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  • richardmitnick 12:39 pm on August 11, 2015 Permalink | Reply
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    From Chandra: “RGG 118: Oxymoronic Black Hole Provides Clues to Growth” 

    NASA Chandra

    August 11, 2015

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    Credit X-ray: NASA/CXC/Univ of Michigan/V.F.Baldassare, et al; Optical: SDSS
    Release Date August 11, 2015

    Astronomers have identified the smallest supermassive black hole found in the center of a galaxy.

    The mass of the black hole is about 50,000 times that of the Sun, using data from the 6.5-meter Clay Telescope.

    X-rays from hot gas swirling towards the black hole were detected by Chandra.

    The black hole may help us understand the formation of much larger supermassive black holes.

    Astronomers using NASA’s Chandra X-ray Observatory and the 6.5-meter Clay Telescope in Chile have identified the smallest supermassive black hole ever detected in the center of a galaxy, as described in our latest press release. This oxymoronic object could provide clues to how much larger black holes formed along with their host galaxies 13 billion years or more in the past.

    Astronomers estimate this supermassive black hole is about 50,000 times the mass of the Sun. This is less than half the previous lowest mass for a black hole at the center of a galaxy.

    The tiny heavyweight black hole is located in the center of a dwarf disk galaxy, called RGG 118, about 340 million light years from Earth. Our graphic shows a Sloan Digital Sky Survey [SDSS] image of RGG 118 and the inset shows a Chandra image of the galaxy’s center.

    SDSS Telescope
    SDSS at Apache Point, NM, USA

    The X-ray point source is produced by hot gas swirling around the black hole.

    Researchers estimated the mass of the black hole by studying the motion of cool gas near the center of the galaxy using visible light data from the Clay Telescope. They used the Chandra data to figure out the brightness in X-rays of hot gas swirling toward the black hole. They found that the outward push of radiation pressure of this hot gas is about 1% of the black hole’s inward pull of gravity, matching the properties of other supermassive black holes.

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    Clay Telescope

    Previously, a relationship has been noted between the mass of supermassive black holes and the range of velocities of stars in the center of their host galaxy. This relationship also holds for RGG 118 and its black hole.

    The black hole in RGG 118 is nearly 100 times less massive than the supermassive black hole found in the center of the Milky Way. It is also about 200,000 times less massive than the heaviest black holes found in the centers of other galaxies.

    Astronomers are trying to understand the formation of billion-solar-mass black holes that have been detected from less than a billion years after the Big Bang. The black hole in RGG 118 gives astronomers an opportunity to study a nearby small supermassive black hole in lieu of the first generation of black holes that are undetectable with current technology.

    Astronomers think that supermassive black holes may form when a large cloud of gas, weighing about 10,000 to 100,000 times that of the Sun, collapses into a black hole. Many of these black hole seeds then merge to form much larger supermassive black holes. Alternately, a supermassive black hole seed could come from a giant star, about 100 times the Sun’s mass, that ultimately forms into a black hole after it runs out of fuel and collapses.

    Researchers will continue to look for other supermassive black holes that are comparable in size or even smaller than the one in RGG 118 to help choose between the two options mentioned above and refine their understanding of how these objects grow.

    A preprint of these results is available online. The other co-author of the paper is Jenny Greene, from Princeton University in Princeton, New Jersey. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

    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 2:31 pm on July 9, 2015 Permalink | Reply
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    From JPL: “Distant Black Hole Wave Twists Like Giant Whip” 

    JPL

    July 9, 2015
    Whitney Clavin
    Jet Propulsion Laboratory, Pasadena, California
    818-354-4673
    whitney.clavin@jpl.nasa.gov

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    This cartoon shows how magnetic waves, called Alfvén S-waves, propagate outward from the base of black hole jets. The jet is a flow of charged particles, called a plasma, which is launched by a black hole. The jet has a helical magnetic field (yellow coil) permeating the plasma. The waves then travel along the jet, in the direction of the plasma flow, but at a velocity determined by both the jet’s magnetic properties and the plasma flow speed. The BL Lac jet examined in a new study is several light-years long, and the wave speed is about 98 percent the speed of light.

    Fast-moving magnetic waves emanating from a distant supermassive black hole undulate like a whip whose handle is being shaken by a giant hand, according to a study using data from the National Radio Astronomy Observatory’s Very Long Baseline Array. Scientists used this instrument to explore the galaxy/black hole system known as BL Lacertae (BL Lac) in high resolution.

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    This artist’s [famous and iconic]concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. (Smaller black holes also exist throughout galaxies.) In this illustration, the supermassive black hole at the center is surrounded by matter flowing onto the black hole in what is termed an accretion disk. This disk forms as the dust and gas in the galaxy falls onto the hole, attracted by its gravity.

    Also shown is an outflowing jet of energetic particles, believed to be powered by the black hole’s spin. The regions near black holes contain compact sources of high energy X-ray radiation thought, in some scenarios, to originate from the base of these jets. This high energy X-radiation lights up the disk, which reflects it, making the disk a source of X-rays. The reflected light enables astronomers to see how fast matter is swirling in the inner region of the disk, and ultimately to measure the black hole’s spin rate.

    For more information, visit http://www.nasa.gov/nustar and http://www.nustar.caltech.edu/.

    Fast Facts:

    › Black hole jets set magnetic waves in motion like whips being jerked from side to side.

    › The findings help researchers understand how black holes produce jets.

    Fast-moving magnetic waves emanating from a distant supermassive black hole undulate like a whip whose handle is being shaken by a giant hand, according to a new study using data from the National Radio Astronomy Observatory’s Very Long Baseline Array.

    NRAO VLBA
    NRAO VLBA

    Scientists used this instrument to explore the galaxy/black hole system known as BL Lacertae (BL Lac) in high resolution.

    “The waves are excited by a shaking motion of the jet at its base,” said David Meier, a now-retired astrophysicist from NASA’s Jet Propulsion Laboratory and the California Institute of Technology, both in Pasadena.

    The team’s findings, detailed in the April 10 issue of The Astrophysical Journal, mark the first time so-called Alfven (pronounced Alf-vain) waves have been identified in a black hole system.

    Alfven waves are generated when magnetic field lines, such as those coming from the sun or a disk around a black hole, interact with charged particles, or ions, and become twisted or coiled into a helical shape. In the case of BL Lac, the ions are in the form of particle jets that are flung from opposite sides of the black hole at near light speed.

    “Imagine running a water hose through a slinky that has been stretched taut,” said first author Marshall Cohen, an astronomer at Caltech. “A sideways disturbance at one end of the slinky will create a wave that travels to the other end, and if the slinky sways to and fro, the hose running through its center has no choice but to move with it.”

    A similar thing is happening in BL Lac, Cohen said. The Alfven waves are analogous to the propagating sideways motions of the slinky, and as the waves propagate along the magnetic field lines, they can cause the field lines — and the particle jets encompassed by the field lines — to move as well.

    It’s common for black hole particle jets to bend — and some even swing back and forth. But those movements typically take place on timescales of thousands or millions of years. “What we see is happening on a timescale of weeks,” Cohen said. “We’re taking pictures once a month, and the position of the waves is different each month.”

    “By analyzing these waves, we are able to determine the internal properties of the jet, and this will help us ultimately understand how jets are produced by black holes,” said Meier.

    Interestingly, from the vantage of astronomers on Earth, the Alfven waves emanating from BL Lac appear to be traveling about five times faster than the speed of light, but it’s only an optical illusion. The illusion is difficult to visualize but has to do with the fact that the waves are traveling slightly off our line of sight at nearly the speed of light. At these high speeds, time slows down, which can throw off the perception of how fast the waves are actually moving.

    Other Caltech authors on the paper include Talvikki Hovatta, a former Caltech postdoctoral scholar. Scientists from the University of Cologne and the Max Planck Institute for Radioastronomy in Germany; the Isaac Newton Institute of Chile; Aalto University in Finland; the Astro Space Center of Lebedev Physical Institute, the Pulkovo Observatory, and the Crimean Astrophysical Observatory in Russia; Purdue University in Indiana and Denison University in Granville, Ohio.

    See the full article here.

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    NASA JPL Campus

    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge, on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 8:16 am on June 19, 2015 Permalink | Reply
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    From ALMA: “ALMA Weighs Supermassive Black Hole at Center of Distant Spiral Galaxy” 

    ESO ALMA Array
    ALMA

    18 June 2015
    Valeria Foncea
    Education and Public Outreach Officer
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 467 6258
    Cell: +56 9 75871963
    Email: vfoncea@alma.cl

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 434.242.9559
    E-mail: cblue@nrao.edu

    Richard Hook
    Public Information Officer, ESO
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory Tokyo, Japan
    Tel: +81 422 34 3630
    E-mail: hiramatsu.masaaki@nao.ac.jp

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    Composite image of the barred spiral galaxy NGC 1097. By studying the motion of two molecules, ALMA was able to determine that the supermassive black hole at the galactic center has a mass 140 million times greater than our Sun. The ALMA data is in red (HCO+) and green/orange (HCN) superimposed on an optical image taken by the Hubble Space Telescope. Credit: ALMA (NRAO/ESO/NAOJ), K. Onishi; NASA/ESA Hubble Space Telescope; NRAO/AUI/NSF

    Supermassive black holes lurk at the center of virtually every large galaxy. These cosmic behemoths can be millions to billions of times more massive than the Sun. Determining just how massive, however, has been daunting, especially for spiral galaxies and their closely related cousins barred spirals.

    In a new proof-of-concept observation, astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have measured the mass of the supermassive black hole at the center of NGC 1097 — a barred spiral galaxy located approximately 45 million light-years away in the direction of the constellation Fornax. The researchers determined that this galaxy harbors a black hole 140 million times more massive than our Sun. In comparison, the black hole at the center of the Milky Way is a lightweight, with a mass of just a few million times that of our Sun.

    Temp 1
    NGC 1097 observed in the optical light with VLT operated by ESO. Credit: ESO/R. Gendler

    See the full article here.

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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    ESO 50

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  • richardmitnick 3:23 pm on June 10, 2015 Permalink | Reply
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    From Chandra: “NGC 5813: Chandra Finds Evidence for Serial Black Hole Eruptions” 

    NASA Chandra

    June 10, 2015

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    Composite

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    X-ray

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    Optical
    Credit X-ray: NASA/CXC/SAO/S.Randall et al., Optical: SDSS
    Release Date June 10, 2015

    -Chandra data show the supermassive black hole at the center of NGC 5813 has erupted multiple times over 50 million years.
    -NGC 5813 is a group of galaxies that is immersed in an enormous reservoir of hot gas.
    -Cavities, or bubbles, in the hot gas that Chandra detects gives information about the black hole’s eruptions.
    -Chandra’s observations of NGC 5813 are the longest ever of a galaxy group taken in X-ray light.

    Astronomers have used NASA’s Chandra X-ray Observatory to show that multiple eruptions from a supermassive black hole over 50 million years have rearranged the cosmic landscape at the center of a group of galaxies.

    Scientists discovered this history of black hole eruptions by studying NGC 5813, a group of galaxies about 105 million light years [1 light year = about 6 trillion miles] from Earth. These Chandra observations are the longest ever obtained of a galaxy group, lasting for just over a week. The Chandra data are shown in this new composite image where the X-rays from Chandra (purple) have been combined with visible light data (red, green and blue).

    Galaxy groups are like their larger cousins, galaxy clusters, but instead of containing hundreds or even thousands of galaxies like clusters do, galaxy groups are typically comprised of 50 or fewer galaxies. Like galaxy clusters, groups of galaxies are enveloped by giant amounts of hot gas that emit X-rays.

    Local Group
    Milky Way’s Local [Galaxy] Group

    The erupting supermassive black hole is located in the central galaxy of NGC 5813. The black hole’s spin, coupled with gas spiraling toward the black hole, can produce a rotating, tightly wound vertical tower of magnetic field that flings a large fraction of the inflowing gas away from the vicinity of the black hole in an energetic, high-speed jet.

    The researchers were able to determine the length of the black hole’s eruptions by studying cavities, or giant bubbles, in the multi-million degree gas in NGC 5813. These cavities are carved out when jets from the supermassive black hole generate shock waves that push the gas outward and create huge holes.

    The latest Chandra observations reveal a third pair of cavities in addition to two that were previously found in NGC 5813, representing three distinct eruptions from the central black hole. (Mouse over the image for annotations of the cavities.) This is the highest number of pairs of cavities ever discovered in either a group or a cluster of galaxies. Similar to how a low-density bubble of air will rise to the surface in water, the giant cavities in NGC 5813 become buoyant and move away from the black hole.

    To understand more about the black hole’s history of eruptions, the researchers studied the details of the three pairs of cavities. They found that the amount of energy required to create the pair of cavities closest to the black hole is lower than the energy that produced the older two pairs. However, the rate of energy production, or power, is about the same for all three pairs. This indicates that the eruption associated with the inner pair of cavities is still occurring.

    Each of the three pairs of cavities is associated with a shock front, visible as sharp edges in the X-ray image. These shock fronts, akin to sonic booms for a supersonic plane, heat the gas, preventing most of it from cooling and forming large numbers of new stars.

    Close study of the shock fronts reveals that they are actually slightly broadened, or blurred, rather than being very sharp. This may be caused by turbulence in the hot gas. Assuming this is the case, the authors found a turbulent velocity – that is, the average speed of random motions of the gas – of about 160,000 miles per hour (258,000 kilometers per hour). This is consistent with the predictions of theoretical models and estimates based on X-ray observations of the hot gas in other groups and clusters.

    A paper describing these results was published in the June 1st, 2015 issue of The Astrophysical Journal and is available online. The first author is Scott Randall from the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, MA and the co-authors are Paul Nulsen, Christine Jones, William Forman and Esra Bulbul from CfA; Tracey Clarke from the Naval Research Laboratory in Washington DC; Ralph Kraft from CfA; Elizabeth Blanton from Boston University in Boston, MA; Lawrence David from CfA; Norbert Werner from Stanford University in Stanford, CA; Ming Sun from University of Alabama in Huntsville, AL; Megan Donahue from Michigan State University in East Lansing, MI; Simona Giacintucci from University of Maryland in College Park, MD and Aurora Simionescu from the Japan Aerospace Exploration Agency in Kanagawa, Japan.

    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 11:41 am on June 10, 2015 Permalink | Reply
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    From NYT: “An Earthling’s Guide to Black Holes” 

    New York Times

    The New York Times

    JUNE 8, 2015
    JOANNA KLEIN

    Welcome, earthlings, to the place of no return — a region in space where the gravitational pull is so strong, not even light can escape it. This is a black hole.

    It’s ok to feel lost here. Even [Albert] Einstein — whose Theory of General Relativity made it possible to conceive of such a place — thought the concept was too bizarre to exist. But Einstein was wrong, and here you are.

    You shouldn’t be here. You will surely get pulled in. But fear not dear Earthling, this is just your mind thinking. It has taken your brain millions of years to get here. So let’s get started.

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    Bright flares are visible near the event horizon of a super-massive black hole at the center of the Milky Way. Credit NASA/CXC, via MIT, via F.K.Baganoff

    The black hole is a hungry beast.

    It swallows up everything too close, too slow or too small to fight its gravitational force — even light. With every planet, gas, star or bit of mass consumed, the black hole grows.

    At the edge of a black hole, its event horizon, is the point of no return. Stay far away from the event horizon, because that’s where the hole pulls in light. And nothing is faster than light. At the event horizon, everything enters the black hole.

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    The brightest white spot in the middle is the very center of the Milky Way galaxy, which also marks the site of a supermassive black hole. Credit NASA/JPL-Caltech

    Pretty much everything we understand about how the universe works, depends on the black hole.

    Someone is wrong, or we have to admit that earthlings still aren’t equipped to understand the universe. The firewall paradox calls to question the most definitive theories of science. Albert Einstein, Joseph Polchinski or Stephen Hawking, or none, everything we know about the universe could change if we could know for certain what happens to information inside a black hole.

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    An interpretation of a black hole, created for an educational video game. Credit Denver Museum of Nature and Science

    If you fell into a black hole, it’s not clear how you would die.

    Will gravity rip you apart and crush you into the black hole’s core? Or will a firewall of energy sizzle you into oblivion? Could some essence of you ever emerge from a black hole? First posited by a group of theorists including Donald Marolf, Ahmed Almheiri, James Sully and Joseph Polchinski in March 2012, the question of how you would die inside a black hole is probably the biggest debate in physics right now. It’s called the firewall paradox.

    Based on the mathematics in Einstein’s 1915 General Theory of Relativity, you would fall through the event horizon unscathed before gravity’s force pulled you into a noodle and ultimately crammed you into singularity, the black hole’s infinitely dense core.

    But Dr. Polchinski and his team pitted Einstein against quantum theory, which posited that the event horizon would become a blazing firewall of energy that would torch your body to smithereens.

    Keep both theories, the physicist Stephen Hawking said in January 2014. Black holes aren’t what we thought they were. There is no event horizon, and there is no singularity. They’re just different.

    According to Dr. Hawking, at the edge of a black hole, the fourth dimension known as space-time fluctuates like weather, making the crisp edge we assume impossible. Instead, Dr. Hawking’s “apparent horizon” would be like a purgatory for light rays attempting to escape a black hole, slowly dissolving and moving inward, but never being pulled into singularity. The event horizon, he says, remains the same, or even shrinks as a black hole slowly leaks energy. Suspended in the apparent zone, you would scramble and leak out into the cosmos as “Hawking radiation.”

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    Galaxy NGC 1275. Credit NASA

    Black holes can sing.

    In 2003, an international team led by the X-ray astronomer Andrew Fabian discovered the longest, oldest, lowest note in the universe — a black hole’s song — using NASA’s Chandra X-ray Observatory.

    NASA Chandra Telescope
    Chandra

    Although it is too low and deep for humans to hear, the B flat note, 57 octaves below middle C, appeared as sound waves that moved out from explosive events at the edge of a supermassive black hole in the galaxy NGC 1275.

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    NGC 1275 per NASA/ESA Hubble

    The notes stayed in the galaxy and never reached us, but we couldn’t have heard them anyway. The lowest note the human ear can detect has an oscillation period of one-twentieth of a second. This B flat’s period was 10 million years.

    The “songs” of black holes may be behind a declining birth rate of stars in the universe. In clusters of galaxies such as Perseus, the home of NGC 1275, the energy these notes carry is thought to keep the gases too hot to condense and form stars.

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    A big galaxy gobbles a tiny one. Credit Swinburne University of Technology/Reuters

    Meet the management: Black holes may control the size of a galaxy.

    Playing music that keeps the intergalactic clusters too hot for stars might not be the only way black holes help maintain galaxies.

    Astronomers think that the energy that forms when galactic masses swirl and heat up around a black hole shoots out in X-ray beams that fuel quasars, supermassive black holes that are actively chomping down gas at the centers of distant galaxies.

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    The Milky Way as visible from the desert southwest of Cairo. Credit Amr Abdallah Dalsh/Reuters

    Astronomers have evidence for black holes in nearly every galaxy in the universe.

    Although no black hole is close enough to Earth to pull the planet into its depths, there are so many black holes in the universe that counting them is impossible. Nearly every galaxy — our own Milky Way as well as the 100 billion or so other galaxies visible from Earth — shows signs of a black hole.

    Of the billions of stars in the Milky Way, about one in every thousand new stars is massive enough to become a black hole. Our sun isn’t. But a star 25 times heavier is. Stellar-mass black holes result from the death of these stars, and can exist anywhere in the galaxy.

    Supermassive black holes — a million to a billion times more massive than our sun — exist only in the center of a galaxy. At the center of the Milky Way, 26,000 light-years from Earth, scientists are hoping to make an image of Sagittarius A*, which is believed to be our own supermassive black hole, with the mass of four million suns. How supermassive black holes form is still a mystery.

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    Sagittarius A* from NASA’s Chandra X-Ray Observatory

    Black holes are stellar tombstones.

    It wasn’t a nuclear bomb, and it wasn’t terrestrial. On July 2, 1967, a network of satellites recorded an explosion of gamma rays coming from outer space. In retrospect, this was one of the first indications that black holes are real. Today, scientists believe that the gamma ray burst is the final breath of a dying star and the birth of a stellar-mass black hole.

    The dramatic transformation starts when a massive star runs out of fuel to power itself. As the star begins to collapse, it explodes. The star’s outer layers spew out into space, but the inside implodes, becoming denser and denser, until there is too much matter in too little space. The core succumbs to its own gravitational pull and collapses into itself, in extreme cases forming a black hole.

    Theoretically, if you shrunk any mass down into a certain amount of space, it could become a black hole. Our earth would be one if you tried to cram the earth into a pea.

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    NASA’s Hubble Space Telescope captured a high energy blast, likely a black hole eating, at the center of a galaxy. Credit NASA

    ‘A black hole has no hair.’

    On March 28, 2011, astronomers detected a long gamma ray burst coming from the center of a galaxy four billion light-years away. This was the first time humans observed what might have been a dormant black hole eating a star.

    No matter what a black hole eats — a star, a donkey, an iPhone, your grammar teacher — it’s all the same. As the physicist John Archibald Wheeler put it, “A black hole has no hair,” meaning that a black hole remembers only the mass, spin and charge of its dinner.

    The more a black hole eats, the more it grows. In 2011, scientists discovered one of the biggest black holes ever, more than 300 million light-years away. It weighs enough to have gobbled up 21 billion suns. Scientists want to know if the biggest black holes are the result of two holes merging or one hole eating a lot. But scientists don’t know how they grew so large.

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    The Event Horizon Telescope is attempting to get the first ever portrait of the hungry monster at the center of our galaxy. Credit James D. Lowenthal/Smith College Astronomy Department

    To find the darkness, follow the light.

    Because light can’t escape a black hole, seeing what’s inside it is impossible. Getting a picture of a black hole’s edge is difficult, and getting a clear picture is an event.

    Actually, it has never been done. Scientists suspect black holes when their tools detect high-energy radio waves, such as those that may result from a collapsing star, gamma ray burst, supernova or the energy an object might release before reaching the black hole’s event horizon. Generally, if there is a lot of energy with a massive core at the center of a galaxy, the core is probably a black hole.

    The Event Horizon Telescope, the one Sheperd Doeleman and his colleagues used to try to photograph Sagittarius A* and M87, another black hole, featured a cast of more than 100 scientists on three continents and one very important crystal used to calibrate atomic clocks. The scientists staked out seven telescopes atop six mountains, synchronized time, pointed their discs at the sky and waited. For the first time ever, scientists may have seen a rough image of a black hole’s event horizon.

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    An artist’s conception of stars moving in the central regions of a giant elliptical galaxy that harbors a black hole. Credit Lynette Cook/Gemini Observatory, via Nature, via Associated Press

    A black hole is not forever.

    As Hawking radiation leaks out into the universe, quantum effects suggest that a black hole will evaporate — eventually. It would take many times the age of the universe for a black hole to fully evaporate.

    Dr. Hawking, like Einstein, at first did not believe his own theory. But the numbers were right. Physicists now view his result as the backbone for whatever future theory will bring together gravity and quantum theory.

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    This magnet is part of The Large Hadron Collider, the world’s largest and most powerful particle accelerator. [at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. ] Credit Fabrice Coffrini/Agence France-Presse — Getty Images

    A giant magnet in Europe will not destroy the planet.

    Before the European Organization for Nuclear Research fired up the Large Hadron Collider in 2008, critics worried that smashing together protons in a 17-mile ring underground would create a black hole that would swallow the earth.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Worriers echoed apocalyptic cries about Brookhaven National Laboratory’s Relativistic Heavy Ion Collider that the center’s scientists had squelched nearly 10 years earlier.

    BNL RHIC Campus
    BNL RHIC
    RHIC at BNL

    According to their calculations, ultrahigh-energy cosmic rays already penetrated the earth’s atmosphere and predicted about 100 tiny black holes on earth every year. If tiny black holes were a problem, Earth would have already collapsed into infinity:

    Still, in June 2008, a safety review proclaimed the L.H.C. was indeed safe. Experiments commenced, the Higgs boson was found, and the earth survived after all.

    In the search for the smallest particles in the universe, the consequential mini black holes that scientists might create in contained underground tubes would let them observe general relativity and quantum mechanics in action and may open the door to solving the firewall paradox.

    See the full article here.

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  • richardmitnick 9:20 am on June 10, 2015 Permalink | Reply
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    From NYT: “Black Hole Hunters” 

    New York Times

    The New York Times

    JUNE 8, 2015
    Dennis Overbye

    Sheperd Doeleman’s project to take the first-ever picture of a black hole wasn’t going well.

    For one thing, his telescope kept filling with snow.

    For two weeks at the end of March, Volcan Sierra Negra, an extinct 15,000-foot volcano also known as Tliltepetl that looms over the landscape in southern Mexico, was the nerve center for the largest telescope ever conceived, a network of antennas that reaches from Spain to Hawaii to Chile.

    Known as the Event Horizon Telescope, named after the point of no return in a black hole, its job was to see what has been until now unseeable: an exquisitely small, dark circle of nothing, a tiny shadow in the glow of radiation at the center of the Milky Way galaxy. It is there that astronomers think lurks a supermassive black hole, a trap door into which the equivalent of four million suns has evidently disappeared.

    Nature, Albert Einstein once said, is not malicious, only subtle. But it loves a good fight.

    Lightning greeted Dr. Doeleman and his crew of astronomers late one night as they crested the summit of their outpost in the unfriendly sky.

    What little air there was tasted the way you might imagine it would on Mars. Snowflakes swirled around their heads. The Large Millimeter Telescope [LMT], a 20-story tower with a 150-foot-wide bowl-shaped antenna sitting like an oversize cocked hat on its roof, was barely visible in the gloom.

    Large Millimeter Telescope Alfonso Serrano
    LMT

    The astronomers stepped gingerly out of their cars onto a moonscape of rocks and down a ramp into the telescope’s basement, a labyrinth of warmly lit rooms and labs, as if entering the lair of a James Bond villain.

    Dr. Doeleman had planned to spend the night working out new techniques to point the telescope, which among its other problems was afflicted by a persistent and annoying electrical hum. By the time the weather had cleared enough, the radio dish was frozen solid underneath an inch of ice. The stars whirled above, past the remains of storm clouds, their secrets unscathed.

    “This is par for us,” Dr. Doeleman, a fresh-faced 48-year-old researcher from M.I.T.’s Haystack Observatory and the Harvard-Smithsonian Center for Astrophysics, said with a mix of resignation and pride.

    2
    Sheperd Doeleman, seated at left, and other scientists monitored data in the control room of the Large Millimeter Telescope. Credit Meridith Kohut for The New York Times

    If he and his colleagues succeed, the images they capture will be in textbooks forever, as definitive evidence of Einstein’s weirdest prediction: that space-time could curl up like a magician’s cloak around massive objects and vanish them from the universe. In short, that black holes — objects so dense that not even light can escape their maws — are real. That space and time as we know them can come to an end right under our noses.

    Conversely, they could produce evidence that Einstein’s theory of gravity, general relativity, the rule of rules for the universe, needs fixing for the first time since it was introduced a hundred years ago.

    “We’re swinging for the fences,” Dr. Doeleman, who has spent eight years putting this effort together, said one afternoon in an office in Serdan, a small town at the volcano’s base.

    He was dressed in long johns and layers of sweaters and fleece, and sipped coca-leaf tea to combat the effects of altitude. He was sweaty, and his hair stood on end in an Einsteinian Mohawk after a long night trying to troubleshoot his telescope.

    “We have to worry about everything, from soup to nuts,” he said, ticking off all the things that make this radio network, stretched like a spider web across the planet, a fragile object. Success hinges on the exigencies of weather on several continents, high-strung technology, altitude, even traffic — two of his colleagues had just been delayed in a car accident on the way from Mexico City.

    “I guess spider silk is stronger than steel,” he said, “but even spider silk can snap.”

    3
    The Large Millimeter Telescope is on the summit of the dormant volcano Sierra Negra in Mexico at an altitude of 15,092 feet. Credit Meridith Kohut for The New York Times

    The Cosmic Roach Motel

    Black holes were one of the first and most extreme predictions of Einstein’s General Theory of Relativity, first announced in November 1915. It explains the force we call gravity as objects trying to follow a straight line through a universe whose geometry is warped by matter and energy. As a result, planets as well as light beams follow curving paths, like balls going around a roulette wheel.

    Einstein was taken aback a few months later when Karl Schwarzschild, a German astronomer then serving on the Russian front, pointed out that the equations contained an apocalyptic prediction: Cramming too much matter and energy inside too small a space would cause space-time to sag without limit. No force known to science could stop it from becoming a sinkhole from which not even light could escape.

    Einstein could not fault the math, but he figured that in real life, nature would find some way to avoid such a calamity. A century later, however, astronomers agree that space is indeed sprinkled with massive objects that emit no light at all. Call them cosmic roach motels. Stars, atoms, wisps of gas that trace their pedigree to the Big Bang — all of them check in, never to check out.

    Many of them are supposed to be the remnants of massive stars that have burned out, collapsed and imploded in cataclysms like supernovas or the even more violent gamma-ray bursts visible across the universe.

    Generations of theorists, including Stephen Hawking, using the telescope of the mind, have made careers investigating the properties of these objects only barely in the universe. But they are still arguing about just what happens inside a black hole and the ultimate fate of whatever falls in.

    Nearly every galaxy seems to harbor one of these dark monsters, millions or even billions of times as massive as the sun, squatting at its center like Dante’s devil. The bigger the galaxy, for some reason, the more massive the void inside it. How that happens is a cosmic nature-versus-nurture question, and anyone’s guess.

    “How does a black hole know how big a galaxy it’s in and when to stop growing?” mused David Hughes, the director of the Large Millimeter Telescope, “or, conversely, how does the galaxy know to stop feeding it?”

    Left by themselves, black holes lie dormant with their mouths open. But when something — say, a wayward star or gas cloud — does fall toward a black hole, it is heated to billions of degrees as it swirls in a doughnut called an accretion disk around the cosmic drain. Black holes are sloppy eaters, and when they feed, jets of X-rays and radio energy can be squeezed like toothpaste out of a tube from the accretion disks. Astronomers believe this is what produces the energies of quasars, brilliant beacons in the cores of galaxies that far outshine the starry cities in which they dwell. “Paradoxically,” Dr. Doeleman said, “that makes black holes some of brightest things in the sky.”

    Last winter, a team of astronomers from Beijing University and the University of Arizona announced that they had discovered one of the biggest, baddest black holes yet — 10 billion times as massive as the sun, anchoring a quasar that was blazing 40,000 times brighter than the Milky Way when the universe was only a billion years old.

    Not all the action is so far, far away.

    The center of the Milky Way, 26,000 light-years from here, coincides with a faint source of radio noise called Sagittarius A*.

    13
    Sgr A* (centre) and two light echoes from a recent explosion (circled)

    Astronomers like U.C.L.A.’s Andrea Ghez tracking the orbits of stars circling the center have been able to calculate that whatever is at the center has the mass of four million suns. But it emits no visible or infrared light.

    If this is not a black hole, neither Einstein nor anyone else knows what it could be.

    “That is the strongest evidence so far for an event horizon,” Dr. Doeleman said, using the name for the boundary of a black hole, the edge that is the point of no return.

    But that is only a circumstantial argument, assuming that Einstein was right. “If Einstein was wrong, how would we know?” said Avery Broderick, a theorist at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, noting that general relativity, for all its mathematical beauty, had never been tested under the extreme conditions that would prevail in the Big Bang or black holes, where the full weirdness of Einsteinian space-time would manifest itself.

    According to work that goes back to a paper by James Bardeen in 1967, the Sagittarius black hole, if it is there, would appear as a ghostly dark circle amid a haze of radio waves. Its exact shape, the theorists say, would depend on details like how fast the hole is spinning.

    The black hole’s own gravity will distort and magnify its image, resulting in a shadow about 50 million miles across, appearing about as big from here as an orange would on the moon, according to calculations performed by Eric Agol of the University of Washington, Heino Falcke of the Max Planck Institute for Radio Astronomy in Germany and Fulvio Melia of the University of Arizona, in 2000.

    The proof of the pudding for Einstein would be if radio astronomers could determine that the shadow, the graveyard of four million suns, really was that small. They have been whittling its size ever since Sagittarius A* was discovered, in 1974.

    3
    Scientists checking the Large Millimeter Telescope for ice on its dish. Inclement weather interferes with the telescope’s functioning. Credit Meridith Kohut for The New York Times

    In 2005, a group led by Shen Zhiqiang of the Shanghai Astronomical Observatory narrowed the diameter of Sagittarius A* to a cloud of energy less than 90 million miles across, about twice the size of the long-sought shadow, using the Very Long Baseline Array, a transcontinental network of antennas.

    NRAO VLBA
    VLBA

    “For most people, seeing is believing,” Dr. Agol said at the time. But there was a problem getting measurements any finer. The ionized electrons and protons in interstellar space scattered the radio waves into a blur that obscured details of the source. “It’s like looking through frosted glass,” Dr. Doeleman said.

    To see deeper into the black hole shadow, they needed to be able to tune their radio telescope to shorter wavelengths that could penetrate the haze. And they needed a bigger telescope. The bigger the antenna, the higher resolution or magnification it can achieve.

    “Our black hole is active but eating on a slow diet, with billion-degree gas around it,” Dr. Doeleman said. The result, at the heart of the Milky Way, is “a puffy cloud,” he said. “You need the right frequency to see through the debris at the galactic center.”

    Enter the Event Horizon Telescope.

    On the Edge

    Dr. Doeleman had taken a wandering path to the edge of infinity.

    The son of a science teacher, he grew up in Oregon and studied physics at Reed College in Portland. He applied to attend graduate school at the Massachusetts Institute of Technology, but before he could go, he saw an ad looking for people to do experiments in the Antarctic. He signed up and spent most of a couple of years at the bottom of the world. “It was there that I probably caught the bug for doing science under challenging circumstances,” Dr. Doeleman said. He reapplied to M.I.T. from Antarctica and then wandered around Asia on his way home.

    At M.I.T., he first joined a group doing plasma physics, then dabbled in X-ray astronomy and biophysics before joining a radio astronomy group. The technique of choice for radio astronomers is known by the intimidating name of very long baseline interferometry — V.L.B.I. for short — in which separate radio telescopes as far as a continent apart can be joined in a synchronized network that mimics a single antenna with a very big diameter.

    Dr. Doeleman was originally interested in using the technology to monitor movements of the Earth’s crust and was hoping to travel to exotic places to install instruments. But it turned out they were already installed. So his eyes turned to the heavens and the mysteries of quasars.

    During a talk recently, Dr. Doeleman showed a picture of a galaxy in the constellation Centaurus, a gentle-looking pearly smoosh of starlight with a slash of dust across its belly. Known as NGC 5128, the galaxy can be seen through binoculars from the Southern Hemisphere.

    Then he showed a picture of the same galaxy taken through what he called “radio goggles.” In this view, the galaxy is being ripped apart by an explosion at its core, shooting lobes of energy thousands of light-years across space.

    Dr. Doeleman traced his interest in quasars and black holes to the moment he first saw images like that. “Whatever is powering those jets has to be insanely powerful,” he said.

    In 2008, Dr. Doeleman had what he calls an “a-ha moment” when he and colleagues yoked together three radio telescopes in Hawaii, Arizona and California into a interferometer system and trained it on the galactic center, using a shorter wavelength. They detected a small blob of energy, “a dot that would not go away.”

    They were seeing something through the frosted glass. But what?

    Since then, he and his colleagues have devoted their energies to building a network big enough to see whether that radio dot harbors signs of a black hole.

    In all, the Event Horizon Telescope involves 20 universities, observatories, research institutions and government agencies, and more than a hundred scientists. Among other things, to keep the radio telescopes in their network suitably synchronized, they had to equip them with new atomic clocks accurate to within one second every 100 million years, and new short-wavelength receivers.

    Dr. Doeleman recalled having to wear an oxygen tank to test atomic clocks at the new ALMA array, on a 16,000-foot plateau in Chile. Another colleague, Daniel Marrone of the University of Arizona, spent last winter at the South Pole installing a new receiver. Both of these installations will eventually join the Event Horizon observations.

    The March observing run was the first time the group would have enough telescopes — seven radio telescopes, on six mountains — to begin to hope they could glimpse the black hole. They would have five chances over a period of two weeks.

    On each night, they hoped to have two black holes in their sights: Sagittarius A*, and one in a giant galaxy known as M87, which anchors the enormous Virgo cluster of galaxies about 50 million light-years away. The M87 black hole has been estimated at six billion times the mass of the sun, and from here, it would appear only slightly smaller than the Milky Way black hole. Moreover, jets of energy shoot like a blowtorch from its accretion disk and across intergalactic space. Astronomers really wanted to get a close look at that.

    6
    The Large Millimeter Telescope is the nerve center for the Event Horizon Telescope, a network of antennas that make up the largest telescope ever. Credit Meridith Kohut for The New York Times

    Hoping for Boredom

    “It’s beautiful work,” Andrew Strominger, a Harvard theorist who has joined the Event Horizon team, said of the telescope.

    In practice, it could be gritty or boring, depending on how things were going.

    The visit to Sierra Negra in March was Dr. Doeleman’s fifth in two years. The commute required a plane ride and five hours in buses, cars and trucks to the small, decidedly untouristic town of Serdan. He sometimes toted a special crystal used to test atomic clocks, which provoked attention from security officers. “It looks just like you would expect a bomb to look — a metal cylinder with wires sticking out,” he said.

    For his troubles, he often wound up with a headache, the price of working almost three miles above sea level. The telescope control room is outfitted with finger monitors that measure blood oxygen and an oxygen tank and mask for those woozy moments.

    Sierra Negra is next door to an even bigger peak, Pico de Orizaba, Mexico’s highest mountain, and the pair combine to create their own weather, which can cause problems for astronomers.

    One night, the telescope was being turned to keep it from filling with snow. Dr. Doeleman was in the unheated receiver room, where light from the antenna’s focus bounces off mirrors down an open shaft into boxes the size of microwave ovens, when he felt the building shake. Thinking it might be an earthquake, Dr. Doeleman ran for the elevator, only to find his colleagues rushing up from the control room and offices below. “I was pretty freaked,” he said.

    It was no earthquake. Because of an electrical malfunction, the gargantuan dish, half a football field wide and weighing 1,600 metric tons, had suddenly lurched to a stop, transferring all that momentum to the structure around it.

    Later on, a real earthquake sent the astronomers running from their breakfasts down in Serdan.

    In late March, Dr. Doeleman’s collaborators were camped out on similarly uncomfortable mountains in Chile, Hawaii, California, Arizona and Spain, waiting for his signal, based on weather forecasts and the state of their equipment — all the accouterments of that spider silk — to begin observing. All the telescopes would point in unison at M87, and then at the galactic center.

    When it works well, this ganging up on the cosmos is “boring, in a good way,” Dr. Doeleman said one night that was anything but boring, explaining that the observations best proceed automatically while the astronomers all hold their breath.

    Belying the boredom is the hope that in the subtle interplay of radio waves they will see the signature of one of nature’s great calamities. Waves from different parts of the radiation cloud around Sagittarius A* would interfere with one another, producing a complicated pattern that a computer could read as a black hole.

    Imagine, Dr. Doeleman said, that someone is dipping a finger into a pond and creating ripples. If there were tidal gauges installed along the shore, you could figure out where the ripples were coming from by recording the arrival of each wave crest on the shore. One finger would make concentric circles.

    If there were two fingers doing the dipping, the ripples would interfere with one another, sometimes amplifying, sometimes canceling out. As a result, some tidal gauges would show crests combining to be extra large; others would show troughs.

    “By analyzing this pattern,” Dr. Doeleman said, “we can tell what’s going on far away.” Someone reading the pattern could distinguish whether there was just one finger or many of them in some arrangement dappling the water.

    In this case, there are antennas spread along the shore of infinity, synchronized by atomic clocks, recording the radio waves as they arrive.

    “This is the way you build a telescope as big as the world,” Dr. Doeleman said.

    7
    Sheperd Doeleman working inside the heart of the Large Millimeter Telescope to verify the alignment of a radio wave receiver. Credit Meridith Kohut for The New York Times

    If everything went right — if all the elements of Dr. Doeleman’s spider web of weather and electronics and superprecise timing held together — they would see that any given wavefront would arrive bearing the marks of interference, a complicated pattern of crests and troughs — “fringes,” in the astronomical vernacular. With enough fringes from baselines going in different directions across the sky from the various observatories, the astronomers could reconstruct a map what was happening out there, thousands of millions of light-years away.

    Seeing even one fringe from one baseline would be a triumph — it would mean they were achieving the kind of resolution needed to make a detailed image of Sagittarius A* and see if it looks like a black hole. Making that image, of course, would be another long story indeed. Until they saw that first fringe, the Event Horizon team would simply have to hold their breaths.

    That could be months. All that data would be too much to send over the Internet. Nobody would know if the whole telescope had worked until the data recorded from each separate instrument had been correlated in a supercomputer back at M.I.T. As Dr. Doeleman liked to say, “The bandwidth of a 747 loaded with disk drives is phenomenal.”

    If they are lucky, sometime later this summer or fall, then, they might see emerging from the computers at M.I.T. the first rough image of a black hole. And its size and shape could provide a judgment on general relativity, the harshest test yet a century after Einstein dreamed up the theory.

    For some theorists, breaking Einstein is the main game. “The least exciting thing would be to find general relativity works beautifully,” said Dr. Broderick, at the Perimeter Institute.

    But Dr. Doeleman says he is also excited about what he likes to call the “secret sauce” of the Event Horizon Telescope: the chance to see inside the engine that produces the monstrous energies of quasars.

    “We can see a black hole eat in real time,” he said. By following hot spots in the superhot gas swirling toward oblivion, they can even measure the rotation rate of the black hole.

    8
    This infrared image from NASA’s Spitzer Space Telescope shows the center of the Milky Way galaxy, where the Event Horizon Telescope team hopes to find details of the black hole that scientists believe lurks there. Credit NASA/JPL-Caltech

    “If something is dancing around the edge of the black hole, it doesn’t get any more fundamental than that,” Dr. Doeleman said. “Hopefully we’ll find something amazing.”

    The Plumbers’ Blues

    The first piece of Dr. Doeleman’s spider silk to break was the radio telescope in Chile. Its receiver died and had to be sent back to Europe for repairs.

    That failure put more of an onus on the Mexican telescope.

    Sierra Negra was a natural choice as the fulcrum of the Event Horizon Telescope. Not only is it centrally located, but the new Large Millimeter Telescope, with its giant dish designed for short wavelengths, is also the most sensitive radio telescope in the network. Completed in 2006 by the National Institute of Astrophysics, Optics and Electronics in Puebla state and the University of Massachusetts, Amherst, at a cost of $116 million, it is the largest and most expensive scientific project in Mexico. Its inclusion in the Event Horizon Telescope was a point of great pride to its director, Dr. Hughes, who has spent the better part of the last decade getting the instrument up to snuff.

    “People want to bring their equipment and their experiments here now,” he said.

    During a dry run, however, the astronomers discovered that the telescope’s new receiver was afflicted by a mysterious electrical buzz.

    Astronomical history is replete with mysterious hisses and buzzes that turn out to be cosmic breakthroughs. One incident 50 years ago with two Bell Labs astronomers, Arno Penzias and Robert Wilson, turned out to be the signal of cooling radiation from the Big Bang itself, and resulted in a Nobel Prize.

    But this was not the cosmos calling. The hum did not interfere with the data, but it did interfere with pointing the antenna. Normally, to lock onto a radio source, the astronomers would rock the telescope back and forth to find the strongest signal, like a cross-country driver trying to tune into a distant Yankees game.

    The Event Horizon Telescope

    A network of telescopes as big as the Earth is trying to measure the boundary of what astronomers suspect is a supermassive black hole at the center of our Milky Way galaxy. Placing the telescopes as far apart as possible increases the array’s ability to discern small details and effectively increases the resolution of the resulting images.

    Strong sources like Jupiter still came booming through above the noise. But the buzz was louder than faint sources like Sagittarius A* at the galactic center, meaning that the astronomers could not be sure they were recording data from the right target. As a result, the Mexican telescope had to sit out the first official observing run.

    Several days of troubleshooting failed to make the buzz go away. “We’re just plumbers here,” Dr. Doeleman said one morning.

    To make matters worse, the expert on the receiver, Gopal Narayanan of the University of Massachusetts, was called home for a family emergency.

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    If the astronomers did not solve the problem, they would be down to just four sites in the network. “Every antenna is precious,” Dr. Doeleman said, but the prolonged absence of the Large Millimeter Telescope could be crippling. Losing Mexico on top of Chile would leave the astronomers with less than half the information they had hoped for.

    “We’re on a slippery slope,” Dr. Doeleman said.

    He and his colleagues hit on a plan. Unable to isolate the noise, they decided to see if they could use a less sensitive but quieter receiver to point the telescope, and then switch over to the new receiver to collect data. They could calibrate the pointing difference between the receivers by aiming each one in turn at a bright object like Saturn and measuring the offset.

    “It’s a lot of handwork,” Dr. Doeleman said. “Once you know the offset, you can lock in with a computer model.”

    “What do I feel about this project?” Dr. Doeleman said that afternoon as the team was assembling to go back up to the telescope, raising his voice so everyone could hear. “We’re going to succeed. It’s going to take a lot of innovation, but we have a good team to do it.”

    At the time, Dr. Doeleman was not planning on being part of that team. He was scheduled to go home to his family the next morning, having already extended his stay in Mexico once.

    Dr. Hughes urged him to stay, saying the team needed his leadership and expertise.

    Doing so would require an intense Skype conversation with his family, Dr. Doeleman said.

    Dr. Hughes replied that it should be an easy decision, given the scientific consequences.

    The Kid Stays in the Picture

    Dr. Doeleman packed his bags for the long ride to the airport. But in the morning, looking distraught, he announced he had changed his mind and would stay.

    Two of his postdocs were new to observational astronomy, the Mexican scientists who had joined them were new to the Event Horizon procedures, and Dr. Narayanan, the receiver expert, was not back yet. The telescope’s chances of helping to produce a black hole image were hanging in the balance. “If we were going to have any chance of doing it, I had to stay,” Dr. Doeleman said.

    His reward was another night of snow in the dish, a real heartbreaker because for the first time, everything else was working.

    Twelve hours later, the team made its third try. The atmosphere in the control room was almost giddy as the telescope swung into position, staring at the black hole in the fiery galaxy M87.

    11
    Sheperd Doeleman, second from left, watching data being received inside the control room of the Event Horizon Telescope network. Credit Meridith Kohut for The New York Times

    Dr. Doeleman, wearing a scarf knitted by his wife, typed into his laptop that the Large Millimeter Telescope was taking data. At last.

    “That’s a real moment,” he told Dr. Narayanan, who had just returned from home. “That’s a real moment, Gopal. That’s huge.

    “We’re gonna image a black hole,” he said, beaming. “That’s what we’re here for. This is it. We’re doing it.”

    The connection established, they settled down to be bored — but an hour later, the weather went bad and they had to stow the telescope to keep the snow out.

    Just before dawn, five long hours later, the weather cleared enough for the telescope to rejoin the network, now focused on the Milky Way center.

    Laura Vertatschitsch, one of Dr. Doeleman’s postdoctoral researchers at the Center for Astrophysics, said, “My heart was beating a million miles a minute, and I was smiling from ear to ear.”

    High-fives were exchanged — but two hours later, the sun had risen too high for them to continue. The black-hole party now became a race against time and weather. The next night, the Mexican telescope was shut out by the weather completely.

    As Dr. Doeleman put it later in an email, “There were a couple of nights where the other sites were having an E.H.T. party and we were at home in PJs doing the crossword. Maddening.”

    Getting Out of Dodge

    Dr. Doeleman did finally go home, satisfied that his team was in good shape to carry on, while he watched by laptop and Skype. Dr. Narayanan took apart the receiver and traced the troublesome noise to mechanical vibrations, which he treated with duct tape. After all, he said, duct tape had helped save Apollo 13.

    Naturally, that was when things started working.

    They were now down to their last official chance to spin the silk. The weather was not promising, Dr. Vertatschitsch said later by email, but they went up Sierra Negra anyway. They spent half the night going through their piggyback routine to point the telescope, writing computer code on the spot. “It’s hard to describe,” she wrote, “but there is an adrenaline that comes with this high-stakes problem-solving.”

    Then they clicked with the Event Horizon Telescope for good, first for Virgo and then for Sagittarius, collecting data until dawn. Afterward, some of the astronomers ran out and took a selfie in front of the telescope, celebrating, Dr. Vertatschitsch said in an email, “the sweat, the lack of sleep, the exhaustion and the pure joy of an experiment. It’s the moments you live for.”

    12
    Members of the Large Millimeter Telescope team taking a selfie.

    From afar, Dr. Doeleman had his own moment. “I wasn’t there,” he said later. “Sometimes, the best thing you can do is get out of Dodge.”

    That night marked the end of the Event Horizon Telescope’s official observing run, but as it happened, there was an encore. California, Arizona and Mexico were available for an extra night. That, said Dr. Vertatschitsch, was the best night of all.

    “It was the best weather we had seen all trip,” she said. Dr. Narayanan’s taped-up receiver was able to do the pointing by itself.

    “All I had to do was go,” Dr. Doeleman said later. “On the final two nights, the clouds parted. Everything comes out biblical in the Event Horizon Telescope.”

    A Sneak Peek

    Two weeks later, Dr. Doeleman, looking relaxed and 20 years younger, with his wife and two children in tow, traveled to New York to give a talk in the Hayden Planetarium at the American Museum of Natural History. He said in a separate conversation that some 200 terabytes of data — about as much as is contained in the printed material in the Library of Congress — were then on the way to M.I.T., the bandwidth of that metaphorical 747 in action.

    This year, the 100th since Einstein presented his Theory of General Relativity, the calendar is chock-full of meetings and celebrations devoted to the theory. Perhaps during this yearlong party, astronomers may finally know if the dark shadow of eternity is smiling at us through the star clouds of Sagittarius.

    The computers are already running.

    At the end of April, an email went out to the Event Horizon collaboration, dense with graphs, the result of correlating the observations from one night between two mountains — Sierra Negra and Mauna Kea, in Hawaii.

    They showed striking signs of an interference pattern. The fringes were there. The spider silk had held.

    “I had no idea I could hold my breath that long!” Dr. Doeleman said.

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  • richardmitnick 11:43 am on June 2, 2015 Permalink | Reply
    Tags: , , , Supermassive Black Holes   

    From Hubble: “Merging galaxies break radio silence” 

    NASA Hubble Telescope

    Hubble

    28 May 2015
    Contacts
    Marco Chiaberge
    Space Telescope Science Institute, USA
    Johns Hopkins University, USA, INAF-IRA, Italy
    Tel: +1 410 338 4980
    Email: marcoc@stsci.edu

    Roberto Gilli
    INAF
    Osservatorio Astronomico di Bologna, Italy
    Tel: +39 051 2095 719
    Cell: +39 347 4139847
    Email: roberto.gilli@oabo.inaf.it

    Mathias Jäger
    ESA/Hubble, Public Information Officer
    Garching bei München, Germany
    Cell: +49 176 62397500
    Email: mjaeger@partner.eso.org

    1

    In the most extensive survey of its kind ever conducted, a team of scientists have found an unambiguous link between the presence of supermassive black holes that power high-speed, radio-signal-emitting jets and the merger history of their host galaxies. Almost all of the galaxies hosting these jets were found to be merging with another galaxy, or to have done so recently. The results lend significant weight to the case for jets being the result of merging black holes and will be presented in the Astrophysical Journal.

    A team of astronomers using the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3) have conducted a large survey to investigate the relationship between galaxies that have undergone mergers and the activity of the supermassive black holes at their cores.

    NASA Hubble WFC3
    WFC3

    The team studied a large selection of galaxies with extremely luminous centres — known as active galactic nuclei (AGNs) — thought to be the result of large quantities of heated matter circling around and being consumed by a supermassive black hole. Whilst most galaxies are thought to host a supermassive black hole, only a small percentage of them are this luminous and fewer still go one step further and form what are known as relativistic jets [1]. The two high-speed jets of plasma move almost with the speed of light and stream out in opposite directions at right angles to the disc of matter surrounding the black hole, extending thousands of light-years into space. The hot material within the jets is also the origin of radio waves.

    It is these jets that Marco Chiaberge from the Space Telescope Science Institute, USA (also affiliated with Johns Hopkins University, USA and INAF-IRA, Italy) and his team hoped to confirm were the result of galactic mergers [2].

    The team inspected five categories of galaxies for visible signs of recent or ongoing mergers — two types of galaxies with jets, two types of galaxies that had luminous cores but no jets, and a set of regular inactive galaxies [3].

    “The galaxies that host these relativistic jets give out large amounts of radiation at radio wavelengths,” explains Marco. “By using Hubble’s WFC3 camera we found that almost all of the galaxies with large amounts of radio emission, implying the presence of jets, were associated with mergers. However, it was not only the galaxies containing jets that showed evidence of mergers!” [4].

    “We found that most merger events in themselves do not actually result in the creation of AGNs with powerful radio emission,” added co-author Roberto Gilli from Osservatorio Astronomico di Bologna, Italy. “About 40% of the other galaxies we looked at had also experienced a merger and yet had failed to produce the spectacular radio emissions and jets of their counterparts.”

    Although it is now clear that a galactic merger is almost certainly necessary for a galaxy to host a supermassive black hole with relativistic jets, the team deduce that there must be additional conditions which need to be met. They speculate that the collision of one galaxy with another produces a supermassive black hole with jets when the central black hole is spinning faster — possibly as a result of meeting another black hole of a similar mass — as the excess energy extracted from the black hole’s rotation would power the jets.

    “There are two ways in which mergers are likely to affect the central black hole. The first would be an increase in the amount of gas being driven towards the galaxy’s centre, adding mass to both the black hole and the disc of matter around it,” explains Colin Norman, co-author of the paper. “But this process should affect black holes in all merging galaxies, and yet not all merging galaxies with black holes end up with jets, so it is not enough to explain how these jets come about. The other possibility is that a merger between two massive galaxies causes two black holes of a similar mass to also merge. It could be that a particular breed of merger between two black holes produces a single spinning supermassive black hole, accounting for the production of jets.”

    Future observations using both Hubble and the Atacama Large Millimeter/submillimeter Array (ALMA) are needed to expand the survey set even further and continue to shed light on these complex and powerful processes.

    ALMA Array
    ALMA

    Notes

    [1] Relativistic jets travel at close to the speed of light, making them one of the fastest astronomical objects known.

    [2] The new observations used in this research were taken in collaboration with the 3CR-HST team. This international team of astronomers is currently led by Marco Chiaberge and has conducted a series of surveys of radio galaxies and quasars from the 3CR catalogue using the Hubble Space Telescope.

    [3] The team compared their observations with the swathes of archival data from Hubble. They directly surveyed twelve very distant radio galaxies and compared the results with data from a large number of galaxies observed during other observing programmes.

    [4] Other studies had shown a strong relationship between the merger history of a galaxy and the high levels of radiation at radio wavelengths that suggests the presence of relativistic jets lurking at the galaxy’s centre. However, this survey is much more extensive, and the results very clear, meaning it can now be said with almost certainty that radio-loud AGNs, that is, galaxies with relativistic jets, are the result of galactic mergers.

    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 3:39 pm on May 1, 2015 Permalink | Reply
    Tags: , , , Supermassive Black Holes   

    From Chandra: “NASA’s Chandra Suggests Black Holes Gorging at Excessive Rates” 

    NASA Chandra

    April 30, 2015
    Jennifer Harbaugh

    1
    Illustration: CXC/M. Weiss
    X-ray images: NASA/CXC/Penn State/B. Luo et al.

    A group of unusual giant black holes may be consuming excessive amounts of matter, according to a new study using NASA’s Chandra X-ray Observatory. This finding may help astronomers understand how the largest black holes were able to grow so rapidly in the early Universe.

    Astronomers have known for some time that supermassive black holes − with masses ranging from millions to billions of times the mass of the Sun and residing at the centers of galaxies − can gobble up huge quantities of gas and dust that have fallen into their gravitational pull. As the matter falls towards these black holes, it glows with such brilliance that they can be seen billions of light years away. Astronomers call these extremely ravenous black holes “quasars.”

    This new result suggests that some quasars are even more adept at devouring material than scientists previously knew.

    “Even for famously prodigious consumers of material, these huge black holes appear to be dining at enormous rates, at least five to ten times faster than typical quasars,” said Bin Luo of Penn State University in State College, Pennsylvania, who led the study.

    Luo and his colleagues examined data from Chandra for 51 quasars that are located at a distance between about 5 billion and 11.5 billion light years from Earth. These quasars were selected because they had unusually weak emission from certain atoms, especially carbon, at ultraviolet wavelengths. About 65% of the quasars in this new study were found to be much fainter in X-rays, by about 40 times on average, than typical quasars.

    The weak ultraviolet atomic emission and X-ray fluxes from these objects could be an important clue to the question of how a supermassive black hole pulls in matter. Computer simulations show that, at low inflow rates, matter swirls toward the black hole in a thin disk. However, if the rate of inflow is high, the disk can puff up dramatically, because of pressure from the high radiation, into a torus or donut that surrounds the inner part of the disk.

    “This picture fits with our data,” said co-author Jianfeng Wu of the Harvard-Smithsonian Center for Astrophysics, in Cambridge, Massachusetts. “If a quasar is embedded in a thick donut-shaped structure of gas and dust, the donut will absorb much of the radiation produced closer to the black hole and prevent it from striking gas located further out, resulting in weaker ultraviolet atomic emission and X-ray emission.”

    The usual balance between the inward pull of gravity and the outward pressure of radiation would also be affected.

    “More radiation would be emitted in a direction perpendicular to the thick disk, rather than along the disk, allowing material to fall in at higher rates,” said co-author Niel Brandt, also of Penn State University.

    The important implication is that these “thick-disk” quasars may harbor black holes growing at an extraordinarily rapid rate. The current study and previous ones by different teams suggest that such quasars might have been more common in the early Universe, only about a billion years after the Big Bang. Such rapid growth might also explain the existence of huge black holes at even earlier times.

    A paper describing these results appears in an upcoming issue of The Astrophysical Journal and is available online.

    Read More from NASA’s Chandra X-ray Observatory

    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 9:06 am on April 21, 2015 Permalink | Reply
    Tags: , , Dartmouth College, , Supermassive Black Holes   

    From Dartmouth College via phys.org: “Black hole hunters tackle a cosmic conundrum” 

    physdotorg
    phys.org

    1
    Dartmouth

    April 20, 2015
    No Writer Credit

    2
    A Hubble Space Telescope image shows the Henize 2-10 galaxy, with a hidden supermassive black hole at its center. Credit: NASA

    NASA Hubble Telescope
    NASA/ESA Hubble

    Dartmouth astrophysicists and their colleagues have not only proven that a supermassive black hole exists in a place where it isn’t supposed to be, but in doing so have opened a new door to what things were like in the early universe.

    Henize 2-10 is a small irregular galaxy that is not too far away in astronomical terms—30 million light-years. “This is a dwarf starburst galaxy—a small galaxy with regions of very rapid star formation—about 10 percent of the size of our own Milky Way,” says co-author Ryan Hickox, an assistant professor in Dartmouth’s Department of Physics and Astronomy. “If you look at it, it’s a blob, but it surprisingly harbors a central black hole.”

    Hickox says there may be similar small galaxies in the known universe, but this is one of the only ones close enough to allow detailed study. Lead author Thomas Whalen, Hickox and a team of other researchers have now analyzed a series of four X-ray observations of Henize 2-10 using three space telescopes over 13 years, providing conclusive evidence for the existence of a black hole.

    Their findings appear as an online preprint to be published in The Astrophysical Journal Letters. A PDF also is available on request.

    Suspicions about Henize 2-10 first arose in 2011 when another team, that included some of the co-authors, first looked at galaxy Henize 2-10 and tried to explain its behavior. The observed dual emissions of X-ray and radio waves, often associated with a black hole, gave credence to the presence of one. The instruments utilized were Japan’s Advanced Satellite for Cosmology and Astrophysics (1997), the European Space Agency’s XMM-Newton (2004, 2011) and NASA’s Chandra X-ray Observatory (2001).

    JAXA ASCA ASTRO-D satellite
    JAXA/ASCA

    ESA XMM Newton
    ESA/XMM-Newton

    NASA Chandra Telescope
    NASA/Chandra

    “The galaxy was bright in 2001, but it has gotten less bright over time,” says Hickox. “This is not consistent with being powered only by star formation processes, so it almost certainly had to have a small supermassive black hole—small compared to the largest supermassive black holes in massive elliptical galaxies, but is still a million times the mass of the sun.”

    A characteristic of supermassive black holes is that they do change with time—not a huge amount, explains Hickox, “and that is exactly what Tom Whalen found,” he says. “This variability definitely tells us that the emission is coming from a compact source at the center of this system, consistent with it being a supermassive black hole.”

    While supermassive black holes are typically found in the central bulges of galaxies, Henize 2-10 has no bulge. “All the associations that people have made between galaxies and black holes tell us there ought to be no black hole in this system,” says Whalen, but the team has proven otherwise. Whalen, a recent Dartmouth graduate, is now a member of the Chandra X-ray Center team at the Harvard-Smithsonian Center for Astrophysics.

    A big question is where black holes come from. “When people try to simulate where the galaxies come from, you have to put in these black holes at the beginning, but we don’t really know what the conditions were. These dwarf starburst galaxies are the closest analogs we have in the universe around us now, to the first galaxies early in the universe,” says Whalen.

    The authors conclude: “Our results confirm that nearby star-forming galaxies can indeed form massive black holes and that by implication so can their primordial counterparts.”

    “Studying those to get some sense of what might have happened very early in the universe is very powerful,” says Hickox.

    See the full article here.

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 1:32 pm on April 16, 2015 Permalink | Reply
    Tags: , , , , Supermassive Black Holes   

    From ALMA: “ALMA Reveals Intense Magnetic Field Close to Supermassive Black Hole” 

    ESO ALMA Array
    ALMA

    16 April 2015
    Valeria Foncea
    Education and Public Outreach Officer
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 467 6258
    Cell: +56 9 75871963
    Email: vfoncea@alma.cl

    Richard Hook
    Public Information Officer, ESO
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 434.242.9559
    E-mail: cblue@nrao.edu

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory Tokyo, Japan
    Tel: +81 422 34 3630
    E-mail: hiramatsu.masaaki@nao.ac.jp

    1
    This artist’s impression shows the surroundings of a supermassive black hole, typical of that found at the heart of many galaxies. The black hole itself is surrounded by a brilliant accretion disc of very hot, infalling material and, further out, a dusty torus. There are also often high-speed jets of material ejected at the black hole’s poles that can extend huge distances into space. Observations with ALMA have detected a very strong magnetic field close to the black hole at the base of the jets and this is probably involved in jet production and collimation.

    The Atacama Large Millimeter/submillimeter Array (ALMA) has revealed an extremely powerful magnetic field, beyond anything previously detected in the core of a galaxy, very close to the event horizon of a supermassive black hole. This new observation helps astronomers to understand the structure and formation of these massive inhabitants of the centres of galaxies, and the twin high-speed jets of plasma they frequently eject from their poles. The results appear in the 17 April 2015 issue of the journal Science.

    Supermassive black holes, often with masses billions of times that of the Sun, are located at the heart of almost all galaxies in the Universe. These black holes can accrete huge amounts of matter in the form of a surrounding disc. While most of this matter is fed into the black hole, some can escape moments before capture and be flung out into space at close to the speed of light as part of a jet of plasma. How this happens is not well understood, although it is thought that strong magnetic fields, acting very close to the event horizon, play a crucial part in this process, helping the matter to escape from the gaping jaws of darkness.

    Up to now only weak magnetic fields far from black holes — several light-years away — had been probed [1]. In this study, however, astronomers from Chalmers University of Technology and Onsala Space Observatory in Sweden have now used ALMA to detect signals directly related to a strong magnetic field very close to the event horizon of the supermassive black hole in a distant galaxy named PKS 1830-211. This magnetic field is located precisely at the place where matter is suddenly boosted away from the black hole in the form of a jet.

    The team measured the strength of the magnetic field by studying the way in which light was polarised, as it moved away from the black hole.

    “Polarisation is an important property of light and is much used in daily life, for example in sun glasses or 3D glasses at the cinema,” says Ivan Marti-Vidal, lead author of this work. “When produced naturally, polarisation can be used to measure magnetic fields, since light changes its polarisation when it travels through a magnetised medium. In this case, the light that we detected with ALMA had been travelling through material very close to the black hole, a place full of highly magnetised plasma.”

    The astronomers applied a new analysis technique that they had developed to the ALMA data and found that the direction of polarisation of the radiation coming from the centre of PKS 1830-211 had rotated [2]. These are the shortest wavelengths ever used in this kind of study, which allow the regions very close to the central black hole to be probed [3].

    “We have found clear signals of polarisation rotation that are hundreds of times higher than the highest ever found in the Universe,” says Sebastien Muller, co-author of the paper. “Our discovery is a giant leap in terms of observing frequency, thanks to the use of ALMA, and in terms of distance to the black hole where the magnetic field has been probed — of the order of only a few light-days from the event horizon. These results, and future studies, will help us understand what is really going on in the immediate vicinity of supermassive black holes.”

    Notes

    [1] Much weaker magnetic fields have been detected in the vicinity of the relatively inactive supermassive black hole at the centre of the Milky Way. Recent observations have also revealed weak magnetic fields in the active galaxy NGC 1275, which were detected at millimetre wavelengths.

    [2] Magnetic fields introduce Faraday rotation, which makes the polarisation rotate in different ways at different wavelengths. The way in which this rotation depends on the wavelength tells us about the magnetic field in the region.

    [3] The ALMA observations were at an effective wavelength of about 0.3 millimetres, earlier investigations were at much longer radio wavelengths. Only light of millimetre wavelengths can escape from the region very close to the black hole, longer wavelength radiation is absorbed.

    More Information

    This research was presented in a paper entitled “A strong magnetic field in the jet base of a supermassive black hole” to appear in Science on 16 April 2015.

    The team is composed of I. Martí-Vidal (Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, Onsala, Sweden), S. Muller (Onsala Space Observatory), W. Vlemmings (Onsala Space Observatory), C. Horellou (Onsala Space Observatory), S. Aalto (Onsala Space Observatory).

    See the full article here.

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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