Did GW150914 produce a rotating gravastar?
Abstract
The interferometric LIGO detectors have recently measured the first direct gravitationalwave signal from what has been interpreted as the inspiral, merger and ringdown of a binary system of black holes. The signaltonoise ratio of the measured signal is large enough to leave little doubt that it does refer to the inspiral of two massive and ultracompact objects, whose merger yields a rotating black hole. Yet, the quality of the data is such that some room is left for alternative interpretations that do not involve black holes, but other objects that, within classical general relativity, can be equally massive and compact, namely, gravastars. We here consider the hypothesis that the merging objects were indeed gravastars and explore whether the merged object could therefore be not a black hole but a rotating gravastar. After comparing the real and imaginary parts of the ringdown signal of GW150914 with the corresponding quantities for a variety of gravastars, and notwithstanding the very limited knowledge of the perturbative response of rotating gravastars, we conclude it is not possible to model the measured ringdown of GW150914 as due to a rotating gravastar.
 Publication:

Physical Review D
 Pub Date:
 October 2016
 DOI:
 10.1103/PhysRevD.94.084016
 arXiv:
 arXiv:1602.08759
 Bibcode:
 2016PhRvD..94h4016C
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 6 pages, 4 figures. Extended and improved discussion of the ringdown. Conclusions unchanged and strengthened