Black Hole in Search of a Home

jose parinas writes "Interesting news from the ESO observatory on Paranal about black holes that travel. From the article: 'For 19 of [the low redshift quasars], they found, as expected, that these super massive black holes are surrounded by a host galaxy. But when they studied the bright quasar HE0450-2958, located some 5 billion light-years away, they couldn't find evidence for an encircling galaxy. This, the astronomers suggest, may indicate a rare case of collision between a seemingly normal spiral galaxy and a much more exotic object harbouring a very massive black hole.'" More from the article: "Has the host galaxy been completely disrupted as a result of the collision? It is hard to imagine how that could happen. Has an isolated black hole captured gas while crossing the disc of a spiral galaxy? This would require very special conditions and would probably not have caused such a tremendous perturbation as is observed in the neighbouring galaxy. Another intriguing hypothesis is that the galaxy harbouring the black hole was almost exclusively made of dark matter." Update: 09/17 00:15 GMT by Z : Edited for clarity.

Comments

Re:Stephens theories,....

[Tango42]

You mean Hawking radiation? From what I remember, Hawking radiation is inversely proportional to the size of the black hole, so the radiation emited from a supermassive black hole like those in Quasars is almost non-existant.

Re:adoption

[Xilman]

In fact, tidal forces at decent proximity to the event horizon will make protons and neutrons flow like water (the quarks and gluons in some cases as well...)

Only for sufficiently small black holes. There is nothing locally special about a region near the event horizon. If the BH is big enough, 100M solar masses say, the tidal forces at its event horizon are small enough to let an astronaut pass through it without ill-effect. The same can not be said of the experiences encountered much closer to the singularity.

Paul

Re:Why couldn't it have

[Alsee]

What do you mean by 'the stars in the galaxy have no "incentive"'? Is the gravity of the black hole not enough to get the stars moving towards it?

Is the gravity of the sun not enough to get the earth moving towards it? Is the gravity of the earth not enough to get the moon moving towards it?

Same thing. If there is non-zero angular momentum then gravity does not cause things to fall in, it causes them to orbit. Orbits can only decay and "fall in" if you find some way to bleed of the angular momentum. For example low earth orbit satellites slowly bleed off a little bit of angular momentum and eventually fall down due to the extremely thin atmospheric drag.

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