Bruno Giacomazzo, Rosalba Perna
Neutron stars (NSs) in the astrophysical Universe are often surrounded by accretion disks. Accretion of matter onto a NS may increase its mass above the maximum value allowed by its equation of state, inducing its collapse to a black hole (BH). Here we study this process for the first time, in 3D, and in full general relativity. By considering three initial NS configurations, each with and without a surrounding disk (of mass ~7% M_{NS}), we investigate the effect of the accretion disk on the dynamics of the collapse and its imprint on both the gravitational wave (GW) and electromagnetic (EM) signals that can be emitted by these sources. We show in particular that, even if the GW signal is similar for the accretion induced collapse (AIC) and the collapse of a NS in vacuum (and detectable only for Galactic sources), the EM counterpart could allow to discriminate between these two types of events. In fact, our simulations show that, while the collapse of a NS in vacuum leaves no appreciable baryonic matter outside the event horizon, an AIC is followed by a phase of rapid accretion of the surviving disk onto the newly formed BH. The post-collapse accretion rates, on the order of ~10^{-2} M_{sun} s^{-1}, make these events tantalizing candidates as engines of short Gamma-Ray Bursts.
View original:
http://arxiv.org/abs/1209.0783
No comments:
Post a Comment