General Relativistic Simulations of Magnetized Plasmas around Merging Supermassive Black Holes
Abstract
Coalescing supermassive black hole binaries are produced by the mergers of galaxies and are the most powerful sources of gravitational waves accessible to spacebased gravitational observatories. Some such mergers may occur in the presence of matter and magnetic fields and hence generate an electromagnetic counterpart. In this Letter, we present the first general relativistic simulations of magnetized plasma around merging supermassive black holes using the general relativistic magnetohydrodynamic code Whisky. By considering different magnetic field strengths, going from nonmagnetically dominated to magnetically dominated regimes, we explore how magnetic fields affect the dynamics of the plasma and the possible emission of electromagnetic signals. In particular, we observe a total amplification of the magnetic field of ~2 orders of magnitude, which is driven by the accretion onto the binary and that leads to much stronger electromagnetic signals, more than a factor of 10^{4} larger than comparable calculations done in the forcefree regime where such amplifications are not possible.
 Publication:

The Astrophysical Journal
 Pub Date:
 June 2012
 DOI:
 10.1088/20418205/752/1/L15
 arXiv:
 arXiv:1203.6108
 Bibcode:
 2012ApJ...752L..15G
 Keywords:

 accretion;
 accretion disks;
 black hole physics;
 gravitational waves;
 magnetohydrodynamics: MHD;
 methods: numerical;
 Astrophysics  High Energy Astrophysical Phenomena;
 General Relativity and Quantum Cosmology
 EPrint:
 7 pages, 5 figures. Minor changes to match version accepted for publication on The Astrophysical Journal Letters