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  • richardmitnick 9:06 pm on November 26, 2015 Permalink | Reply
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    From ICRAR: “Scientists spot jets from supermassive black hole snacking on a star” 

    International Center for Radio Astronomy Research

    International Centre for Radio Astronomy Research

    27 November, 2015

    Dr Gemma Anderson
    ICRAR – Curtin University
    Ph: +61 8 9266 3577
    M: +61 408 955 483
    E: Gemma.Anderson@icrar.org

    Dr James Miller-Jones
    ICRAR – Curtin University
    Ph: +61 8 9266 3785
    M: +61 488 484 825
    E: James.Miller-Jones@icrar.org

    Pete Wheeler
    Media Contact
    M: +61 423 982 018
    E: Pete.Wheeler@icrar.org

    An artist’s impression of a star being drawn toward a black hole and destroyed, triggering a jet of plasma made from debris left over from the stars destruction.
    Credit: Modified from an original image by Amadeo Bachar.

    Scientists have discovered a hungry black hole swallowing a star at the centre of a nearby galaxy.

    The supermassive black hole was found to have faint jets of material shooting out from it and helps to confirm scientists’ theories about the nature of black holes.

    The discovery was published today in the journal Science.

    Astrophysicist Dr Gemma Anderson, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said a supermassive black hole swallowing a star is an extreme event in which the star gets ripped apart.

    “It’s very unusual when a supermassive black hole at the centre of a galaxy actually eats a star, we’ve probably only seen about 20 of them,” she said.

    “Everything we know about black holes suggests we should see a jet when this happens but until now they’ve only been detected in a few of the most powerful systems.

    “Now we’ve finally found one in a more normal event.”

    The discovery is the first time scientists have been able to see both a disk of material falling into a black hole, known as an accretion disk, and a jet in a system of this kind.

    ICRAR astrophysicist Dr James Miller-Jones compared the energy produced by the jets in this event to the entire energy output of the Sun over 10 million years.

    He said it was likely all supermassive black holes swallowing stars launched jets but this discovery was made because the black hole is relatively close to Earth and was studied soon after it was first seen.

    The black hole is only 300 million light years away from us and the team (led by Dr Sjoert van Velzen from The Johns Hopkins University in the USA) were able to make their first observations only three weeks after it was found.

    “We’ve shown that it was just a question of looking at the right time and with enough sensitivity,” Dr Miller-Jones said.

    “Then you can show that a jet exists right at the point you think it should.”

    Dr Anderson began the research while working with the 4 PI SKY team at Oxford University but moved to Western Australia in September.

    She said the event was first picked up by the All-sky Automated Survey for Supernovae (ASAS-SN), which is pronounced ‘assassin’ by astronomers, and followed up with the Arcminute Microkelvin Imager (AMI), a radio telescope, located near Cambridge.

    Arcminute Microkelvin Imager
    Arcminute Microkelvin Imager (AMI) Small Array

    “Hopefully with the increased sensitivity of future telescopes like the Square Kilometre Array we’ll be able to detect jets from other supermassive black holes of this type and discover even more about them,” Dr Anderson said.

    Further information:
    For more information about the 4 PI SKY project visit http://www.4pisky.org

    ICRAR is a joint venture between Curtin University and The University of Western Australia with support and funding from the State Government of Western Australia.

    Original publication details:

    ‘A radio jet from the optical and X-ray bright stellar tidal disruption flare ASASSN-14li’ published in the journal Science on 26/11/2015. A copy of the paper is available upon request. ​

    See the full article here .

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    ICRAR is an equal joint venture between Curtin University and The University of Western Australia with funding support from the State Government of Western Australia. The Centre’s headquarters are located at UWA, with research nodes at both UWA and the Curtin Institute for Radio Astronomy (CIRA).
    ICRAR has strong support from the government of Australia and is working closely with industry and the astronomy community, including CSIRO and the Australian Telescope National Facility, iVEC, and the international SKA Project Office (SPO), based in the UK.

    ICRAR is:

    Playing a key role in the international Square Kilometre Array (SKA) project, the world’s biggest ground-based telescope array.

    SKA Square Kilometer Array
    Attracting some of the world’s leading researchers in radio astronomy, who will also contribute to national and international scientific and technical programs for SKA and ASKAP.
    Creating a collaborative environment for scientists and engineers to engage and work with industry to produce studies, prototypes and systems linked to the overall scientific success of the SKA, MWA and ASKAP.

    SKA Murchison Widefield Array
    A Small part of the Murchison Widefield Array

    Enhancing Australia’s position in the international SKA program by contributing to the development process for the SKA in scientific, technological and operational areas.
    Promoting scientific, technical, commercial and educational opportunities through public outreach, educational material, training students and collaborative developments with national and international educational organisations.
    Establishing and maintaining a pool of emerging and top-level scientists and technologists in the disciplines related to radio astronomy through appointments and training.
    Making world-class contributions to SKA science, with emphasis on the signature science themes associated with surveys for neutral hydrogen and variable (transient) radio sources.
    Making world-class contributions to SKA capability with respect to developments in the areas of Data Intensive Science and support for the Murchison Radio-astronomy Observatory.

  • richardmitnick 2:17 pm on November 20, 2015 Permalink | Reply
    Tags: AGN's, , , , Supermassive Black Holes   

    From Nautilus: “This Is Why It’s Hard to Recognize a Black Hole” 



    Nov 18, 2015
    Summer Ash

    Black Beauty: The supermassive black hole at the center of this galaxy, around 11 million light years away toward the constellation Centaurus, is currently classified as a quasar. It is roughly 55 million times more massive than our Sun. Its collimated jets, in blue, surpass the diameter of the entire galaxy, extending up to 13,000 light years. The Milky Way, by comparison, is roughly ten times this length. NASA/CXC/CfA/R.Kraft et al.; MPIfR/ESO/APEX/A.Weiss et al.; ESO/WFI.

    Astronomers can sometimes be literal to a fault. We like to call things as we see them. For example, if it’s red and it’s huge: Red Giant. White and small: White Dwarf. Massive explosion: Big Bang. Dark and sucks everything in: Black Hole. Most of the time, classifying objects this way works fine—either it’s new, or it’s something we already know of. But sometimes, as with Pluto, we make new observations that force us to question the name, reassess the object, and identify it differently. You might think this never happens with something as clearly defined as a black hole, but you’d be wrong.

    Though we can’t observe them directly, we can see how the two types of black holes—stellar mass and supermassive—affect their surroundings. Stellar mass black holes, the product of a dying star going supernova and collapsing on itself, are the more familiar, predicted nearly a century ago by [Albert] Einstein’s theory of general relativity; They usually only affect the behavior of the nearest star or two. Supermassive black holes, on the other hand, are over a million times more massive. We still don’t know how these form, but we believe they exist at the center of almost every galaxy, sometimes having the power to alter the appearance of their entire galaxy.

    This capacity for mass distortion makes characterizing supermassive black holes particularly tricky.

    As the stars, gas, and dust in the center of a galaxy get closer and closer to a supermassive black hole, they get packed tighter and tighter into a smaller and smaller space, heating up until, at a critical distance, everything is ripped apart, reduced to atomic particles. When we spot supermassive black holes, it’s this heat radiating away from the orbiting debris—known as an accretion disk—that we actually see, not the black hole itself. Some supermassive black holes “eat” more than others and, in the process, give off significantly more light than their less active brethren. These active galactic nuclei, or AGN for short, are some of the most powerful, most energetic forces in the Universe. Not only do they give off heat, they also often eject material in the form of collimated (beamed) jets, perpendicular to the plane of the disk, which blast their way out of the galaxy’s core—dwarfing in size not just the accretion disk, but also the galaxy itself. What’s more, some AGN have a dusty torus, the geometric equivalent of a donut, in the same plane as their accretion disk, but much, much bigger and thicker. So thick, in fact, that if you looked at them from the side, you wouldn’t see the disk at all, much less the black hole in the center (as seen in the image above).

    Despite having this standard model of an AGN—a supermassive black hole surrounded by an accretion disk with jets streaming out in opposite directions, all encompassed by a dusty torus—making sense of our observations is still a challenge: The light we see doesn’t always paint the same picture. Sometimes we see jets, sometimes we don’t. Sometimes we see the torus, sometimes we don’t. Sometimes we see light so concentrated and bright that we can’t even tell if there’s a galaxy there at all. We label these sightings accordingly: AGN at great distances with cores so bright, they outshine all their stars in optical light, are called quasars (for “quasi-stellar”), like the one pictured above; AGN that glow strongly in the infrared are called Seyferts, after the astronomer Carl Seyfert, who first identified them in 1943; And AGN, with cores and jets whose emitted light dominates in the radio spectrum, are called radio galaxies.

    Resembling a swirling witch’s cauldron of glowing vapors, the black hole-powered core of a nearby active galaxy appears in this colorful NASA Hubble Space Telescope image. The galaxy lies 13 million light-years away in the southern constellation Circinus.
    This galaxy is designated a type 2 Seyfert, a class of mostly spiral galaxies that have compact centers and are believed to contain massive black holes. Seyfert galaxies are themselves part of a larger class of objects called Active Galactic Nuclei or AGN. AGN have the ability to remove gas from the centers of their galaxies by blowing it out into space at phenomenal speeds. Astronomers studying the Circinus galaxy are seeing evidence of a powerful AGN at the center of this galaxy as well.
    Much of the gas in the disk of the Circinus spiral is concentrated in two specific rings — a larger one of diameter 1,300 light-years, which has already been observed by ground-based telescopes, and a previously unseen ring of diameter 260 light-years.
    In the Hubble image, the smaller inner ring is located on the inside of the green disk. The larger outer ring extends off the image and is in the plane of the galaxy’s disk. Both rings are home to large amounts of gas and dust as well as areas of major “starburst” activity, where new stars are rapidly forming on timescales of 40 – 150 million years, much shorter than the age of the entire galaxy.
    At the center of the starburst rings is the Seyfert nucleus, the believed signature of a supermassive black hole that is accreting surrounding gas and dust. The black hole and its accretion disk are expelling gas out of the galaxy’s disk and into its halo (the region above and below the disk). The detailed structure of this gas is seen as magenta-colored streamers extending towards the top of the image.
    In the center of the galaxy and within the inner starburst ring is a V-shaped structure of gas. The structure appears whitish-pink in this composite image, made up of four filters. Two filters capture the narrow lines from atomic transitions in oxygen and hydrogen; two wider filters detect green and near-infrared light. In the narrow-band filters, the V-shaped structure is very pronounced. This region, which is the projection of a three-dimensional cone extending from the nucleus to the galaxy’s halo, contains gas that has been heated by radiation emitted by the accreting black hole. A “counter-cone,” believed to be present, is obscured from view by dust in the galaxy’s disk. Ultraviolet radiation emerging from the central source excites nearby gas causing it to glow. The excited gas is beamed into the oppositely directed cones like two giant searchlights.
    Located near the plane of our own Milky Way Galaxy, the Circinus galaxy is partially hidden by intervening dust along our line of sight. As a result, the galaxy went unnoticed until about 25 years ago. This Hubble image was taken on April 10, 1999 with the Wide Field Planetary Camera 2.
    The research team, led by Andrew S. Wilson of the University of Maryland, is using these visible light images along with near-infrared data to further understand the dynamics of this powerful galaxy.
    Date 10 April 1999

    If they are all fueled by supermassive black holes, why don’t all AGN look the same? One reason could be our point of view. The theory of AGN unification posits that all AGN have the same basic building blocks (accretion disk, jets, torus); The striking differences we observe, according to this theory, are all due to their orientation in space.

    Here on Earth, we only have one vantage point from which to observe the cosmos. We see galaxies randomly distributed around us, some of them edge-on, some of them face-on, and the rest at all the angles in-between. We cannot fly around to look at these galaxies from any other angle than the one they present to us. But with the advent of supercomputers, we can now simulate these galaxies better than ever before and virtually fly around them as much as we like, enjoying the sights from any angle. We can take an AGN and turn it so we’re looking straight down one of the jets, towards the galactic core, making it resemble a blazar, sort of a blazing quasar. Start tilting the AGN until the jet is rotated ninety degrees away from us, and it appears to morph from a blazar to a quasar to, finally, a Seyfert.

    Yet AGN unification is far from a settled problem in astrophysics. There could be other factors at play than just our point of view, like physical processes in and around black holes we don’t fully understand or measurements we haven’t thought to take. As we build better telescopes and amass new data, we can only hope that we’ll see these active galactic nuclei for what they really are. Otherwise, we might need a lot more names.

    See the full article here .

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

  • richardmitnick 1:17 pm on October 27, 2015 Permalink | Reply
    Tags: , , Supermassive Black Holes   

    From JPL-Caltech: “Black Hole Has Major Flare” 


    October 27, 2015
    Whitney Clavin
    Jet Propulsion Laboratory, Pasadena, California


    The baffling and strange behaviors of black holes have become somewhat less mysterious recently, with new observations from NASA’s Explorer missions Swift and the Nuclear Spectroscopic Telescope Array, or NuSTAR.

    NASA SWIFT Telescope


    The two space telescopes caught a supermassive black hole in the midst of a giant eruption of X-ray light, helping astronomers address an ongoing puzzle: How do supermassive black holes flare?

    The results suggest that supermassive black holes send out beams of X-rays when their surrounding coronas — sources of extremely energetic particles — shoot, or launch, away from the black holes.

    “This is the first time we have been able to link the launching of the corona to a flare,” said Dan Wilkins of Saint Mary’s University in Halifax, Canada, lead author of a new paper on the results appearing in the Monthly Notices of the Royal Astronomical Society. “This will help us understand how supermassive black holes power some of the brightest objects in the universe.”

    Supermassive black holes don’t give off any light themselves, but they are often encircled by disks of hot, glowing material. The gravity of a black hole pulls swirling gas into it, heating this material and causing it to shine with different types of light. Another source of radiation near a black hole is the corona. Coronas are made up of highly energetic particles that generate X-ray light, but details about their appearance, and how they form, are unclear.

    Astronomers think coronas have one of two likely configurations. The “lamppost” model says they are compact sources of light, similar to light bulbs, that sit above and below the black hole, along its rotation axis. The other model proposes that the coronas are spread out more diffusely, either as a larger cloud around the black hole, or as a “sandwich” that envelops the surrounding disk of material like slices of bread. In fact, it’s possible that coronas switch between both the lamppost and sandwich configurations.

    The new data support the “lamppost” model — and demonstrate, in the finest detail yet, how the light-bulb-like coronas move. The observations began when Swift, which monitors the sky for cosmic outbursts of X-rays and gamma rays, caught a large flare coming from the supermassive black hole called Markarian 335, or Mrk 335, located 324 million light-years away in the direction of the constellation Pegasus. This supermassive black hole, which sits at the center of a galaxy, was once one of the brightest X-ray sources in the sky.

    “Something very strange happened in 2007, when Mrk 335 faded by a factor of 30. What we have found is that it continues to erupt in flares but has not reached the brightness levels and stability seen before,” said Luigi Gallo, the principal investigator for the project at Saint Mary’s University. Another co-author, Dirk Grupe of Morehead State University in Kentucky, has been using Swift to regularly monitor the black hole since 2007.

    In September 2014, Swift caught Mrk 335 in a huge flare. Once Gallo found out, he sent a request to the NuSTAR team to quickly follow up on the object as part of a “target of opportunity” program, where the observatory’s previously planned observing schedule is interrupted for important events. Eight days later, NuSTAR set its X-ray eyes on the target, witnessing the final half of the flare event.

    After careful scrutiny of the data, the astronomers realized they were seeing the ejection, and eventual collapse, of the black hole’s corona.

    “The corona gathered inward at first and then launched upwards like a jet,” said Wilkins. “We still don’t know how jets in black holes form, but it’s an exciting possibility that this black hole’s corona was beginning to form the base of a jet before it collapsed.”

    How could the researchers tell the corona moved? The corona gives off X-ray light that has a slightly different spectrum — X-ray “colors” — than the light coming from the disk around the black hole. By analyzing a spectrum of X-ray light from Mrk 335 across a range of wavelengths observed by both Swift and NuSTAR, the researchers could tell that the corona X-ray light had brightened — and that this brightening was due to the motion of the corona.

    Coronas can move very fast. The corona associated with Mrk 335, according to the scientists, was traveling at about 20 percent the speed of light. When this happens, and the corona launches in our direction, its light is brightened in an effect called relativistic Doppler boosting.

    Putting this all together, the results show that the X-ray flare from this black hole was caused by the ejected corona.

    “The nature of the energetic source of X-rays we call the corona is mysterious, but now with the ability to see dramatic changes like this we are getting clues about its size and structure,” said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology in Pasadena, who was not affiliated with the study.

    Many other black hole brainteasers remain. For example, astronomers want to understand what causes the ejection of the corona in the first place.

    NuSTAR is a Small Explorer mission led by Caltech and managed by NASA’s Jet Propulsion Laboratory in Pasadena, California, for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.

    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 [1], 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 2:37 pm on October 10, 2015 Permalink | Reply
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    From RAS: “Universe’s hidden supermassive black holes revealed” From July but Well Worth Your Time 

    Royal Astronomical Society

    Royal Astronomical Society

    09 July 2015
    Dr Robert Massey
    Royal Astronomical Society
    Mob: +44 (0)794 124 8035

    Ms Anita Heward
    Royal Astronomical Society
    Mob: +44 (0)7756 034 243

    Dr Sam Lindsay
    Royal Astronomical Society
    Mob: +44 (0)7957 566 861

    Durham University Marketing and Communications Office
    Tel: +44 (0)191 334 6075

    Astronomers have found evidence for a large population of hidden supermassive black holes in the Universe. Using NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) satellite observatory, the team of international scientists detected the high-energy x-rays from five supermassive black holes previously clouded from direct view by dust and gas. The findings were presented today at the Royal Astronomical Society’s National Astronomy Meeting, at Venue Cymru, in Llandudno, Wales (Monday 6 July).

    NASA/Nu-STAR Credit: NASA/JPL-Caltech.

    The research, led by astronomers at Durham University, UK, supports the theory that potentially millions more supermassive black holes exist in the Universe, but are hidden from view.

    The scientists pointed NuSTAR at nine candidate hidden supermassive black holes that were thought to be extremely active at the centre of galaxies, but where the full extent of this activity was potentially obscured from view.

    High-energy x-rays found for five of the black holes confirmed that they had been hidden by dust and gas. The five were much brighter and more active than previously thought as they rapidly feasted on surrounding material and emitted large amounts of radiation.

    A Hubble Space Telescope colour image of one of the nine galaxies targeted by NuSTAR. The high energy X-rays detected by NuSTAR revealed the presence of an extremely active supermassive black hole at the galaxy centre, deeply buried under a blanket of gas and dust. Credit: Hubble Legacy Archive, NASA, ESA.

    NASA Hubble Telescope
    NASA/ESA Hubble

    Such observations were not possible before NuSTAR, which launched in 2012 and is able to detect much higher energy x-rays than previous satellite observatories.

    Lead author George Lansbury, a postgraduate student in the Centre for Extragalactic Astronomy, at Durham University, said: “For a long time we have known about supermassive black holes that are not obscured by dust and gas, but we suspected that many more were hidden from our view.

    “Thanks to NuSTAR for the first time we have been able to clearly see these hidden monsters that are predicted to be there, but have previously been elusive because of their ‘buried’ state.

    “Although we have only detected five of these hidden supermassive black holes, when we extrapolate our results across the whole Universe then the predicted numbers are huge and in agreement with what we would expect to see.”

    Daniel Stern, the project scientist for NuSTAR at NASA’s Jet Propulsion Laboratory in Pasadena, California, added: “High-energy X-rays are more penetrating than low-energy X-rays, so we can see deeper into the gas burying the black holes. NuSTAR allows us to see how big the hidden monsters are and is helping us learn why only some black holes appear obscured.”

    The research was funded by the Science and Technology Facilities Council (STFC) and has been accepted for publication in The Astrophysical Journal.

    An artist’s illustration of a supermassive black hole, actively feasting on its surroundings. The central black hole is hidden from direct view by a thick layer of encircling gas and dust.

    See the full article here .

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  • richardmitnick 7:48 am on October 5, 2015 Permalink | Reply
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    From COSMOS: “Einstein’s gravitational waves remain elusive” 

    Cosmos Magazine bloc


    5 Oct 2015
    Alan Duffy

    Could the cataclysmic coming-together of two black holes produce fewer ripples in spacetime than we thought?

    The cosmic do-si-do of two supermassive black holes spiralling towards each other is a cataclysmic dance of such intensity, it should ripple the fabric of spacetime itself – or so says [Albert] Einstein’s general theory of relativity. One hundred years have passed since Einstein first proposed the existence of gravitational waves, but they are yet to be detected directly.

    Artist concept of Gravity Probe B orbiting the Earth to measure space-time, a four-dimensional description of the universe including height, width, length, and time.

    NASA Gravity Probe B
    NASA/Gravity Probe B

    Astronomers in Australia have spent the past decade conducting the most thorough search yet for gravitational waves released when supermassive black holes circle each other, using the Parkes radio telescope in New South Wales. But as the researchers reported in Science in September, they could find no trace of them.

    Could Einstein be wrong? Or have we misunderstood black holes?

    The Parkes radio telescope in NSW conducted an exhaustive but unsuccessful search for gravitational waves. Credit: CSIRO, Shaun Amy/getty images

    Space must be awash with gravitational waves but they’re extraordinarily weak. If a gravitational wave were to pass through you now, this ripple in spacetime would stretch you taller and thinner, then squash you shorter and fatter. The reason you wouldn’t notice is because your height would be altered by less than the width of a proton (a fraction of the size of an atom).

    CSIRO astronomer Ryan Shannon and his team attempted to detect gravitational waves from black holes by measuring their effect on the pulses of radio waves coming from a neutron star more than 3,600 million billion metres away.

    Neutron stars (another prediction of Einstein’s) were discovered in 1967. They are the crushed cores of large dead stars that, when they ran out of fuel, collapsed under their own immense gravity, squeezing as much mass as our Sun’s into the size of Sydney’s central business district.

    And like an ice-skater who spins faster when she tucks her arms in, a neutron star rotates more rapidly as it collapses. As they spin, some emit a tightly focused beam of radiation that shines like a lighthouse. If the Earth lies in the rotating beams’ path, we detect this radiation as the pulses of radio waves, which earned these neutron stars the nickname pulsars.

    A pulsar is the astronomical equivalent of a lighthouse.CREDIT: CAASTRO
    Download mp4 video here.

    A pulsar’s spin is so stable that the pulse it emits is as reliable as the super-accurate tick of an astronomical clock.

    Over the past 11 years the CSIRO’s Parkes radio telescope has been timing the pulses from one such regular and bright pulsar. It spins at more than 300 rotations per second, and each of its 115,836,854,515 rotations over more than a decade has been right on time. But according to Einstein, this shouldn’t be the case.

    According to Einstein’s theory, the gravitational ripples emitted by countless pairs of circling black holes around the Universe should add up, sometimes stretching spacetime between Earth and the pulsar by 10 metres. This stretch should skew the arrival time of pulses from the pulsar by up to one ten-billionth of a second. The Parkes telescope’s timing equipment is accurate enough to detect such a minute change.

    But it didn’t detect any delay.

    As two black holes circle each other, gravitational waves ripple out around them. CREDIT: CAASTRO
    Download mp4 video here.

    The researchers didn’t doubt that gravitational waves exist. They have been detected indirectly. American astronomers Russell Hulse and Joseph Taylor won the 1993 physics Nobel Prize for doing this. They used a pair of neutron stars to measure the astoundingly tiny shortening of the stars’ year – about 30 seconds over three decades – as they spiralled inwards toward each other. Hulse and Taylor calculated that this amount of shortening followed Einstein’s predictions. Some of the energy that kept the stars rotating must have been emitted in the form of gravitational waves.

    So the more likely explanation for the failure of the Parkes research is that we don’t fully understand the black hole mergers that generate gravitational waves.

    Recent observations suggest every galaxy, including our own Milky Way, harbours a supermassive black hole at its core. For reasons still unclear, the mass of the black hole is directly related to the mass of its galaxy – in nearby galaxies where we have been able to make these measurements, at least.

    More distant black holes, which formed earlier, may be smaller than those in nearby galaxies. If so, the spacetime ripples produced as older, more distant black holes meet and begin spiralling in toward each other may be too small for Parkes to pick up – even if there are billions of them.

    Alternatively, early galaxies tend to be more gas-rich. This gas would act like treacle, slowing black holes down. Instead of dancing around each other for billions of years, they “fall in” toward each other much faster, creating a short sharp blast, but ultimately fewer gravitational waves.

    All of which gives Shannon and his team plenty to ponder as they continue their search. Measuring gravitational waves directly would do more than confirm Einstein’s theory of general relativity. It would also be the first time astronomers have looked into the Universe with something other than light. All telescopes, regardless of their size and sophistication, use light waves (be they the long wavelength radio wave variety, visible light, or short wavelength X-rays).

    The observation of gravitational waves would be the dawn of a new era of astronomy. Humanity would look outwards with gravity, and who knows what we might see.

    See the full article here .

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  • richardmitnick 11:33 am on September 24, 2015 Permalink | Reply
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    From phys.org: “Black hole is 30 times expected size” 


    September 24, 2015

    A still frame from a movie, illustrating an active galactic nucleus, with jets of material flowing from out from a central black hole. Credit: NASA / Dana Berry / SkyWorks Digital

    The central supermassive black hole of a recently discovered galaxy is far larger than should be possible, according to current theories of galactic evolution. New work, carried out by astronomers at Keele University and the University of Central Lancashire, shows that the black hole is much more massive than it should be, compared to the mass of the galaxy around it. The scientists publish their results in a paper in Monthly Notices of the Royal Astronomical Society.

    The galaxy, SAGE0536AGN, was initially discovered with NASA’s Spitzer space telescope in infrared light.

    NASA Spitzer Telescope

    Thought to be at least 9 billion years old, it contains an active galactic nucleus (AGN), an incredibly bright object resulting from the accretion of gas by a central supermassive black hole. The gas is accelerated to high velocities due to the black hole’s immense gravitational field, causing this gas to emit light.

    The team has now also confirmed the presence of the black hole by measuring the speed of the gas moving around it. Using the Southern African Large Telescope [SALT], the scientists observed that an emission line of hydrogen in the galaxy spectrum (where light is dispersed into its different colours – a similar effect is seen using a prism) is broadened through the Doppler Effect, where the wavelength (colour) of light from objects is blue- or red-shifted depending on whether they are moving towards or away from us.

    SALT South African Large Telescope
    SALT South African Large Telescope Interior

    The degree of broadening implies that the gas is moving around at high speed, a result of the strong gravitational field of the black hole.

    These data have been used to calculate the black hole’s mass: the more massive the black hole, the broader the emission line. The black hole in SAGE0536AGN was found to be 350 million times the mass of the Sun. But the mass of the galaxy itself, obtained through measurements of the movement of its stars, has been calculated to be 25 billion solar masses. This is seventy times larger than that of the black hole, but the black hole is still thirty times larger than expected for this size of galaxy.

    “Galaxies have a vast mass, and so do the black holes in their cores. This one though is really too big for its boots – it simply shouldn’t be possible for it to be so large”, said Dr Jacco van Loon, an astrophysicist at Keele University and the lead author on the new paper.

    In ordinary galaxies the black hole would grow at the same rate as the galaxy, but in SAGE0536AGN the black hole has grown much faster, or the galaxy stopped growing prematurely. Because this galaxy was found by accident, there may be more such objects waiting to be discovered. Time will tell whether SAGE0536AGN really is an oddball, or simply the first in a new class of galaxies.

    See the full article here .

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  • richardmitnick 2:55 pm on September 23, 2015 Permalink | Reply
    Tags: , , , , Supermassive Black Holes   

    From AAS NOVA: ” Collapsing Enormous Stars” 


    Amercan Astronomical Society

    23 September 2015
    Susanna Kohler

    A scene from a computer animation of a star collapsing to form a gamma-ray burst. A recent study suggests such events could happen on a much larger scale in the distant universe. [NASA / SkyWorks Digital]

    One of the big puzzles in astrophysics is how supermassive black holes (SMBHs) managed to grow to the large sizes we’ve observed in the very early universe. In a recent study, a team of researchers examines the possibility that they were formed by the direct collapse of supermassive stars.

    Formation Mystery

    SMBHs billions of times as massive as the Sun have been observed at a time when the universe was less than a billion years old. But that’s not enough time for a stellar-mass black hole to grow to SMBH-size by accreting material — so another theory is needed to explain the presence of these monsters so early in the universe’s history. A new study, led by Tatsuya Matsumoto (Kyoto University, Japan), poses the following question: what if supermassive stars in the early universe collapsed directly into black holes?

    Previous studies of star formation in the early universe have suggested that, in the hot environment of these primordial times, stars might have been able to build up mass much faster than they can today. This could result in early supermassive stars roughly 100,000 times more massive than the Sun. But if these early stars end their lives by collapsing to become massive black holes — in the same way that we believe massive stars can collapse to form stellar-mass black holes today — this should result in enormously violent explosions. Matusmoto and collaborators set out to model this process, to determine what we would expect to see when it happens!

    Energetic Bursts

    The authors modeled the supermassive stars prior to collapse and then calculated whether a jet, created as the black hole grows at the center of the collapsing star, would be able to punch out of the stellar envelope. They demonstrated that the process would work much like the widely-accepted collapsar model of massive-star death, in which a jet successfully punches out of a collapsing star, violently releasing energy in the form of a long gamma-ray burst (GRB).

    Because the length of a long GRB is thought to be proportional to the free-fall timescale of the collapsing star, the collapse of these supermassive stars would create much longer GRBs than are typical of massive stars today. Instead of the typical long-GRB length of ~30 seconds, these ultra-long GRBs would be 104–106 seconds.

    Interestingly, we have already detected a small number of ultralong GRBs; they make up the tail end of the long GRB duration distribution. Could these detections be signals of collapsing supermassive stars in the early universe? According to the authors’ estimates, we could optimistically expect to detect roughly one of these events per year — so it’s entirely possible!

    Tatsuya Matsumoto et al 2015 ApJ 810 64. doi:10.1088/0004-637X/810/1/64

    See the full article here .

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  • richardmitnick 7:33 pm on September 21, 2015 Permalink | Reply
    Tags: , , Supermassive Black Holes   

    From Astronomy: “Pairs of galactic supermassive black holes five times rarer than previously thought” 

    Astronomy magazine

    Astronomy Magazine

    September 21, 2015
    NRAO, Socorro, New Mexico

    At left is the galaxy J0702+5002, which the researchers concluded is not an X-shaped galaxy whose form is caused by a merger. At right is the galaxy J1043+3131, which is a “true” candidate for a merged system. Roberts, et al., NRAO/AUI/NSF

    There may be fewer pairs of supermassive black holes orbiting each other at the cores of giant galaxies than previously thought, according to a new study by astronomers who analyzed data from the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) radio telescope.


    Massive galaxies harbor black holes with millions of times more mass than our Sun at their centers. When two such galaxies collide, their supermassive black holes join in a close orbital dance that ultimately results in the pair combining. That process, scientists expect, is the strongest source of the long-sought, elusive gravitational waves, still yet to be directly detected.

    “Gravitational waves represent the next great frontier in astrophysics, and their detection will lead to new insights on the universe,” said David Roberts of Brandeis University. “It’s important to have as much information as possible about the sources of these waves,” he added.

    Astronomers worldwide have begun programs to monitor fast-rotating pulsars throughout our Milky Way Galaxy in an attempt to detect gravitational waves. These programs seek to measure shifts in the signals from the pulsars caused by gravitational waves distorting the fabric of space-time. Pulsars are spinning superdense neutron stars that emit lighthouse-like beams of light and radio waves that allow precise measurement of their rotation rates.

    Roberts and his colleagues studied a sample of galaxies called X-shaped radio galaxies, whose peculiar structure indicated the possibility that the radio-emitting jets of superfast particles ejected by disks of material swirling around the central black holes of these galaxies have changed directions. The change, astronomers suggested, was caused by an earlier merger with another galaxy, causing the spin axis of the black hole as well as the jet axis to shift direction.

    Working from an earlier list of 100 such objects, they collected archival data from the VLA to make new, more detailed images of 52 of them. Their analysis of the new images led them to conclude that only 11 are “genuine” candidates for galaxies that have merged, causing their radio jets to change direction. The jet changes in the other galaxies, they concluded, came from other causes.

    Extrapolating from this result, the astronomers estimated that fewer than 1.3 percent of galaxies with extended radio emission have experienced mergers. This rate is five times lower than previous estimates.

    “This could significantly lower the level of very-long-wave gravitational waves coming from X-shaped radio galaxies, compared to earlier estimates,” Roberts said. “It will be very important to relate gravitational waves to objects we see through electromagnetic radiation, such as radio waves, in order to advance our understanding of fundamental physics.”

    Gravitational waves, ripples in space-time, were predicted in 1916 by Albert Einstein as part of his theory of general relativity. The first evidence for such waves came from observations of a pulsar orbiting another star, a system discovered in 1974 by Joseph Taylor and Russell Hulse. Observations of this pair over several years showed that their orbits are decaying at exactly the rate predicted by Einstein’s equations that indicate gravitational waves carrying energy away from the system.

    Taylor and Hulse received the 1993 Nobel Prize in physics for this work, which confirmed a predicted effect of gravitational waves. However, no direct detection of such waves has yet been made.

    Roberts worked with Jake Cohen and Jing Lu from Brandeis, who retrieved the data from the VLA archive and produced the images of the galaxies, and Lakshmi Saripalli and Ravi Subrahmanyan of the Raman research Institute in Bangalore, India.

    See the full article here .

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  • richardmitnick 5:14 pm on September 16, 2015 Permalink | Reply
    Tags: , , , Supermassive Black Holes   

    From Columbia: “New Support For Converging Black Holes” 

    Columbia U bloc

    Columbia University

    Sep 16 2015
    Kim Martineau

    Crash Expected in 100,000 Years – Far Sooner than Previously Predicted, Says Study

    Columbia researchers predict that a pair of converging supermassive black holes in the Virgo constellation will collide sooner than expected. Above, an artist’s conception of a merger. (P. Marenfeld/NOAO/AURA/NSF)

    Earlier this year, astronomers discovered what appeared to be a pair of supermassive black holes circling toward a collision so powerful it would send a burst of gravitational waves surging through the fabric of space-time itself.

    Now, in a new study in the journal Nature, astronomers at Columbia University provide additional evidence that a pair of closely orbiting black holes is causing the rhythmic flashes of light coming from quasar PG 1302-102.

    Based on calculations of the pair’s mass—together, and relative to each other—the researchers go on to predict a smashup 100,000 years from now, an impossibly long time to humans but the blink of an eye to a star or black hole. Spiraling together 3.5 billion light-years away, deep in the Virgo constellation, the pair is separated by a mere light-week. By contrast, the closest previously confirmed black hole pair is separated by 20 light-years.

    “This is the closest we’ve come to observing two black holes on their way to a massive collision,” said the study’s senior author, Zoltan Haiman, an astronomer at Columbia. “Watching this process reach its culmination can tell us whether black holes and galaxies grow at the same rate, and ultimately test a fundamental property of space-time: its ability to carry vibrations called gravitational waves, produced in the last, most violent, stage of the merger.”

    At the center of most giant galaxies, including our own Milky Way, lies a supermassive black hole so dense that not even light can escape. Over time, black holes grow bigger—millions to billions times more massive than the sun–by gobbling up stars, galaxies and even other black holes.

    A supermassive black hole about to cannibalize its own can be detected by the mysterious flickering of a quasar—the beacon of light produced by black holes as they burn through gas and dust swirling around them. Normally, quasars brighten and dim randomly, but when two black holes are on the verge of uniting, the quasar appears to flicker at regular intervals, like a light bulb on timer.

    Recently, a team led by Matthew Graham, a computational astronomer at the California Institute of Technology, designed an algorithm to pick out repeating light signals from 247,000 quasars monitored by telescopes in Arizona and Australia. Of the 20 pairs of black hole candidates discovered, they focused on the most compelling brightquasar– PG 1302-102. In a January study in Nature, they showed that PG 1302-102 appeared to brighten by 14 percent every five years, indicating the pair was less than a tenth of a light-year apart.

    Intrigued, Haiman and his colleagues wondered if they could build a theoretical model to explain the repeating signal. If the black holes were as close as predicted, one had to be circling a much larger counterpart at nearly a tenth ofthe speed of light, they hypothesized. At that speed, the smaller black hole would appear to brighten as it approached Earth’s line of sight under the relativistic Doppler beaming effect.

    If correct, they predicted they would find a five-year cycle in the quasar’s ultraviolet emissions—only two-and-a-half times more variable in its intensity. Analyzing UV observations collected by NASA’s Hubble and GALEX space telescopes they found exactly that.

    Previous explanations for the repeating signal include a warp in the debris disks orbiting the black holes, a wobble in the axis of one black hole and a lopsided debris disk formed as one black hole draws material off the other–all creating the impression of a periodic flicker from Earth.

    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 1:20 pm on September 4, 2015 Permalink | Reply
    Tags: , , Supermassive Black Holes, Tidal streams   

    From AAS: ” Don’t Cross the (Tidal) Streams” 


    Amercan Astronomical Society

    4 September 2015
    Susanna Kohler

    In this simulated TDE, a star is pulled apart by the tidal forces of a black hole. A recent study of the streams of stellar material in TDEs explains why we might be missing many of them. [NASA/S. Gezari (JHU)/J. Guillochon (UCSC)]

    In a tidal disruption event (TDE) ,an unfortunate star passes too close to a dormant supermassive black hole (BH) and gets torn apart by tidal forces, feeding the BH for a short time. Oddly, we’re not finding nearly as many TDEs — typically detected due to their distinctive observational signatures — as theory says we should. A recent study suggests that we might be missing many of these events, due to the way the streams of shredded stars fall onto the BHs.

    Signatures of Shredding

    When a BH tears a star apart, the star’s material is stretched out into what’s known as a tidal stream. That stream continues on a trajectory around the BH, with roughly half the material eventually falling back on the BH, whipping around it in a series of orbits. Where those orbits intersect each other, the material smashes together and circularizes, forming a disk that then accretes onto the BH.

    What does a TDE look like? We don’t observe anything until after the tidal streams collide and the material begins to accrete onto the BH. At that point we observe a sudden peak in luminosity, which then gradually decreases (scaling roughly as time-5/3) as the tail end of what’s left of the star accretes and the BH’s food source eventually runs out.

    So why have we only been observing about a tenth as many TDEs as theory predicts we should see? By studying the structure of tidal streams in TDEs, James Guillochon (Harvard-Smithsonian Center for Astrophysics) and Enrico Ramirez-Ruiz (UC Santa Cruz) have found a potential reason — and the culprit is general relativity.

    Dark Years

    The authors run a series of simulations of TDEs around black holes of varying masses and spins to see what form the resulting tidal streams take over time. They find that precession of the tidal stream due to the BH’s gravitational effects changes how the stream interacts with itself, and therefore what we observe. Some cases behave like what we expect for what’s currently considered a “typical” TDE — but some don’t.

    For cases where the relativistic effects are small (such as BHs with masses less than a few 106 solar masses), the tidal stream collides with itself after only a few windings around the BH, quickly forming a disk. The disk forms far from the BH, however, so it takes a long time to accrete. As a result, the observed flare can take 100 times longer to peak than what’s typically expected for a TDE, so we might be failing to identify these sources as TDEs.

    Furthermore, for cases where the BH is both massive and has a spin of a ≳ 0.2, the tidal stream doesn’t collide with itself right away. Instead, it can take many windings around the BH before the first intersection. In these cases, it may potentially be years after a star gets ripped apart before the material accretes and we’re able to observe the event!


    James Guillochon and Enrico Ramirez-Ruiz 2015 ApJ 809 166. doi:10.1088/0004-637X/809/2/166

    See the full article here.

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