Issue |
EPL
Volume 94, Number 5, June 2011
|
|
---|---|---|
Article Number | 50002 | |
Number of page(s) | 5 | |
Section | General | |
DOI | https://doi.org/10.1209/0295-5075/94/50002 | |
Published online | 20 May 2011 |
Spinning super-massive objects in galactic nuclei up to a* > 1
Institute for the Physics and Mathematics of the Universe, The University of Tokyo Kashiwa, Chiba 277-8583, Japan
Received:
18
March
2011
Accepted:
18
April
2011
Nowadays we believe that a typical galaxy contains about 107 stellar-mass black holes and a single super-massive black hole at its center. According to general relativity, these objects are characterized solely by their mass M and by their spin parameter a*. A fundamental limit for a black hole in general relativity is the Kerr bound |a*| ≤ 1, but the accretion process can spin it up to a* ≈ 0.998. If a compact object is not a black hole, the Kerr bound does not hold and in this letter I provide some evidences suggesting that the accretion process could spin the body up to a* > 1. While this fact should be negligible for stellar-mass objects, some of the super-massive objects at the center of galaxies may actually be super-spinning bodies exceeding the Kerr bound. Such a possibility can be tested by gravitational wave detectors like LISA or by sub-millimeter very long-baseline interferometry facilities.
PACS: 04.50.Kd – Modified theories of gravity / 04.70.Bw – Classical black holes / 97.60.Lf – Black holes
© EPLA, 2011
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