Abstract
A precise electromagnetic measurement of the sky coordinates and redshift of a coalescing black hole binary holds the key for using its gravitational wave (GW) signal to constrain cosmological parameters and to test general relativity. Here we show that the merger of ~10^{6-7}M_sun black holes is generically followed over a period of years by multiple electromagnetic flares from tidally disrupted stars. The sudden recoil imparted to the merged black hole by GW emission promptly fills its loss cone and results in a tidal disruption rate of stars as high as ~0.1 per year. The prompt disruption of a star within a single galaxy over a short period provides a unique electromagnetic flag of a recent black hole coalescence event, and sequential disruptions could be used on their own to calibrate the expected rate of GW sources for pulsar timing arrays or the proposed Laser Interferometer Space Antenna (LISA).
Highlights
General relativistic simulations demonstrated that the coalescence of a black hole binary is accompanied by the anisotropic emission of gravitational radiation, causing a typical recoil of hundreds of km s−1 for the black hole remnant (Pretorius 2005; Baker et al 2006; Campanelli et al 2006)
Dissipation of gravitational wave (GW) energy in the disc might result in a weak EM transient shortly after the merger (Kocsis & Loeb 2008), re-equilibration of the inner edge of the disc could create an X-ray brightening on a timescale of 10–103 yr (Milosavljevic & Phinney 2005), and shocks produced by the GW-induced recoil might generate EM reverberations after the recoil (Lippai, Frei & Haiman 2008) which may take ∼104yr to dissipate as enhanced infrared luminosity (Schnittman & Krolik 2008)
While previous studies have focused on mechanisms to slowly feed stars into an empty loss cone, here we show that GW recoil will instantaneously shift the loss cone to a non-empty region of phase space
Summary
General relativistic simulations demonstrated that the coalescence of a black hole binary is accompanied by the anisotropic emission of gravitational radiation, causing a typical recoil of hundreds of km s−1 for the black hole remnant (Pretorius 2005; Baker et al 2006; Campanelli et al 2006). Dissipation of GW energy in the disc might result in a weak EM transient shortly after the merger (Kocsis & Loeb 2008), re-equilibration of the inner edge of the disc could create an X-ray brightening on a timescale of 10–103 yr (Milosavljevic & Phinney 2005), and shocks produced by the GW-induced recoil might generate EM reverberations after the recoil (Lippai, Frei & Haiman 2008) which may take ∼104yr to dissipate as enhanced infrared luminosity (Schnittman & Krolik 2008) It is not obvious whether these EM signals could be distinguished from the much more abundant sources of temporal variability in single SMBH quasars. While previous studies have focused on mechanisms to slowly feed stars into an empty loss cone, here we show that GW recoil will instantaneously shift the loss cone to a non-empty region of phase space
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
