Discovery of Black Hole Spindown in the BATSE Catalogue of Long GRBs(Astrophysics and Cosmology)

概要

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The BATSE catalogue is searched for evidence of spindown of black holes or proto-neutron stars (PNS) by extracting normalized light curves (nLC). The nLC are obtained by matched filtering, to suppress intermediate time scales such as due to the shock break-out of GRB jets through a remnant stellar envelope. We find consistency within a few percent of the nLC and the model template for spindown of an initially extremal black hole against high-density matter at the ISCO. The large BATSE size enables a study of the nLC as a function of durations T_<90>. The resulting χ^2_<red> is within a 2.35_σ confidence interval for durations T_<90> > 20 s, which compares favorably with the alternative of spindown against matter further out and spindown of a PNS, whose χ^2 fits are, respectively, outside the 4_σ and 12_σ confidence intervals. We attribute spindown against matter at the ISCO to cooling by gravitational-wave emission from non-axisymmetric instabilities in the inner disk or torus as the result of a Hopf bifurcation in response to energetic input from the central black hole. This identification gives an attractive outlook for chirps in quasi-periodic gravitational waves lasting tens of seconds of interest to LIGO, Virgo and the LCGT.
2012-02-25