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.