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  • richardmitnick 2:13 pm on October 5, 2016 Permalink | Reply
    Tags: , , Black Holes, , , XJ1417+52: X-ray Telescopes Find Evidence for Wandering Black Hole   

    From Chandra: “XJ1417+52: X-ray Telescopes Find Evidence for Wandering Black Hole” 

    NASA Chandra Banner

    NASA Chandra Telescope

    NASA Chandra

    October 5, 2016

    Credit X-ray: NASA/CXC/UNH/D.Lin et al; Optical: NASA/STScI

    A “wandering” black hole has been found in the outer regions of a galaxy about 4.5 billion light years from Earth.

    Evidence suggests this newly discovered black hole has about 100,000 times the Sun’s mass, and was originally located in a smaller galaxy that merged with a larger one.

    Chandra data show this object gave off a tremendous amount of X-rays, which classifies it as a “hyperluminous X-ray source”.

    The burst of X-rays may have come from a star that was torn apart by the strong gravity of the black hole.

    Astronomers have used NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton X-ray observatory to discover an extremely luminous, variable X-ray source located outside the center of its parent galaxy.

    ESA/XMM Newton
    ESA/XMM Newton

    This peculiar object could be a wandering black hole that came from a small galaxy falling into a larger one.

    Astronomers think that supermassive black holes, with some 100,000 to 10 billion times the Sun’s mass, are in the centers of most galaxies. There is also evidence for the existence of so-called intermediate mass black holes, which have lower masses ranging between about 100 and 100,000 times that of the Sun.

    Both of these types of objects may be found away from the center of a galaxy following a collision and merger with another galaxy containing a massive black hole. As the stars, gas and dust from the second galaxy move through the first one, its black hole would move with it.

    A new study reports the discovery of one of these “wandering” black holes toward the edge of the lenticular galaxy SDSS J141711.07+522540.8 (or, GJ1417+52 for short), which is located about 4.5 billion light years from Earth. This object, referred to as XJ1417+52, was discovered during long observations of a special region, the so-called Extended Groth Strip, with XMM-Newton and Chandra data obtained between 2000 and 2002. Its extreme brightness makes it likely that it is a black hole with a mass estimated to be about 100,000 times that of the Sun, assuming that the radiation force on surrounding matter equals the gravitational force.

    The main panel of this graphic has a wide-field, optical light image from the Hubble Space Telescope. The black hole and its host galaxy are located within the box in the upper left. The inset on the left contains Hubble’s close-up view of GJ1417+52. Within this inset the circle shows a point-like source on the northern outskirts of the galaxy that may be associated with XJ1417+52.

    The inset on the right is Chandra’s X-ray image of XJ1417+52 in purple, covering the same region as the Hubble close-up. This is a point source, with no evidence seen for extended X-ray emission.

    The Chandra and XMM-Newton observations show the X-ray output of XJ1417+52 is so high that astronomers classify this object as a “hyper-luminous X-ray source” (HLX).

    These are objects that are 10,000 to 100,000 times more luminous in X-rays than stellar black holes, and 10 to 100 times more powerful than ultraluminous X-ray sources, or ULXs.

    At its peak XJ1417+52 is about ten times more luminous than the brightest X-ray source ever seen for a wandering black hole. It is also about 10 times more distant than the previous record holder for a wandering black hole.

    The bright X-ray emission from this type of black hole comes from material falling toward it. The X-rays from XJ1417+52 reached peak brightness in X-rays between 2000 and 2002. The source was not detected in later Chandra and XMM observations obtained in 2005, 2014 and 2015. Overall, the X-ray brightness of the source has declined by at least a factor of 14 between 2000 and 2015.

    The authors theorize that the X-ray outburst seen in 2000 and 2002 occurred when a star passed too close to the black hole and was torn apart by tidal forces. Some of the gaseous debris would have been heated and become bright in X-rays as it fell towards the black hole, causing the spike in emission.

    The location and brightness of the optical source in the Hubble image that may be associated with XJ1417+52 suggest that the black hole could have originally belonged to a small galaxy that plowed into the larger GJ1417+52 galaxy, stripping away most of the galaxy’s stars but leaving behind the black hole and its surrounding stars at the center of the small galaxy. If this idea is correct the surrounding stars are what is seen in the Hubble image.

    A paper by Dacheng Lin (University of New Hampshire) and colleagues describing this result appears in The Astrophysical Journal and is available online.

    See the full article here .

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

  • richardmitnick 7:59 am on October 4, 2016 Permalink | Reply
    Tags: , , Black Holes, Do Black Holes Die?,   

    From SPACE.com: “Do Black Holes Die?” 

    space-dot-com logo


    October 3, 2016
    Paul Sutter


    Artist’s illustration of a supermassive black hole emitting a jet of energetic particles. Credit: NASA/JPL-Caltech

    Paul Sutter is an astrophysicist at The Ohio State University and the chief scientist at COSI Science Center. Sutter is also host of Ask a Spaceman, RealSpace, and COSI Science Now.

    There are some things in the universe that you simply can’t escape. Death. Taxes. Black holes. If you time it right, you can even experience all three at once.

    Black holes are made out to be uncompromising monsters, roaming the galaxies, voraciously consuming anything in their path. And their name is rightly deserved: once you fall in, once you cross the terminator line of the event horizon, you don’t come out. Not even light can escape their clutches.

    But in movies, the scary monster has a weakness, and if black holes are the galactic monsters, then surely they have a vulnerability. Right?

    Hawking to the rescue

    In the 1970s, theoretical physicist Stephen Hawking made a remarkable discovery buried under the complex mathematical intersection of gravity and quantum mechanics: Black holes glow, ever so slightly, and, given enough time, they eventually dissolve.

    Wow! Fantastic news! The monster can be slain! But how? How does this so-called Hawking Radiation work?

    Well, general relativity is a super-complicated mathematical theory. Quantum mechanics is just as complicated. It’s a little unsatisfying to respond to “How?” with “A bunch of math,” so here’s the standard explanation: the vacuum of space is filled with virtual particles, little effervescent pairs of particles that pop into and out of existence, stealing some energy from the vacuum to exist for the briefest of moments, only to collide with each other and return to nothingness.

    Every once in a while, a pair of these particles pops into existence near an event horizon, with one partner falling in and the other free to escape. Unable to collide and evaporate, the escapee goes on its merry way as a normal non-virtual particle.

    Voila: The black hole appears to glow, and in doing so — in doing the work to separate a virtual particle pair and promote one of them into normal status — the black hole gives up some of its own mass. Subtly, slowly, over the eons, black holes dissolve. Not so black anymore, huh?

    Here’s the thing: I don’t find that answer especially satisfying, either. For one, it has absolutely nothing to do with Hawking’s original 1974 paper, and for another, it’s just a bunch of jargon words that fill up a couple of paragraphs but don’t really go a long way to explaining this behavior. It’s not necessarily wrong, just…incomplete.

    Let’s dig into it. It’ll be fun.

    The way of the field

    First things first: “Virtual particles” are neither virtual nor particles. In quantum field theory — our modern conception of the way particles and forces work — every kind of particle is associated with a field that permeates all of space-time. These fields aren’t just simple bookkeeping devices. They are active and alive. In fact, they’re more important than particles themselves. You can think of particles as simply excitations — or “vibrations” or “pinched-off bits,” depending on your mood — of the underlying field.

    Sometimes the fields start wiggling, and those wiggles travel from one place to another. That’s what we call a “particle.” When the electron field wiggles, we get an electron. When the electromagnetic field wiggles, we get a photon. You get the idea.

    Sometimes, however, those wiggles don’t really go anywhere. They fizzle out before they get to do something interesting. Space-time is full of the constantly fizzling fields.

    What does this have to do with black holes? Well, when one forms, some of the fizzling quantum fields can get trapped — some permanently, appearing unfortunately within the newfound event horizon. Fields that fizzled near the event horizon end up surviving and escaping. But due to the intense gravitational time dilation near the black hole, thy appear to come out much, much later in the future.

    In their complex interaction and partial entrapment with the newly forming black hole, the temporary fizzling fields get “promoted” to become normal everyday ripples — in other words, particles.

    So, Hawking Radiation isn’t so much about particles opposing into existence near a present-day black hole, but the result of a complex interaction at the birth of a black hole that persists until today.

    Patience, child

    One way or the other, as far as we can tell, black holes do dissolve. I emphasize the “as far as we can tell” bit because, like I said at the beginning, generality is all sorts of hard, and quantum field theory is a beast. Put the two together and there’s bound to be some mathematical misunderstanding.

    But with that caveat, we can still look at the numbers, and those numbers tell us we don’t have to worry about black holes dying anytime soon. A black hole with the mass of the sun will last a wizened 10^67 years. Considering that the current age of our universe is a paltry 13.8 times 10^9 years, that’s a good amount of time. But if you happened to turn the Eiffel Tower into a black hole, it would evaporate in only about a day. I don’t know why you would, but there you go.

    See the full article here .

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  • richardmitnick 11:20 am on September 28, 2016 Permalink | Reply
    Tags: , , , Black Holes, Is There a Size Limit for Supermassive Black Holes?   

    From AAS NOVA: “Is There a Size Limit for Supermassive Black Holes?” 


    Amercan Astronomical Society

    28 September 2016
    Susanna Kohler

    In this artist’s illustration, a supermassive black hole with billions of times the mass of our Sun accretes matter in the heart of a galaxy. A new study questions whether there is a maximum mass that these monsters can attain. [NASA/JPL-Caltech]

    Supermassive black holes (SMBHs) lurk in the centers of galaxies, and we’ve measured their masses to range from hundreds of thousands to ten billion solar masses. But is there a maximum mass that these monsters are limited to?

    Observed Maximum

    Since the era when the first SMBHs formed, enough time has passed for them to potentially grow to monstrous size, assuming a sufficient supply of fuel.

    Instead, however, we observe that SMBHs in the centers of the largest local-universe galaxies max out at a top mass of a few times 10^10 solar masses. Even more intriguingly, this limit appears to be redshift-independent: we see the same maximum mass of a few 10^10 solar masses for SMBHs fueling the brightest of quasars at redshifts up to z~7.

    Accretion rate (solid) and star formation rate (dashed) vs. radius in a star-forming accretion disk, for several different values of black-hole mass. Though accretion rates start out very high at large radius, they drop to just a few solar masses per year at small radii, because much of the gas is lost to star formation in the disk. [Inayoshi & Haiman 2016]

    So why don’t we see any giants larger than around 10 billion solar masses, regardless of where we look? Kohei Inayoshi and Zoltán Haiman (Columbia University) suggest that there is a limiting mass for SMBHs that’s set by small-scale physical processes, rather than large processes like galaxy evolution, star formation history, or background cosmology.

    Challenges for Accretion

    Growing an SMBH that’s more massive than 10^10 solar masses requires gas to be quickly funneled from the outer regions of the galaxy (hundreds of light-years out), through the large accretion disk that surrounds the black hole, and into the nuclear region (light-year scales): the gas must be brought in at rates as high as 1,000 solar masses per year.

    Modeling this process, Inayoshi and Haiman demonstrate that at such high rates, the majority of the gas instead gets stuck in the disk, causing star formation at radii of tens to hundreds of light-years and never getting close enough to fuel the SMBH. The remaining trickle of gas that does accrete onto the SMBH is not enough to allow it to grow to more than 10^11 solar masses in the age of the universe.

    Cygnus A provides a stunning example of the tremendous jets that can be launched from SMBHs at the center of galaxies. [NRAO]

    What’s more, for a large enough SMBH, this trickle of gas can become so small relative to the black hole mass that the physics of the accretion itself changes, causing the inner disk to puff up and launching strong outflows and jets. Once this transition occurs, the black-hole feeding is suppressed, preventing the SMBH from growing any larger.

    The authors show that the critical mass for this transition is 1–6 x 1010 solar masses — consistent with the maximum masses that we’ve observed for SMBHs in the wild. This consistency supports the idea that the small-scale physics around the SMBH may be setting its size limit, rather than the large-scale environment around the galaxy.


    Kohei Inayoshi and Zoltán Haiman 2016 ApJ 828 110. doi:10.3847/0004-637X/828/2/110

    See the full article here .

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  • richardmitnick 7:17 pm on September 22, 2016 Permalink | Reply
    Tags: , , , Black Holes   

    From astrobites: “Black holes and populations” 

    Astrobites bloc


    Sep 22, 2016
    Paddy Alton

    TITLE: Stellar populations across the black hole mass – velocity dispersion relation
    AUTHORS: Ignacio Martín-Navarro, Jean P. Brodie, Remco C. E. van den Bosch, Aaron J. Romanowsky, and Duncan J. Forbes
    FIRST AUTHOR INSTITUTION: University of California Observatories
    STATUS: Accepted for publication in the Astrophysical Journal Letters


    A supermassive black hole is a kind of cosmic parasite that preys on galaxies. As the host galaxy grows larger, so too does the black hole, consuming gas that would otherwise be turned into stars. Worse, it guzzles gas so quickly that the gas surging down its gravity well gets superheated; the hot gas radiates strongly, heating up surrounding gas and driving it away from the black hole. This prevents it from being turned into stars, causing the galaxy to starve. This effect actually sets a limit on how fast a black hole can grow. To cap it off, it doesn’t always finish its meal, launching jets of material clear of the galaxy which expel yet more gas (there’s an obvious simile here, which I’m not going to employ for reasons of good taste).

    Naturally, all this has a profound effect on the host galaxy and its stellar population, ultimately shutting down star formation. The bigger the galaxy, the bigger the black hole – and the more aggressive it gets. A negative feedback loop is created which causes those galaxies that grow quickest to also fail quickest, a kind of cosmic ‘boom and bust‘. This leads to a tight correlation between the mass of a galaxy’s supermassive black hole and its total mass (more precisely with its velocity dispersion, which is just a stand-in for galaxy mass).

    In today’s paper, the authors search for clues as to how the presence of a supermassive black hole affected the formation of the stars that did make it before the gas supply was cut off.

    How it works:

    We know that just as there is a connection between galaxy mass and black hole mass, so too is there a connection between galaxy mass and the chemical makeup of stars. The most massive galaxies are ‘alpha-enhanced’ – a term that, like most technical language, packs in a lot of detail. Alpha elements are common elements created by sticking together a bunch of alpha particles (Helium nuclei). Their atoms therefore have atomic masses divisible by four: Oxygen, Neon, Magnesium, Silicon, Sulphur, Argon, Calcium, and Titanium, in case you haven’t got a periodic table to hand.

    (Carbon doesn’t count. It’s more like the seed to which you attach alpha particles in order to make the legitimate alpha elements. Making Carbon is hard, but once you’ve got some making alpha elements is easy. Sorry Carbon.)

    There’s another class of elements called ‘iron peak’ elements. Heavier elements tend to be rarer but there’s an exception for elements with atomic numbers similar to iron. When a galaxy is alpha-enhanced, it means that the alpha elements are more abundant relative to the iron peak elements than they are, for example, in the Sun. When this happens it’s actually telling us something interesting about the history of that galaxy. All these elements are formed in stars and released back into the wild via supernova explosions, which come in two types. Core-collapse supernovae are what you’re probably most familiar with: in these a massive star runs out of fuel, can no longer support itself against its own gravity and so collapses … before rebounding in a huge explosion. The massive stars that end in these explosions don’t last long in cosmic terms, sometimes only a few million years. By contrast, other supernovae occur when a white dwarf star (the kind of thing our Sun will eventually turn into) grows above a critical mass, probably due to wrenching material away from another star or merging with another white dwarf. These supernovae almost exclusively make iron peak elements but can’t possibly occur until you actually have some white dwarfs. That means there is a delay of several billion years while you wait for stars like the Sun to reach the end of their lives.

    This time delay is critical. If you grow a galaxy steadily, over billions of years, these late supernova start to go off. This seeds the galaxy with iron peak elements while it’s still making stars. If you grow your galaxy quickly, they still go off, but it’s too late: star formation is finished and those heavy elements sail off into the void. In either case the core-collapse supernovae go off quickly, so you make lots of alpha elements. In summary, alpha-enhancement means you formed your stars very quickly. It’s therefore significant that the most massive galaxies have massive black holes (which we think cut star formation off early on) and are also alpha-enhanced: the two effects are directly related.

    Today’s paper:

    In order to isolate the effect of the black hole, the authors look at the outliers – galaxies whose black holes are a bit more/less massive than expected given the size of the galaxy. This is shown in Figure 1. Their sample spans a wide range of masses and other galaxy properties, the idea being that the particular effect of the black hole can be isolated in this way.

    The authors’ sample of galaxies. The usual relationship between black hole mass and galaxy mass (velocity dispersion, on the x-axis, is just an indirect measurement of this) is plotted as a thick black line. Galaxies with slightly overweight central black holes are in orange, whilst those with comparatively light black holes are in blue (galaxies represented by circles are more compact than those represented by stars, but that’s not very important here). Figure 1 from the paper.

    The authors find a clear correlation between underweight black holes and younger stellar populations, bearing out the idea that less massive central black holes are not so good at cutting off star formation. In the ‘blue’ galaxies in Fig. 1 black hole growth has lagged behind galaxy growth for some reason, which has meant those galaxies were able to form stars for longer.

    Both central black hole mass and the production of alpha elements (see text) such as Magnesium, Mg, are related to galaxy mass. Here we see there is a more fundamental, direct connection between the two: those galaxies with slightly more massive central black holes than expected are also slightly more abundant in Mg than expected (and vice versa). The axes show the excess black hole mass and excess Mg enhancement respectively. Figure 3 from the paper.

    I said earlier that both central black hole mass and enhanced production of alpha elements are linked to total galaxy mass. What the authors are able to show is that there is a more fundamental direct link between the two (see Figure 2); this confirms that these correlations are no coincidence but really do arise from the theory I sketched out. The authors have shown us the direct effects of black hole feedback on the stellar populations of their host galaxies.

    See the full article here .

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

  • richardmitnick 4:34 pm on September 13, 2016 Permalink | Reply
    Tags: , , Black Holes, , , Star arrangement that hid for a decade spotted at galaxy’s heart   

    From New Scientist: “Star arrangement that hid for a decade spotted at galaxy’s heart” 


    New Scientist

    13 September 2016
    Adam Mann

    Part of our galaxy’s centre, as seen in near-infrared wavelengths. ESO/S. Gillessen et al.

    There’s a party in the galactic centre. We may have found the first solid evidence of a dense conference of stars around the Milky Way’s heart, which may one day help us observe the supermassive black hole living there.

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

    The structure is known as a stellar cusp, and it has played hide-and-seek with astronomers for more than a decade. It was first proposed in the 1970s, when models predicted that stars orbiting a supermassive black hole would jostle around every time one was devoured. Over the course of a galaxy’s lifetime, this should leave an arrangement with many stars near the black hole and exponentially fewer as you move farther away.

    But it has been hard to prove this happens. Other galaxies are too far away for us to see their centres as anything more than fuzzy blobs. Observations in the early 2000s seemed to support a cusp in the Milky Way, but better data showed that we had been tricked by obscuring dust.

    Now, Rainer Schödel at the Institute of Astrophysics of Andalusia in Granada, Spain, and his colleagues have combined images of the galactic centre to map faint old stars, which have been around long enough to settle into a cusp. They also studied the total light emitted by all stars at varying distances from our galaxy’s central black hole, and compared the results with simulations.

    Perfect probes

    These methods point to the same conclusion: the cusp exists. Around our galaxy’s central black hole, the density of stars is 10 million times that in our local area, says Schödel, who presented the work on 7 September at the LISA Symposium in Zurich, Switzerland.

    Many of those stars will eventually explode as supernovae, leaving behind black holes with masses comparable to that of our sun. If one of these merges with the black hole in the galactic centre, it will emit telltale gravitational waves that can be picked up by future observatories, like the proposed Laser Interferometer Space Antenna (LISA).


    Those waves will help figure out the mass, rotation rate and other properties of the black hole with extreme precision.

    “These stellar mass black holes would be absolutely perfect probes of spacetime around the supermassive black hole,” Schödel says.

    If the Milky Way has a cusp, then it’s likely that other galaxies do as well. That’s good news for an observatory like LISA, which may be able to pick up waves from dozens or even hundreds of interactions between stellar mass and supermassive black holes each year.

    The work is a significant advance over previous methods and seems to support the existence of a cusp, says Tuan Do at the University of California, Los Angeles. “The galactic centre is always surprising us though, so I think it would be great to take more observations to verify that there is a cusp of faint old stars,” he says.

    The next generation of enormous observatories, like the Thirty Meter Telescope and Giant Magellan Telescope, will see an order of magnitude more stars than current observatories can.

    TMT-Thirty Meter Telescope, proposed for Mauna Kea, Hawaii, USA
    TMT-Thirty Meter Telescope, proposed for Mauna Kea, Hawaii, USA

    Giant Magellan Telescope, Las Campanas Observatory, to be built  some 115 km (71 mi) north-northeast of La Serena, Chile
    Giant Magellan Telescope, Las Campanas Observatory, to be built some 115 km (71 mi) north-northeast of La Serena, Chile

    They will almost certainly observe the cusp if it’s there, Schödel says.

    See the full article here .

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  • richardmitnick 8:47 pm on September 12, 2016 Permalink | Reply
    Tags: , , , Black Holes,   

    From New Scientist: “First glimpse of a black hole being born from a star’s remains” 


    New Scientist

    12 September 2016
    Anna Nowogrodzki

    Born phoenix-like from the ashes of a dying star? Science Photo Library/Getty

    We’ve received a birth announcement from 20 million light years away, in the form of our first ever glimpse of what seems to be the birth of a black hole.

    When massive stars run out of fuel, they die in a huge explosion, shooting out high-speed jets of matter and radiation. What’s left behind collapses into a black hole, which is so dense and has such strong gravity that not even light can escape it.

    Or so the theory goes, anyway. Now, a team led by Christopher Kochanek at Ohio State University in Columbus have glimpsed something very special in data from the Hubble Space Telescope, from when it was watching the red supergiant star N6946-BH1, which is about 20 million light years from Earth.

    Fading star

    This star, first observed in 2004, was once about 25 times the mass of our sun. Kochanek and his colleagues found that for some months in 2009, the star briefly flared a million times brighter than our sun, then steadily faded away. New Hubble images show that it has disappeared in visible wavelengths, but a fainter source in the same spot is detectable in the infrared, as a warm afterglow.

    These observations mesh with what theory predicts should happen when a star that size crumples into a black hole. First, the star spews out so many neutrinos that it loses mass. With less mass, the star lacks enough gravity to hold on to a cloud of hydrogen ions loosely bound around it. As this cloud of ions floats away, it cools off, allowing the detached electrons to reattach to the hydrogen. This causes a year-long bright flare – when it fades, only the black hole remains.

    There are two other potential explanations for the star’s disappearing act: it could have merged with another star, or be hidden by dust. But they don’t fit the data: a merger would shine more brightly than the original star for much longer than a few months, and dust wouldn’t hide it for so long.

    “It’s an exciting result and long anticipated,” says Stan Woosley at Lick Observatory in California.

    “This may be the first direct clue to how the collapse of a star can lead to the formation of a black hole,” says Avi Loeb at Harvard University.

    A dark life cycle

    The find needs further confirmation, but that may not be far off. Material falling into the black hole would emit X-rays in a particular spectrum, which could be spotted by the Chandra X-ray Observatory. Kochanek says his group will be getting new data from Chandra in the next two months or so.

    If Chandra sees nothing, that doesn’t mean it’s not a black hole. In any case, the team will continue to look with Hubble – the longer the star is not there, the more likely that it’s a black hole. “Patience proves it no matter what,” says Kochanek.

    This data will help describe the beginning of the life cycle of a black hole, and will inform simulations of how black holes form and what makes a massive star form a neutron star rather than a black hole.

    Despite calling himself a “nasty pessimist”, Kochanek thinks it’s quite likely this is indeed the formation of a black hole. “I’m not quite at ‘I’d bet my life on it’ yet,” he says, “but I’m willing to go for your life.”

    See the full article here .

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  • richardmitnick 11:07 am on September 5, 2016 Permalink | Reply
    Tags: , , Black Holes, ,   

    From Ethan Siegel: “What Is The Biggest Black Hole As Seen From Earth?” 

    From Ethan Siegel


    The supermassive black hole at the core of galaxy NGC 1277 weighs in at 17 billion solar masses. But it’s too distant to be resolved from Earth. Image credit: NASA / ESA / Andrew C. Fabian / Remco C. E. van den Bosch (MPIA).

    If you collapse a large enough mass into a small enough volume, you’ll create a black hole.

    The anatomy of a very massive star throughout its life, culminating in a Type II Supernova. Image credit: Nicole Rager Fuller for the NSF.

    Every object has a gravitational field, and without enough speed, you can’t leave it; you can’t reach escape velocity.

    For black holes, where escape velocity is bigger than the speed of light at the event horizon, nothing can escape, not even light.

    Black holes may still emit light from outside the event horizon, as accelerated matter either falls in or is funneled into jets, but nothing inside the event horizon can ever escape. Image credit: ESO/L. Calçada, of an illustration of the quasar SDSS J1106-1939.

    Black holes are formed from the collapse of incredibly massive objects: ultramassive stars imploding in supernovae at the end of their lives.

    But common, stellar mass black holes, at 1-100 times the Sun’s mass, are surpassed by rarer, supermassive ones.

    The core of galaxy NGC 4261, like the core of a great many galaxies, show signs of a supermassive black hole in both infrared and X-ray observations. Image credit: NASA / Hubble and ESA.

    Almost every galaxy has one, including our Milky Way.

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

    The largest flare ever observed from the supermassive black hole at our galaxy’s center. Image credit NASA/CXC/Stanford/I. Zhuravleva et al.

    At 4 million solar masses, our black hole is only 26,000 light years away.

    Andrea Ghez, UCLA

    Other, larger, more distant galaxies, like Messier 87, have even larger black holes, reaching into the billions of solar masses.

    Three views of the center of Messier 87 and its central, 6.6 billion solar mass black hole. Images credit: Top, optical, Hubble Space Telescope / NASA / Wikisky, via Wikimedia Commons user Friendlystar; lower left, radio, NRAO / Very Large Array (VLA); lower right, X-ray, NASA / Chandra X-ray telescope.

    Later this decade, an array of radio telescopes — the Event Horizon Telescope — comes online.

    Event Horizon Telescope Array

    Event Horizon Telescope map

    The locations of the radio dishes that will be part of the Event Horizon Telescope array. Image credit: Event Horizon Telescope sites, via University of Arizona at https://www.as.arizona.edu/event-horizon-telescope.

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

    Atacama Pathfinder EXperiment (APEX)

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

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

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

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

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    Future Array/Telescopes

    ESO/NRAO/NAOJ ALMA Array, Chile

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    With a resolution of 10 micro-arc-seconds (μas), it should see the Milky Way’s supermassive black hole’s event horizon.

    The expected view of the Milky Way’s supermassive black hole through the Event Horizon Telescope. It should be the only one directly visible. Image credit: S. Doeleman et al., via http://www.eventhorizontelescope.org/docs/Doeleman_event_horizon_CGT_CFP.pdf.

    With an angular size of 19 μas, no other black hole appears larger from Earth.

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

  • richardmitnick 6:44 am on August 23, 2016 Permalink | Reply
    Tags: , , , Black Holes   

    From AAS NOVA: ” When Charged Black Holes Merge” 


    American Astronomical Society

    22 August 2016
    Susanna Kohler

    Simulated image of the two merging black holes. New research examines what happens when one of the black holes in a merger is charged. [Cornell SXS Lensing]

    Most theoretical models assume that black holes aren’t charged. But a new study shows that mergers of charged black holes could explain a variety of astrophysical phenomena, from fast radio bursts to gamma-ray bursts.

    No Hair

    The black hole “no hair” theorem states that all black holes can be described by just three things: their mass, their spin, and their charge. Masses and spins have been observed and measured, but we’ve never measured the charge of a black hole — and it’s widely believed that real black holes don’t actually have any charge.

    That said, we’ve also never shown that black holes don’t have charge, or set any upper limits on the charge that they might have. So let’s suppose, for a moment, that it’s possible for a black hole to be charged. How might that affect what we know about the merger of two black holes? A recent theoretical study by Bing Zhang (University of Nevada, Las Vegas) examines this question.

    Intensity profile of a fast radio burst, a sudden burst of radio emission that lasts only a few milliseconds. [Swinburne Astronomy Productions]

    Driving Transients

    Zhang’s work envisions a pair of black holes in a binary system. He argues that if just one of the black holes carries charge — possibly retained by a rotating magnetosphere — then it may be possible for the system to produce an electromagnetic signal that could accompany gravitational waves, such as a fast radio burst or a gamma-ray burst!

    In Zhang’s model, the inspiral of the two black holes generates a global magnetic dipole that’s perpendicular to the plane of the binary’s orbit. The magnetic flux increases rapidly as the separation between the black holes decreases, generating an increasingly powerful magnetic wind. This wind, in turn, can give rise to a fast radio burst or a gamma-ray burst, depending on the value of the black hole’s charge.

    Zhang calculates lower limits on the charge necessary to produce each phenomenon. For a 10-solar-mass black hole, he finds that the merger can generate a fast radio burst if the black hole’s charge is more than ~1012 Coulombs (roughly one billion times the charge that travels through a AA battery from full to empty). If its charge is more than ~1016 Coulombs, it can generate a gamma-ray burst.

    Limits on Charge

    Zhang’s calculations are not just useful in the hypothetical scenario where black holes are charged. They could, in fact, be a way of testing whether black holes are charged.

    As we accumulate future gravitational-wave observations (and with two observations by LIGO already announced, it seems likely that there will be many more), we will grow a larger sample of follow-up observations in radio through gamma-ray wavelengths. Our detections — or our lack of detections — of fast radio bursts or gamma-ray bursts associated with these black-hole mergers will allow us to set some of the first real limits on the charge of black holes.


    Bing Zhang 2016 ApJ 827 L31. doi:10.3847/2041-8205/827/2/L31

    See the full article here .

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  • richardmitnick 3:53 pm on August 11, 2016 Permalink | Reply
    Tags: , Black Holes, , ,   

    From New Scientist: “Einstein’s clock: The doomed black hole to set your watch by” 


    New Scientist

    18 July 2016 [Just appeared in social media.]
    Joshua Sokol


    Ladies and gentlemen, your challenger. Meet a black hole new to the neighbourhood, weighing 140 million suns. That’s nothing to sneeze at: this plucky upstart is 35 times more massive than the black hole that holds court at the centre of our Milky Way.

    And now, make way for the current champion: a black hole with a mass of 18 billion suns.

    For front-row seats to this cosmic boxing match, you’ll want to (cautiously) approach OJ 287, the core region of a galaxy 3.5 billion light years away. Here, the smaller black hole orbits its larger rival. With every trip around, it falls closer, on track to be swallowed up in about 10,000 years. But in the meantime, it’s putting up an admirable fight.

    Even though the system is so far away, OJ 287 releases enough energy to appear about as bright in the sky as Pluto. We’ve been capturing it on photographic plates since the 1880s, but it first caught the eye of Mauri Valtonen at Finland’s Tuorla Observatory in Turku almost a century later. His team noticed that unlike other galactic centres, which brighten and dim sporadically, this one seemed to keep to a tight schedule. Every 12 years, it has an outburst.

    Well, not exactly every 12 years. Not only do the outbursts look different each time, but the gap between them seems to grow shorter by about 20 days each cycle. In the decades since we noticed the pattern, we’ve gone a long way towards figuring out why.

    S. Zola & NASA/JPL

    Ancient enemies

    OJ 287’s situation is a window into what must have happened in galaxies all over the universe. Galaxies grow by eating their own kind, and almost all of them come with a supermassive black hole at the centre.

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

    Once two galaxies merge, their black holes – now forced to live in one new mega-galaxy – will either banish their rival with a gravitational kick that flings their opponent out of the galaxy, or eventually merge into an even bigger black hole.

    In OJ 287, the smaller black hole is en route to becoming a snack for the larger one. The larger one is also growing from a surrounding disc of gas and dust, the material from which slowly swirls down the drain. Each time the smaller black hole completes an orbit, it comes crashing through this disc at supersonic speeds.

    That violent impact blows bubbles of hot gas that expand, thin out, and then unleash a flood of ultraviolet radiation – releasing as much energy as 20,000 supernova explosions in the same spot. You could stand 36 light years away and tan faster than you would from the sun on Earth.

    The cymbal clash to come

    Even with all this thrashing, the smaller black hole has no chance of escape. Energy leaches away from the binary orbit, bringing the pair closer together and making each cycle around the behemoth a little shorter than the last.

    Although the outbursts may be impressive, the black holes’ orbital dance emits tens of thousands of times more energy as undulations in space time called gravitational waves.

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

    Last year, the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US offered a preview of the endgame of OJ 287 in miniature.

    LSC LIGO Scientific Collaboration
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Twice in 2015, LIGO heard gravitational waves from the final orbits of black-hole pairs in which each black hole was a few dozen times the size of the sun, and then the reverberations of the single one left behind.

    SXS, the Simulating eXtreme Spacetimes (SXS) project
    SXS, the Simulating eXtreme Spacetimes (SXS) project

    Because its black holes are so massive, the ultimate collision at the heart of OJ 287 will be too low-frequency for LIGO to hear. But the outcome will be much the same. Where once two black holes from two separate galaxies tussled, one black hole will remain, smug and secure at the centre.

    See the full article here .

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  • richardmitnick 11:09 am on August 7, 2016 Permalink | Reply
    Tags: , , , Black Holes   

    From Astronomy Now: “Do black holes have a back door?” 

    Astronomy Now bloc

    Astronomy Now

    6 August 2016
    No writer credit found

    In the 2014 science fiction film Interstellar, a group of astronauts traverse a wormhole near a black hole called Gargantua. A recent study by researchers at the Institute of Corpuscular Physics in Valencia suggests that matter might indeed survive its foray into these space objects and come out the other side. Illustration: A realistic accretion disc gravitationally lensed by a rotating black hole. Credit: Double Negative artists/DNGR/TM & © Warner Bros. Entertainment Inc./ Creative Commons (CC BY-NC-ND 3.0) license.

    One of the biggest problems when studying black holes is that the laws of physics as we know them cease to apply in their deepest regions. Large quantities of matter and energy concentrate in an infinitely small space, the gravitational singularity, where space-time curves towards infinity and all matter is destroyed. Or is it?

    A recent study by researchers at the Institute of Corpuscular Physics (IFIC, CSIC-UV) in Valencia suggests that matter might in fact survive its foray into these space objects and come out the other side.

    Published in the journal Classical and Quantum Gravity, the Valencian physicists propose considering the singularity as if it were an imperfection in the geometric structure of space-time. And by doing so they resolve the problem of the infinite, space-deforming gravitational pull.

    “Black holes are a theoretical laboratory for trying out new ideas about gravity,” says Gonzalo Olmo, a Ramón y Cajal grant researcher at the Universitat de València (University of Valencia, UV). Alongside Diego Rubiera, from the University of Lisbon, and Antonio Sánchez, PhD student also at the UV, Olmo’s research sees him analysing black holes using theories besides general relativity (GR).

    Specifically, in this work he has applied geometric structures similar to those of a crystal or graphene layer, not typically used to describe black holes, since these geometries better match what happens inside a black hole: “Just as crystals have imperfections in their microscopic structure, the central region of a black hole can be interpreted as an anomaly in spacetime, which requires new geometric elements in order to be able to describe them more precisely. We explored all possible options, taking inspiration from facts observed in nature.”

    Using these new geometries, the researchers obtained a description of black holes whereby the centre point becomes a very small spherical surface. This surface is interpreted as the existence of a wormhole within the black hole. “Our theory naturally resolves several problems in the interpretation of electrically-charged black holes,” Olmo explains. “In the first instance we resolve the problem of the singularity, since there is a door at the centre of the black hole, the wormhole, through which space and time can continue.”

    This study is based on one of the simplest known types of black hole, rotationless and electrically-charged. The wormhole predicted by the equations is smaller than an atomic nucleus, but gets bigger the bigger the charge stored in the black hole. So, a hypothetical traveller entering a black hole of this kind would be stretched to the extreme, or “spaghettified,” and would be able to enter the wormhole. Upon exiting they would be compacted back to their normal size.

    Seen from outside, these forces of stretching and compaction would seem infinite, but the traveller himself, living it first-hand, would experience only extremely intense, and not infinite, forces. It is unlikely that the star of Interstellar would survive a journey like this, but the model proposed by IFIC researchers posits that matter would not be lost inside the singularity, but rather would be expelled out the other side through the wormhole at its centre to another region of the universe.

    Another problem that this interpretation resolves, according to Olmo, is the need to use exotic energy sources to generate wormholes. In Einstein’s theory of gravity, these “doors” only appear in the presence of matter with unusual properties (a negative energy pressure or density), something which has never been observed. “In our theory, the wormhole appears out of ordinary matter and energy, such as an electric field” (Olmo).

    The interest in wormholes for theoretical physics goes beyond generating tunnels or doors in spacetime to connect two points in the universe. They would also help explain phenomena such as quantum entanglement or the nature of elementary particles. Thanks to this new interpretation, the existence of these objects could be closer to science than fiction.

    See the full article here .

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