Gravitational Waves and X‐Ray Signals from Stellar Disruption by a Massive Black Hole

Gravitational waves and X-ray flares are expected from tidal disruption ofstars by a massive black hole. Using a relativistic smoothed particlehydrodynamics code, we investigate the fate of main sequence and Helium starsin plunge orbits passing near Schwarzschild or a Kerr black holes of 10^5-6Msun. We show that quadrupole gravitational waves emitted during the tidaldisruption process are described reasonable well by a point particleapproximation even in the strong encounter case. An additional hydrodynamiccalculation based on the Godunov method indicates that shocks develop forsufficiently high tidal compressions. The shock-heating results in an X-rayflare, which for solar-type stars disrupted by 10^6Msun black holes is in thekeV range, associated with the gravitational wave signal. The hardness andduration of the X-ray flare may serve as a diagnostic of the mass of thecentral black hole.Comment: 27 pages, 10 figures, accepted for publication in ApJ, additional hydrodynamic calculation on shock development for high tidal compressio