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Astronomers Discover Pair of Black Holes In Inactive Galaxy

Unknown Lamer posted about 2 months ago | from the ate-all-the-other-stars dept.

Space 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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45 comments

Science article!?!?! (-1)

Anonymous Coward | about 2 months ago | (#46834363)

Let's make a bunch of stupid jokes and vomit up what we learned on The "Science" Channel last night. HERP!!!!!!!!

Re:Science article!?!?! (0)

Anonymous Coward | about 2 months ago | (#46834393)

Let's make a bunch of stupid jokes and vomit up what we learned on The "Science" Channel last night. HERP!!!!!!!!

Oh dear, we appear to have an outbreak of HERPES.

Use of the word 'herp' should entitle the rest of the world to punch you in the head, one at a time, until you promise to never use it again.

Re:Science article!?!?! (2)

50000BTU_barbecue (588132) | about 2 months ago | (#46834427)

Why? It means reptile.

http://en.wikipedia.org/wiki/H... [wikipedia.org]

Re:Science article!?!?! (1)

kruach aum (1934852) | about 2 months ago | (#46834583)

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."

Re:Science article!?!?! (1)

50000BTU_barbecue (588132) | about 2 months ago | (#46834609)

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.

Re:Science article!?!?! (1)

Jason Goatcher (3498937) | about 2 months ago | (#46836907)

I prefer herpaderpology, the study of idiots.

Re:Science article!?!?! (1)

garyebickford (222422) | about 3 months ago | (#46837441)

Closely related to ropadopology, pretending to be an idiot

Re:Science article!?!?! (0)

durrr (1316311) | about 2 months ago | (#46835541)

I don't watch TV. But they should've really called them balls instead of holes, they'd get a lot more attention.

How long til they collide? (0)

Anonymous Coward | about 2 months ago | (#46834429)

I don't know enough to even know what to search for. Some name limit (Rothchild, Rorshach, something). But I do wonder what happens when these things get very close to each other...

Re:How long til they collide? (1)

durrr (1316311) | about 2 months ago | (#46835587)

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.

Re:How long til they collide? (1)

HiThere (15173) | about 2 months ago | (#46836023)

"Roche's limit" is what you are looking for, but I don't know that it applies to balck holes.

Re:How long til they collide? (0)

Anonymous Coward | about 2 months ago | (#46837163)

Black balls.

Re:How long til they collide? (0)

Anonymous Coward | about 2 months ago | (#46837297)

Actually, the person who said Schwarzchild metric was the one who's right. The Schwartzchild limit is the event horizon of a black hole, the point of no return. A Roche limit is where/when a body is torn apart by another body. It's possible for a body to fall into another body's Roche limit without the two ever colliding.

Re:How long til they collide? (1)

HiThere (15173) | about 3 months ago | (#46843577)

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* quickly. But I *suspect* that the event horizon doesn't become very permeable. (Does the rate at which the black hole emits Hawking radiation depend on how fast it is rotating? On the presence of an external gravitational field? Yiii!)

Probably the Roche limit is within the Schwartzhild limit, so none of this applies. If it does, then the black hole would probably need to disintegrate via Hawking radiation. OTOH, the problems of spinning black holes, and of charged and spinning black holes, even in isolation are so complex that I don't believe that anyone has yet solved them. (It's been decades since I looked at the question, so I may be wrong.) When you add in a rotating external gravitational field.... well, I don't trust simple assertions that work in most cases. This could well be an edge case that would yield a different result.

Gay black holes? (-1)

Anonymous Coward | about 2 months ago | (#46834559)

Can they suck each other off?

Any chance of finding gravitational waves? (3, Interesting)

jfengel (409917) | about 2 months ago | (#46834585)

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.)

Re:Any chance of finding gravitational waves? (2, Informative)

Anonymous Coward | about 2 months ago | (#46834795)

Unfortunately the black holes are separated by a distance about a billion times their size, which makes energy loss by gravitational waves rather small, and would be difficult to see a change in their orbital period. Also, their separation is by a couple thousand light years, so it would take a long observation to see much change in their orbital position, and the frequency of the emitted gravitational waves would be very, very, very low. If there were a test here, it would probably be very subtle. The prime candidates would be things close together, orbiting on the time scale of seconds or less right before a collision.

Re:Any chance of finding gravitational waves? (0)

Anonymous Coward | about 2 months ago | (#46835167)

doesn't gravity and light travel at the same speed? I mean, if we're looking at them interacting, isn't the time right to detect them?

Re:Any chance of finding gravitational waves? (1)

towermac (752159) | about 2 months ago | (#46836035)

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 the deformation of space-time by mass, you will never catch it going faster than light. The waves they refer to aren't gravity propagating outwards; but variations in the gravity, and thus space-time itself.

Re:Any chance of finding gravitational waves? (0)

Anonymous Coward | about 2 months ago | (#46836273)

General relativity gives that gravity propagates at the speed of light, without any need for gravitons. This is more obvious to think of in the case of gravity waves which are easy to seen propagating out. Although if you have a case with a gravitational body with constant velocity, the field looks like it doesn't lag behind as long as the velocity is constant (but not if it is accelerated), and an analogous situation comes up with charged particles and electric fields.

Re:Any chance of finding gravitational waves? (1)

Anonymous Coward | about 3 months ago | (#46838179)

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 something very different. Gravity is also expected to be massless, whether it's particles, or waves, or something like each, or something very different.

Our universe is well-modelled by relativistic fields filling all space and time -- and gravity can be modelled that way as well. All the main fields we have discovered so far (except gravity) also quantize. Light's field quantum is the photon, for example. So people tend to expect that gravity quantizes too. Indeed, if gravity does quantize in our universe there is likely to be a -- perhaps not straightforward or easy -- formal mathematical correspondence between general relativity and quantum gravity, although that has not yet been discovered. (There are gauge/gravity formalisms that work exactly in (hypothetical) universes that are not much like ours and that has narrowed the differences between seeing gravitation as spacetime curvature and seeing gravitation as a relativistic quantum field theory by developing improved fits between the latter approach and what we see in nature). We already have a *classical* (as in not quantum as in parameters take real-numbered values and are not constrained in terms of possible values) field theory of gravitation and that's General Relativity (GR).

One of the neat things about GR is that it is founded on equivalencies, and the classical field / curved manifold equivalence is embedded right in the Einstein Field Equation simply by moving things between the right and left sides of the equations. Consequently, gravitation can be modelled as waves in a classical field (one needs to exercise some care in choosing appropriate coordinates and so forth) moving matter about in full agreement with the usual view of matter moving in response to spacetime curvature.

Additionally, there is a generalization of the conservation of energy that exists in GR, called the conservation of energy-momentum. It follows from an analysis of GR's symmetry group and Noether's Theorem which says that wherever there is a symmetry there is a conservation law. The GR symmetry allows energy to flow between the gravitational field and the other fields, and we see many examples of this in the sky. 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.

These interference patterns are excitations in a field in which excitations are massless, so they are expected to move at 'c'.

Re:Any chance of finding gravitational waves? (1)

Anonymous Coward | about 3 months ago | (#46838439)

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 enough noise floor.

Re:Any chance of finding gravitational waves? (0)

Anonymous Coward | about 3 months ago | (#46846635)

There are lots of sources.

Its FT is nonlinear (as in gravity self-gravitates).

The field content is incredibly weak.

There is an enormous noise floor for all three of the main modes that detectors presently search for because of all of the above. Filtering out local sources of noise will be an interesting challenge for gravitatonal astronomy. In particular, the equation of state of dark matter is unknown and will be relevant as it will interact with gravitational field content much like gas and dust interferes with EM field content. We can see the latter and where it and gravitational interference coincide; we can't (yet, anyway) for DM. It is entirely possible that DM is a strong absorber of gravitational waves.

Additionally there is an analogy of the cosmological redshift that applies to gravitational waves that unfortunately is not an equivalence because of the nonlinearity of the gravitational field -- local energy along the way can produce a frequency shift in a gravitational wave sourced from a distant event, and thus the equation of state of dark energy may also be relevant. Even if we assume *arguendo* that the metric expansion of space is purely inertial we would also *have* to assume that the gravitational field content is quantized and has a small radius in order to treat its cosmological redshift the same as light's. Those are big assumptions.

The Einstein Telescope will help answer some of these questions, and given the BICEP2 results it is likely to be pushed along. Under ideal observation conditions, it should be able to look at plausible sources of gravitational waves at redshifts nearing z=4, some of which will then be amenable to study with EM astronomy and some of which might plausibly be candidates for future neutrino astronomy as well.

Re:Any chance of finding gravitational waves? (0)

Anonymous Coward | about 3 months ago | (#46846699)

That still doesn't address the issue that constructive interference wasn't relevant.

Re:Any chance of finding gravitational waves? (0)

Anonymous Coward | about 3 months ago | (#46848721)

It's relevant in the same way destructive interference is relevant.

Assuming semiclassical gravity really is a valid EFT outside black hole horizons, and ignoring the assertions about proof of quantization in the BICEP2 results, and assuming that at long distance scales the gravitational sky is homogeneous and isotropic, and at more local distance scales it looks a lot like the x-ray or gamma sky, then in all but a few slices of frequency space the random sources all cancel each other out at a detector outside local Hill spheres. The same assumption is necessarily made with respect to terrrestrial sources of gravitational waves for Earth-based observatories.

So at higher redshifts (certainly z >= 1), significant constructive interference piling up at the detector forms a nice detectable peak. This is relevant for inspirals, for example, black hole kicks, or spin reversals, or anywhere else where the source is described only very approximately by a Schwarzchild or Kerr metric using linearization, for example, and less for future detectables like neutron star quakes. You're right that it may not be relevant for SN observation, and who knows about GRBs.

Re:Any chance of finding gravitational waves? (1)

Anonymous Coward | about 2 months ago | (#46836933)

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 the period of the gravitational waves will be very long, and detectors have limited frequencies which they work over. Laser interferometers on Earth like LIGO look over maybe the 1 Hz to few kHz range, while space based ones are expected to get down to about 10^-5 Hz (waves with a period of about a day). Detection by looking at variation in timing of pulsars might give the ability to detect gravitational waves with periods on the order of 1-100 years, but would require really strong waves.(my rough estimate is this binary pair might be at least ~5 orders of magnitude too weak, although I'm less sure about some of these numbers).

Re:Any chance of finding gravitational waves? (3, Informative)

rotorbudd (1242864) | about 2 months ago | (#46835583)

. 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

Re:Any chance of finding gravitational waves? (0)

Anonymous Coward | about 2 months ago | (#46836083)

If you think about it this way, the Sun is the largest gravity source in our solar system and it has influence at least out to Pluto. Surely two massive black holes each has much greater mass then our local star.

Re:Any chance of finding gravitational waves? (1)

mythosaz (572040) | about 3 months ago | (#46837607)

...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.

Re:Any chance of finding gravitational waves? (1)

Anonymous Coward | about 2 months ago | (#46836139)

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 their relative position and notice any changes. From the numbers given (0.002 ly seperation, ~1e6 M_sun masses), that would suggest the pair is radiating ~10^33 W of gravitational waves, but the total energy of the system is ~10^49 J, and it would take ~40 million years to collide taking into account the increasing power being emitted as they get closer. We would be looking for a ~0.5 parts per trillion (10s of microseconds) change in the orbital period over the time of a year. That would take a substantial improvement in observation abilities.

Increasingly important topic (1)

l2718 (514756) | about 2 months ago | (#46834587)

As we understand galaxy formation better, galaxy mergers are an increasingly important topic. It's cool to have direct evidence of this type; probably this will spur more merger simulations designed to track the black holes.

Re:Increasingly important topic (4, Funny)

gstoddart (321705) | about 2 months ago | (#46834727)

As we understand galaxy formation better, galaxy mergers are an increasingly important topic.

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? (1)

Nidi62 (1525137) | about 2 months ago | (#46834737)

So how do they know it's inactive? Are all the lights out?

Re:Inactive? (3, Informative)

DudemanX (44606) | about 2 months ago | (#46835871)

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? (1)

Grishnakh (216268) | about 2 months ago | (#46834863)

I wonder if there were any civilizations in these galaxies which merged, which were sucked into the black holes.

Re:Lost civilizations? (1)

Intrepid imaginaut (1970940) | about 2 months ago | (#46835485)

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.

Re:Lost civilizations? (1)

towermac (752159) | about 3 months ago | (#46844613)

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...

A Nice Pair (0)

Anonymous Coward | about 2 months ago | (#46835089)

That is a Nice Pair

Scientists at XMM? (2)

xiox (66483) | about 2 months ago | (#46835385)

"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? (1)

g01d4 (888748) | about 2 months ago | (#46835967)

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'."

The dark cores have been observed in light curves http://arxiv.org/abs/1310.5310 [arxiv.org]

What is an inactive galaxy? (0)

Anonymous Coward | about 3 months ago | (#46837463)

For us scientific illiterate, what is an inactive galaxy?

Perhaps there are more black holes than we thought (1)

dtjohnson (102237) | about 3 months ago | (#46838449)

If a pair of black holes are present in a quiet galaxy, perhaps there are also black holes present where there aren't any galaxies at all...'between' galaxies. Maybe black holes were the driver for all galaxy and star formation and maybe there are more black holes than there are galaxies. Maybe way way more. Maybe such black holes are the missing dark matter that we are searching for.

Re:Perhaps there are more black holes than we thou (0)

Anonymous Coward | about 3 months ago | (#46838567)

Searches for microlensing effects sets an upper bound on the number of random black holes around that is too low to account for dark matter. Additionally, they would also have trouble accounting for things like oscillations in the cosmic microwave background, although it is possible the theories about the early universe are wrong too.

Supermassive blackhole of the information-galaxy (0)

Anonymous Coward | about 3 months ago | (#46839115)

Researches found, our informational-galaxy, commonly referred to as 'the internet' actually also has a supermassive blackhole in the center.
It is called 'Google'.
While people had difficulties for quite some time to understand the nature of it and thought it was an information-source, research showed, that it is actually absorbing more information than it is giving away, at least in the medium and long term.
According to game theory, you can only lose, when you use it regularly, you will want to have a mobile handset in order to be able to work for them everywhere and produce more data for them. Once that happens, you are lost!

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