Disks Around Merging Binary Black Holes: From GW150914 to Supermassive Black Holes

TL;DR

This study uses general relativistic magnetohydrodynamic simulations to explore disk accretion around merging black holes, linking results to gravitational wave events and potential electromagnetic signals across different mass scales.

Contribution

It systematically investigates the robustness of accretion disk behaviors during black hole mergers across various disk models and mass scales, including stellar and supermassive black holes.

Findings

Possible electromagnetic counterparts to GW150914 could be explained by the simulations.

Observable properties like jet formation and accretion rates show modest dependence on initial disk conditions.

Simulations suggest consistent signatures across different disk models and black hole mass scales.

Abstract

We perform magnetohydrodynamic simulations in full general relativity of disk accretion onto nonspinning black hole binaries with mass ratio 36:29. We survey different disk models which differ in their scale height, total size and magnetic field to quantify the robustness of previous simulations on the initial disk model. Scaling our simulations to LIGO GW150914 we find that such systems could explain possible gravitational wave and electromagnetic counterparts such as the Fermi GBM hard X-ray signal reported 0.4s after GW150915 ended. Scaling our simulations to supermassive binary black holes, we find that observable flow properties such as accretion rate periodicities, the emergence of jets throughout inspiral, merger and post-merger, disk temperatures, thermal frequencies, and the time-delay between merger and the boost in jet outflows that we reported in earlier studies display only modest dependence on the initial disk model we consider here.