X-ray Search for Supermassive Black Hole Binaries

15 December 2019

An active frontier in (astro)physics is the mergers of supermassive black holes. From the LIGO experiment we know that black holes with masses a few to 10s times the mass of our Sun merge with each other, emitting bursts of gravitational waves. Pairs of supermassive black holes (SMBHS; with a million to more than a billion times the mass of the sun) have the potential to merge as a result of mergers of massive galaxies. It is unclear how long this process takes, so it is necessary to look for black hole pairs which may eventually merge. In “Searching for Supermassive Black Hole Binaries in the X-rays” (Liu+) we used observations from the orbiting Swift Burst Alert Telescope to look for time-varying signals in the X-ray emission from growing supermassive black holes. Variability may indicate the presence of SMBH pairs. We did not find any evidence of active black hole pairs, but made some suggestions for ways in which these types of searches could benefit from longer timescale monitoring. The paper has been resubmitted to AAS Journals after a first round of peer review and a preprint is available.