Dirty black holes are interesting Print

One of the most awe-inspiring properties of black holes is their absolute simplicity, or as John Wheeler famously put it, “black holes have no hair”. As their progenitor collapses, its memory is forever lost, and all that remains is a quiescient, almost featureless, black hole. In a new article to appear in Physical Review Letters, our group questions whether this conclusion applies to realistic, astrophysical black holes

Isolated, “clean” black holes are almost xeroxed copies of one another, differing at most in mass and rotation. These objects are described by a solution discovered by Roy Kerr in 1963. Remarkably, Kerr black holes are ubiquitous in almost any other theory of gravity, to the extend that the “Kerr hypothesis” is the current paradigm in astrophysics.

We have shown that in simple, well-motivated extensions of Einstein’s theory known as scalar-tensor theories, black holes may not be described by the Kerr metric, as was previously thought. The crucial ingredient is the matter surrounding astrophysical black holes, typically in the form of accretion disks. The presence of matter in such “dirty” black holes forces the hairless Kerr black hole to develop a new charge — new “hair” — anchoring it to the surrounding matter and possibly to the entire galaxy”.

This hair growth is accompanied by a peculiar emission of gravitational waves, potentially detectable by upcoming laser interferometers, which may test the Kerr hypothesis and probe the very foundations of gravity.

See the media blurb on our article, in New Scientist, Huffington Post, and Público .

Last Updated on Monday, 07 October 2013 04:35