Tell-tale electromagnetic signatures of massive black hole binaries
Jordy Davelaar (CCA/Flatiron Institute and Columbia University)
Due to galactic mergers, massive black hole binaries are thought to reside in the cores of numerous galaxies. As the massive black holes migrate inwards, they will eventually emit gravitational waves, which are expected to be detected by LISA. A critical component to understanding where and how black holes merge and how they shape galactic evolution is host galaxy identification, which relies on electromagnetic (EM) observations. In my talk, I will show two novel tell-tale EM signatures that would provide strong evidence for a black hole binary before or during a merger. The first is when the binary is seen close to edge on; in that case, the binary produces self-lensing flares (SLFs) when one of the black holes moves in front of the background black hole. This causes the emission to be gravitationally lensed. This signal can additionally hold information on the size and shape of the emission morphology of the lensed black hole. Secondly, I will argue that when the binary is close to merger, the accretion is disrupted, turning the binary X-ray dark. I will argue that the upcoming time-domain surveys and X-ray mission might be able to observe these signatures, and that they could be crucial for LISA source identification.
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