Electromagnetic Signatures of Supermassive Black Hole Mergers
Astronomy Spring Colloquia April 27, 2010 Tuesday, 4:30pm-5:30pm, Peyton Hall auditorium:
By Zoltan Haiman
I will review several ideas that may be useful in identifying electromagnetic (EM) emission from supermassive black hole (SMBH) binaries, focusing on SMBHs expected to be detectable in gravitational waves by the future Laser Interferometric Space Antenna (LISA). In particular, any detectable EM emission is likely to be time-variable, which should aid in this identification. I will discuss four possibilities for such variable signals: (i) roughly periodic signatures due to the orbital motion prior to coalescence, (ii) a transient "precursor" caused by the gas trapped inside the binary's orbit, and a transient "afterglow" produced by (iii) post-merger gas accretion and (iv) by merger-induced shocks in the circumbinary disk. I will discuss whether these time-variable EM signatures may be detectable, and how they can help in identifying a unique counterpart, even with the relatively poor (fraction of a square degree) sky localization provided by LISA. I will also highlight the extra science that will be enabled if an EM counterpart is found, such as constraints on SMBH accretion physics, cosmology, and gravitational physics.