomers estimated that the minimum mass of the entrained cool gas in both bubbles is equivalent to 2 million suns. The edge of the northern bubble extends 23,000 light-years above the galaxy.

    “We have traced the outflows of other galaxies, but we have never been able to actually map the motion of the gas,” Bordoloi said. “The only reason we could do it here is because we are inside the Milky Way. This vantage point gives us a front-row seat to map out the kinematic structure of the Milky Way outflow.”

    The new COS observations build and expand on the findings of a 2015 Hubble study by the same team, in which astronomers analyzed the light from one quasar that pierced the base of the bubble.

    “The Hubble data open a whole new window on the Fermi Bubbles,” said study co-author Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland. “Before, we knew how big they were and how much radiation they emitted; now we know how fast they are moving and which chemical elements they contain. That’s an important step forward.”

    The Hubble study also provides an independent verification of the bubbles and their origin, as detected by X-ray and gamma-ray observations.

    “This observation would be almost impossible to do from the ground because you need ultraviolet spectroscopy to detect the fingerprints of these elements, which can only be done from space,” Bordoloi said. “Only with COS do you have the wavelength coverage, the sensitivity, and the spectral resolution coverage to make this observation.”

    The Hubble results appeared in the January 10, 2017, edition of The Astrophysical Journal.

    See the full article here .

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

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  • richardmitnick 10:02 pm on March 3, 2017 Permalink | Reply
    Tags: , , , , , IRAS 13224−3809, , Supermassive Black Holes   

    From Astronomy: “This nearby supermassive black hole packs a pretty big punch” 

    Astronomy magazine

    Astronomy Magazine

    March 01, 2017
    Alison Klesman

    1
    NGC 6814 is a stunning example of a Seyfert galaxy. Like IRAS 13224−3809, this galaxy hosts a bright, highly X-ray variable supermassive black hole at its center. ESA/Hubble & NASA; Acknowledgement: Judy Schmidt (Geckzilla)

    Supermassive black holes are associated with the vast majority of galaxies. They’re believed to evolve with their host galaxies and even to affect galaxy growth over time, owing to their ability to gobble up vast amounts of gas and dust and shoot high-energy radiation back out into their surroundings.

    There are measurable correlations between the mass of a supermassive black hole and the properties of its host galaxy’s bulge, such as the luminosity of the bulge and the movements of stars within it. The reasons for these correlations are still unknown, but astronomers have long believed that supermassive black holes affect the star formation around them via some sort of feedback process.

    In a letter printed today in Nature, a group of astronomers led by Michael Parker at the Institute of Astronomy in Cambridge, UK, report their observations of IRAS 13224−3809, a nearby Seyfert galaxy hosting an active galactic nucleus, or AGN. Seyfert galaxies shine intensely in infrared light due to the activity of their supermassive black holes, which are relatively low mass but are accreting at high rates. IRAS 13224−3809 hosts a central supermassive black hole weighing about 6,000,000 times the mass of our Sun.

    Parker and his coauthors studied observations of IRAS 13224−3809 taken with the X-ray Multi-Mirror Mission [ESA/XMM-Newton] over the course of 17 days and with the Nuclear Spectroscopic Telescope Array [NASA/NuSTAR] over the course of six days. They observed X-ray variability on scales of minutes to weeks.

    ESA/XMM Newton
    ESA/XMM Newton

    NASA/NuSTAR
    NASA/NuSTAR

    By looking at the X-ray spectrum of the source, they were able to determine that this object offers a relatively unhindered view right down into the inner portions of the accretion disk near the black hole itself.

    When astronomers “look” at a supermassive black hole, they’re actually observing light from the accretion disk of matter around the black hole, which hasn’t yet fallen past the event horizon and become invisible. Supermassive black holes show variability over time in a variety of wavelengths, including optical light, infrared light, and X-rays. This variability is believed to arise from changes in the accretion disk, such as clumps of matter or outflows of gas and radiation.

    IRAS 13224−3809’s black hole shows extraordinary X-ray variability — in fact, it’s the most variable AGN observed at X-ray wavelengths. Parker’s group was able to watch the effects of an ultrafast outflow, which is associated with areas of the accretion disk within a few hundred times the size of the event horizon. Ultrafast outflows, or UFOs, are outflows moving faster than about 6,000 miles per second (10,000 km/s). They’re believed to be triggered by X-ray radiation associated with accretion at the innermost portions of the disk, just a few times the size of the event horizon.

    IRAS 13224−3809’s outflow was clocked at 44,000 miles per second (71,000 km/s), or about 0.236 times the speed of light. This puts it in the top 5 percent of UFOs ever observed. What’s more, the power it’s putting out is on par with quasars that are three orders of magnitude more massive.

    Because of their immense power, IRAS 13224−3809’s outflows may be strong enough to drive feedback in its host galaxy, just as more massive quasars do in the much more distant universe.

    While all black holes are variable, the timescale of variability typically scales with size. This makes sense when you think of variability relating to the accretion disk, which also scales with size. Thus, IRAS 13224−3809 shows much faster variability than the variability observed in quasars, which are similar but much more massive objects. Parker and his group were able to watch IRAS 13224−3809’s X-ray light undergo changes that took only hours, rather than months in a quasar.

    Studying IRAS 13224−3809 could thus help astronomers finally start to answer questions about how UFOs and other outflows are created. It could also shed light on how black hole feedback affects the host galaxy. This object’s unique properties would allow studies to be performed more easily and with much shorter observing times than those focused on faraway, slower-acting quasars.

    See the full article here .

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  • richardmitnick 3:13 pm on February 27, 2017 Permalink | Reply
    Tags: , , , Supermassive Black Holes, Tidal Distruption Events, U Sheffield   

    From Sheffield: “Stars regularly ripped apart by black holes in colliding galaxies” 

    u-sheffield-bloc

    University of Sheffield

    27 February 2017

    1
    Depiction of the tidal disruption event in F01004-2237. The release of gravitational energy as the debris of the star is accreted by the black hole leads to a flare in the optical light of the galaxy. Credit and copyright: Mark Garlick.

    2
    A black hole devouring a star. Credit: NASA (phys.org)

    Astronomers based at the University of Sheffield have found evidence that stars are ripped apart by supermassive black holes 100 times more often than previously thought.

    Until now, such stellar cannibalism – known as Tidal Distruption Events, or TDEs – had only been found in surveys which observed many thousands of galaxies, leading astronomers to believe they were exceptionally rare: only one event every 10,000 to 100,000 years per galaxy.

    However, the pioneering study conducted by leading scientists from the University’s Department of Physics and Astronomy, recorded a star being destroyed by a supermassive black hole in a survey of just 15 galaxies – an extremely small sample size by astronomy standards.

    “Each of these 15 galaxies is undergoing a ‘cosmic collision’ with a neighbouring galaxy,” said Dr James Mullaney, Lecturer in Astronomy and co-author of the study.

    “Our surprising findings show that the rate of TDEs dramatically increases when galaxies collide. This is likely due to the fact that the collisions lead to large numbers of stars being formed close to the central supermassive black holes in the two galaxies as they merge together.”

    The supermassive black holes that lurk in the hearts of all large galaxies can be elusive. This is because they don’t shine in a conventional sense due to their gravity being so strong that nothing can escape, not even light itself. However, the release of energy as stars are ripped apart when they move close to the black holes leads to dramatic flares. The galaxies’ nuclei can then appear as bright as all the billions of stars in a typical galaxy combined. In this way, TDEs can be used to locate otherwise dim black holes and study their strong gravity and how they accrete matter.

    “Our team first observed the 15 colliding galaxies in the sample in 2005, during a previous project,” said Rob Spence, University of Sheffield PhD student and co-author of the study.

    “However, when we observed the sample again in 2015, we noticed that one galaxy – F01004-2237 – appeared strikingly different. This led us to look at data from the Catalina Sky Survey, which monitors the brightness of objects in the sky over time. We found that in 2010, the brightness of F01004-2237 flared dramatically.”

    The particular combination of variability and post-flare spectrum observed in F01004-2237 – which is 1.7 billion light years from Earth – was unlike any known supernova or active galactic nucleus, but characteristic of TDEs.

    Clive Tadhunter, Professor of Astrophysics and leader of the study, said: “Based on our results for F01004-2237, we expect that TDE events will become common in our own Milky Way galaxy when it eventually merges with the neighbouring Andromeda galaxy in about 5 billion years.

    “Looking towards the centre of the Milky Way at the time of the merger we’d see a flare approximately every 10 to 100 years. The flares would be visible to the naked eye and appear much brighter than any other star or planet in the night sky.”

    The study, published today (27 February 2017) in the journal Nature: Astronomy, was supported by a grant from the UK Science and Technology Facilities Council.

    The findings were based on observations made with the William Herschel Telescope, which is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canaria. The study also used data taken with NASA/ESA Hubble Space Telescope, and the Catalina Sky Survey.

    ING 4 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands
    ING 4 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    Scientists at the University of Sheffield’s Department of Physics and Astronomy are exploring the fundamental laws of the universe and developing pioneering technologies.

    Students in the Department work with leading academics in the field to look beyond our planet to tackle global challenges – from climate change to meeting energy demands. This research further cements the University’s position at the forefront of Physics and Astronomy research.

    See the full article here .

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    u-sheffield-campus

    The University of Sheffield (informally Sheffield University is a public research university in Sheffield, South Yorkshire, England. It received its royal charter in 1905 as successor to the University College of Sheffield, which was established in 1897 by the merger of Sheffield Medical School (founded in 1828), Firth College (1879) and Sheffield Technical School (1884).

    Sheffield is a multi-campus university predominantly over two campus areas: the Western Bank and the St George’s. The university is organised into five academic faculties composed of multiple departments. It had 19,555 undergraduate and 8,370 postgraduate students in 2015/16 and its total and research income came to £635.7 million and £168.5 million in 2015/16 respectively, which made Sheffield among the top 10 of the UK universities in terms of Net assets.

    Sheffield was placed 84th worldwide by The QS World University Rankings 2016. In 2011, Sheffield was named ‘University of the Year’ in the Times Higher Education awards. The Times Higher Education Student Experience Survey 2014 ranked the University of Sheffield 1st for student experience, social life, university facilities and accommodation, among other categories.

    It is one of the original red brick universities, a member of the Russell Group of research-intensive universities, the Worldwide Universities Network, the N8 Group of the eight most research intensive universities in Northern England and the White Rose University Consortium. There are seven Nobel Prize laureates amongst Sheffield academics, six of which are its alumni or former staff.

     
  • richardmitnick 1:20 pm on February 5, 2017 Permalink | Reply
    Tags: , , , , Maarten Schmidt, , quasi-stellar radio source 3C273, Supermassive Black Holes   

    From EarthSky: “Today in science: Quasar mystery solved” A Fascinating Look Back to February 5, 1963 

    1

    EarthSky

    February 5, 2017
    Deborah Byrd

    1
    Maarten Schmidt via CalTech

    February 5, 1963. On this date, Caltech astronomer Maarten Schmidt solved a puzzle about the quasi-stellar radio source 3C273 that changed the way we think about our universe.

    1
    X-ray image of 3C273 and its jet. Today, this quasar is known to lie at the center of a giant elliptical galaxy. Image via Chandra X-ray Observatory.

    This object appeared starlike, like a point of light, with a mysterious jet. But its spectrum – the range of wavelengths of its light – looked odd. Astronomers routinely use spectra to learn the composition of distant objects. But, in 1963, emission lines in the spectrum of 3C273 didn’t appear to match any known chemical elements. Schmidt had a sudden realization that 3C273 contained the very ordinary element hydrogen. He realized that the spectral lines of hydrogen appeared strange because they were highly shifted toward the red end of the spectrum. Such a large red shift could occur if 3C273 were very distant, about three billion light-years away.

    Dr. Schmidt told EarthSky that he recognized immediately the implications of his revelation. He said:

    “This realization came immediately: my wife still remembers that I was pacing up and down much of the evening”

    The implications were just this. To be so far away and still visible, 3C273 must be intrinsically very bright and very powerful. It’s now thought to shine with the light of two trillion stars like our sun. That’s hundreds of times the light of our entire Milky Way galaxy. Yet 3C273 appears to be less than a light-year across, in contrast to 100,000 light-years for our Milky Way.

    So 3C273 is not only distant. It is also exceedingly luminous, implying powerful energy-producing processes unknown in 1963. Schmidt announced his revelation about quasars in the journal Nature on March 16, 1963.

    Today, hundreds of thousands of quasars are known, and many are more distant and more powerful than 3C273. It’s no exaggeration to say they turned the science of astronomy on its ear. Why, for example, are these powerful quasars located so far away in space? Because light travels at a finite speed (186,000 miles per second), we are seeing distant objects in space in the distant past. In other words, quasars existed in early universe. They do not exist in our time. Why?

    In the 1960s, 3C273 and other quasars like it were strong evidence against the Fred Hoyle’s Steady State theory, which suggested that matter is continuously being created as the universe expands, leading to a universe that is the same everywhere. The quasars showed the universe is not the same everywhere and thus helped usher in Big Bang cosmology.

    2
    Timeline of the universe. A representation of the evolution of the universe over 13.77 billion years. The far left depicts the earliest moment we can now probe, when a period of “inflation” produced a burst of exponential growth in the universe. (Size is depicted by the vertical extent of the grid in this graphic.) For the next several billion years, the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity. More recently, the expansion has begun to speed up again as the repulsive effects of dark energy have come to dominate the expansion of the universe. The afterglow light seen by WMAP was emitted about 375,000 years after inflation and has traversed the universe largely unimpeded since then. The conditions of earlier times are imprinted on this light; it also forms a backlight for later developments of the universe.
    Date circa 2006
    Author NASA/WMAP Science Team

    ESA/Planck supercedes WMAP
    3
    21 March 2013
    ESA’s Planck satellite has delivered its first all-sky image of the Cosmic Microwave Background (CMB), bringing with it new challenges about our understanding of the origin and evolution of the cosmos. The image has provided the most precise picture of the early Universe so far.

    But Steady State theory had been losing ground, even before 1963. The biggest change caused by Maarten Schmidt’s revelation about the quasar 3C273 was in the way we think about our universe.

    In other words, the idea that 3C273 was extremely luminous, and yet occupied such a relatively small space, suggested powerful energies that astronomers had not contemplated before. 3C273 gave astronomers one of their first hints that we live in a universe of colossal explosive events – and extreme temperatures and luminosities – a place where mysterious black holes abound and play a major role.

    According to a March 2013 email from Caltech:

    In 1963, Schmidt’s discovery gave us an unprecedented look at how the universe behaved at a much younger period in its history – billions of years before the birth of the sun and its planets. Later, Schmidt, along with his colleague Donald Lynden-Bell, discovered that quasars are galaxies harboring supermassive black holes billions of light-years away – not stars in our own galaxy, as was once believed. His seminal work dramatically increased the scale of the observable universe and advanced our present view on the violent nature of the universe in which massive black holes play a dominant role.

    What are quasars? Astronomers today believe that a quasar is a compact region in the center of a galaxy in the early universe. The compact region is thought to surround a central supermassive black hole, much like the black hole thought to reside in the center of our own Milky Way galaxy and many (or most) other galaxies. The powerful luminosity of a quasar is thought to be the result of processes taking place in an accretion disk, or disk of material surrounding the black hole, as these supermassive black holes consume stars that pass too near.

    4
    ULAS J1120+0641, farthest quasar known as of 2011. The quasar appears as a faint red dot close to the center. Composite image created from the Sloan Digital Sky Survey and the UKIRT Infrared Deep Sky Survey, via Wikimedia Commons.

    SDSS Telescope at Apache Point Observatory, NM, USA
    SDSS Telescope at Apache Point Observatory, NM, USA

    UKIRT, located on Mauna Kea, Hawaii, USA as part of Mauna Kea Observatory
    UKIRT interior
    UKIRT, located on Mauna Kea, Hawaii, USA as part of Mauna Kea Observatory

    The Chinese-born U.S. astrophysicist Hong-Yee Chiu coined the name quasar in May 1964, in the publication Physics Today. He wrote:

    So far, the clumsily long name ‘quasi-stellar radio sources’ is used to describe these objects. Because the nature of these objects is entirely unknown, it is hard to prepare a short, appropriate nomenclature for them so that their essential properties are obvious from their name. For convenience, the abbreviated form ‘quasar’ will be used throughout this paper.

    Today, the farthest known quasar is ULAS J1120+0641. Its co-moving distance is 28.85 billion light-years.

    Bottom line: On February 5 1963, astronomer Maarten Schmidt’s flash of inspiration led to the understanding that quasi-stellar radio sources, or quasars, exist in the very distant universe. Quasars became the most distant, and most luminous, objects known. They changed the way we think about the universe.

    See the full article here .

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