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Apr 30, 2009 12:05 PM | 13
Black holes are thought to be common in the universe, with a supermassive gobbler lurking at the core of galaxies such as our own Milky Way. But might they also be found roaming outside the galactic centers?
A new study estimates that approximately 300 black holes may lurk throughout the Milky Way, remnants of the building blocks that came together billions of years ago to form the galaxy. What is more, those black holes may retain properties that would allow astronomers to identify them, providing an archaeological record of the galaxy's formation.
Ryan O'Leary, a graduate student at the Harvard-Smithsonian Center for Astrophysics (CfA), and CfA professor Avi Loeb conducted the research, set to be published in the Monthly Notices of the Royal Astronomical Society.
As galaxies merge, so do their respective central black holes. Previous studies have theorized that the final stage of black hole mergers in low-mass galaxies could release enough energy in the form of gravitational waves, or ripples in the fabric of space and time, to knock the resulting black hole right out of its parent galaxy. This recoil would not be powerful enough, however, to eject the black hole from the Milky Way's gravitational clutches, leaving these free-floating gobblers embedded within the Milky Way.
O'Leary and Loeb simulated the mergers of smaller galaxies in the Milky Way's history, finding that recoiled black holes, ranging in size from roughly 1,000 to a few hundred thousand times the mass of the sun, could exist in relatively large quantities in the Milky Way. (That is small relative to the supermassive black hole presumed to lurk at the Milky Way's core, which has a mass of some four million suns.) None would be particularly close by, the researchers say—at least a few thousand light-years away.
Critically, the study's authors write, each of these ejected black holes should be accompanied by a tight cluster of stars that it ripped from the core of its parent galaxy, and those stars could aid in identifying the rogue black holes. At such large distances, each of those clusters will likely appear as a single point of light, but O'Leary and Loeb suggest some distinguishing features that might aid in their identification, such as their high mass-to-light ratio, given the massive but nonluminous black hole at their center.
Image credit: David A. Aguilar (CfA)
Tags:
black hole merger,
rogue,
harvard,
astrophysics,
recoil
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13 Comments
Add Comment"supermassive gobbler" ?
Reply | Report Abuse | Link to thisIs that type of dumbed-down language really necessary?
My new physics theory says that every gravity is causally centered by a black hole, including the gravity field we call an atom. The maximally spinning hole literally stirs the dark matter ideal fluid ether--- to cause the inward pushing on orbiting visible mater.
Reply | Report Abuse | Link to thissecond answer due to typing error. My new physics theory says there are countless maximally spinning black holes--because every nested gravity field must be centered by one --so that the ideal fluid dark matter ether is literally stirred in real time to strucrure the each field into concentric shells capable of orbiting visible matter. In the case of the atom as gravity field, the electron is the quantum visible masa whixh populates the shells in a 3-D way.
Reply | Report Abuse | Link to thisone more ttime to object to the faintness of the typng as I type, it is difficult to see well enougn to to type with good clarity---could you do something for old very smart people who cannot see as well but read whole sentences instead of word by word---l typos seldom stop us from getting meaning---faint yellow is definitely "kid"stuff' to me!!!
Reply | Report Abuse | Link to thisWhat ridiculous idea that only 300 stars in the history of are galaxy were ever big enough to become black holes.I think someone needs to recheck the math on this one.Maybe a decimal point or two off?
Reply | Report Abuse | Link to thisCan black holes really move ?
Reply | Report Abuse | Link to thisMy question stems from my belief that the Bekenstein-Hawking Entropy (which states that the amount of information that a black hole can contain is proportional to the area of the event horizon) does not allow such a phenomenon. I'll explain...
1) The Compton wavelength represents a limit to the uncertainty to which a particles location may be measured.
2) The Compton wavelength of a miniature black hole is approximately the Planck Length.
3) For a black hole of fixed energy and size, we can define a specific entropy (information), which is equivalent to counting the number of Planck Areas.
4) If an observer could move towards or away from a black hole, one would expect there to be space dilation/contraction (or equivalently red/blueshifting of the compton wavelength). Although one cannot see the Black hole, the perceived change in matter density would affect gravitational lensing.
5) If such contraction could occur, the information that a black hole contains would change according to the reference frame of the observer, as the surface area of the black hole would no longer be fixed.
6) There has to be something wrong about step 4.
7) One can avoid this problem by assuming a black hole to be a flat 2D object whose dimensions are always perpendicular to that of the observer and hence not subject to length contraction. However, this solution prohibits movement in directions parallel to the black holes span, which make the conceptualization of an orbiting black hole quite difficult.
8) What's the solution?
42
Reply | Report Abuse | Link to thisI'm actually a little shocked about the subject of this article. According to some reading I've done (A Brief History of Time and The Three Big Bangs), black holes are supposedly a common event. All you need is a star of a certain mass (which is hardly a remarkable value) undergoing a type-II supernova and BAM, black hole. These don't always become black holes - again, it's based on mass.
Reply | Report Abuse | Link to thisThis is based on ideas by Schwartzchild, Shandrasekhar, and others who have postulated that certain mass densities can be sufficient to overcome Pauli exclusion, resulting in ultradense matter. The lightest form is represented by white dwarfs, which are collapsed stars that have overcome the first stage of this exclusion to form very dense bodies.
The second form is that of neutron stars, which have overcome valence cloud repulsion and formed literal seas of atomic nuclei. And of course the final form is that of black holes, which are so massive that they collapse all matter into a singular point (hence the term singularity).
All that aside, the point I was making is that there are plenty of stars in our galaxy which fulfill these requirements, and considering how long the universe has been around there's no reason to suspect many haven't already made this transformation. So what's with people being surprised at the idea that we have black holes floating around? It's not weird at all.
What kind of study is this? It shows no actual research, so it seems like a really bad anectdotal study
Reply | Report Abuse | Link to thisOooh. Little theory says what a black hole behaves like from the inside. Little theory explains how matter goes inside when time dilation says time slows and stops on the horizon. Little theory says how the singularity can become so dense in less than 8 dimensions. Little is said about the swartz radius inside every object with mass, and how quantum entry into such is avoided.
Reply | Report Abuse | Link to thisAll talk of coriollis acceleration is avoided when calculating the singularity energy, and does this evaporate mass, or reduce density?
Is it true the gravitational field of a spinning black hole is extended in a plane perp to the axis of spin?
Apart from http://sites.google.com/site/jackokring is there anyone else working on commutative quantum mechanics?
Pyramids, how built
Reply | Report Abuse | Link to thisIs it possible a huge asteroid or comet crashed into the moon slowing it down just making it tumble and then being caught between the gravities of earth and the moon allowing the building of the pyramids around the world due to reduced gravities as the asteroid or comet and moon pasted overhead?
If it were a comet made of ice, the disappearance into or atmosphere would be logical as it would evaporate as pieces were pulled in by the Earth’s gravity.
I'm going to go off-topic at first, then veer back to it to close. I can't find a thread on this site talking about Dark Matter. If it exists, DM might well have something to do with all black holes (BH's.) My simpler speculation, however, concerns the well-known elliptical orbits that planets trace out in our solar system, which have Old Sol at one foci of the ellipse and ??? at the other foci. I've always wanted to plug something in to that ??? and the center of mass of DM for the planet-sun pair in consideration would suggest itself. Of course, this would make DM rather lumpy, but some study suggests that DM hangs out with ordinary matter pretty closely but not necessarily precisely.
Reply | Report Abuse | Link to thisNow, why wouldn't a BH have at least a DM halo? Out there with the accretion disk or someplace, maybe closer. If we can locate a BH somewhere reasonably nearby we could use it for slingshotting a spacecraft. We use Jupiter for this but we should be able to shoot right by close the event horizon and snap a few pics, but as long as we have built a flexible spacecraft that allows for tidal distortion it will shoot on by the BH and actually be flung away quite efficiently if the BH has a good velocity in space itself. In fact, this is an interesting way of extracting energy from the BH and slowing it down.
CAN SOMEONE PLESAE EXPLAIN ME ABOUT WHY ARE THERE 2 PHOTON SPHERES FOR A ROTATING BLACK HOLE?
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