Astronomers Discover Pair of Black Holes In Inactive Galaxy 45
William Robinson (875390) writes "The Astronomers at XMM-Newton have detected a pair of supermassive black holes at the center of an inactive galaxy. Most massive galaxies in the Universe are thought to harbor at least one supermassive black hole at their center. And a pair of black holes is indication of strong possibility that the galaxies have merged. Finding black holes in quiescent galaxies is difficult because there are no gas clouds feeding the black holes, so the cores of these galaxies are truly dark. It can be only detected by this 'tidal disruption event'."
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http://en.wikipedia.org/wiki/H... [wikipedia.org]
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No it doesn't. Herpetology is the study of amphibians and reptiles (which make about as much sense to study together as mammals and reptiles but whatever). "Herpeto-" comes from the greek herpeto, meaning "a creeping thing."
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In the link I provided it states ""Herp" is a vernacular term for reptiles and amphibians. It is derived from the old term "herpetile", with roots back to Linnaeus' classification of animals"
If you feel this is in error, feel free to edit the wiki.
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I prefer herpaderpology, the study of idiots.
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Closely related to ropadopology, pretending to be an idiot
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I don't watch TV. But they should've really called them balls instead of holes, they'd get a lot more attention.
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Rothschild radius is the volume around a bank in which we no longer know what happens to the money or internal policies of the bank.
It's larger than the Earth nowdays.
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"Roche's limit" is what you are looking for, but I don't know that it applies to balck holes.
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This is true, but the term he was looking for was Roche's limit. I suspect, however, that it doesn't apply to black holes. More precisely, I suspect that the Roche limit is within the Schwarzchild limit. This might, possibly, depend upon the speed with which the two holes revolve around each other...but I doubt it. Still, the math to solve that is way over my head.
An additional factor, of course, would be the rotational speed of each black hole. Things get a lot more complicated than I can solve *very*
Any chance of finding gravitational waves? (Score:4, Interesting)
The discovery of pulsars rotating around each other by Hulse and Taylor was a major confirmation of general relativity because of the way they were radiating energy in gravitational waves. Is there any way to use black holes to confirm this even more? Would it be something we could help "point" a gravitational wave detector at?
(Sorry, IANAP, so I apologize if this is a stupid question.)
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doesn't gravity and light travel at the same speed?...
If they discover the graviton, the answer to that will likely be yes. But atm, it is unknown.
I don't see how it can be so though, according to my armchair physicist understanding of relativity. Gravity is the 'shape' of space-time. In other words, it's made out of the same thing as height, width, depth, and time. If that is the case, then gravity doesn't have to 'travel' anywhere; it was already there.
That would mean gravity is instant. However, it seems to be an academic thought exercise, since gravity is
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General Relativity has a *local* Poincare symmetry, which is invariance of physical properties under translations (moving backwards and forwards in space and/or time), rotations in space, and Lorentz boosts. There is one free parameter in a locally Poincare-symmetric spacetime, and that is the speed of a massless object, which is denoted "c". Light is expected to be massless (and this holds up well in the limit of our ability to measure), whether it's particles, or waves, or something like each, or so
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One of them is that moving massive compact objects excite the gravitational field (but only slightly and the amplitude falls off rapidly), and since those excitations are waves they can interfere with one another constructively, making it possible to detect at great distances with current technology (in principle anyway), given two fast-moving (relative to one another *and* to us) highly massive very compact objects.
Not sure what interference has to do with it in general or the ability to detect it over long distances. Although GW is a little different to someone used to EM waves, because it requires a change in quadrupole moment, it is still like a radiating EM field from a change in dipole moment and just a wave in the far field. As long as there is nothing that can absorb it significantly, and there are not too many sources, it could be measured as far away as you want given travel time and a detector with a low e
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Yes, light and gravity is thought to travel at the same speed, with some measurements agreeing. The issue with why observing now would be bad is that the black holes are too far apart (even correcting couple thousand light years to couple thousandths). This means that the power emitted is lower than what it will be as they get closer, going roughly as inverse fifth power, so when they are half the current distance apart they will be emitting 32 times as much power in gravitational waves.
It also means th
Re:Any chance of finding gravitational waves? (Score:4, Informative)
. Also, their separation is by a couple thousand light years,
TFA reads:
"The separation between the black holes is quite small: 0.6 milliparsecs, or about 2 thousandths of a light year. That's about the width of our Solar System."
So gravitation waves might be seen AT that distance
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...at least.
The Sun's Hill Sphere is probably thousands of times farther out -- the point at which "everything else in the universe" can win out over slowly but surely being drawn into our solar system.
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Good catch, as I had misread another source when I made that post, and thought it said 2 thousand light years. Still two thousandths light years means their orbital period is on the order of a year. That would still be a way too slow for gravitational detectors as we have now and in the near future (especially for any on Earth that might filter out things around that period).
Observing a change in the orbit might be possible on human timescales at least, but would depend on how accurately they can locate
Increasingly important topic (Score:2)
Re:Increasingly important topic (Score:5, Funny)
Unfortunately, as always happens in such things, after the merger many stars will lose their jobs as the galaxies try to cut costs. They may also decide to outsource some of the jobs of the current stars to neighboring galaxies, and some existing customers might get screwed over as they decide to get rid of product lines the larger galaxy isn't interested in.
Mostly these things benefit the big giant holes running things.
Inactive? (Score:2)
Re:Inactive? (Score:4, Informative)
It's "inactive" in the sense that it isn't Active [wikipedia.org]. The Milky Way is also inactive.
I'm guessing that if these two black holes get close enough then that galaxy could get very active very quickly.
Lost civilizations? (Score:2)
I wonder if there were any civilizations in these galaxies which merged, which were sucked into the black holes.
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Chilling thought really, late developing civilisations struggling to develop an interstellar, even intergalactic presence, pitting their collective intelligences against the growing cold and dark and the slipknot of gravity. I wonder would we ever be able to excavate black holes to find their last transmissions.
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And even if their collective intelligence won out, it may still take them 10,000 years or so to actually fly out of it.
From our perspective...
Scientists at XMM? (Score:3)
"Scientists at XMM-Newton" - who writes this rubbish? XMM is a European space X-ray observatory in elliptical orbit around the earth. Nobody is "at" XMM.
Really? (Score:2)
The dark cores have been observed in light curves http://arxiv.org/abs/1310.5310 [arxiv.org]
Perhaps there are more black holes than we thought (Score:2)