BHI Colloquium, February 13 | "Constraining LIGO Detectable Black Hole Mergers in AGN Disks," Saavik K. Ford | "X-ray Reverberation Mapping Accretion in AGN," Erin Kara


Tuesday, February 13, 2018, 1:30pm to 2:30pm


BHI Conference Room (211) 20 Garden Street, Cambridge

Saavik K. Ford
The City University of New York

I will present a model for stellar mass black hole binary (BHB) mergers accelerated by an active galactic nucleus (AGN) accretion disk. This model predicted the existence of 'overweight' stellar mass BHB mergers, detectable by LIGO (McKernan, Ford, et al. 2014). In more recent work, we find the rate of BHB merger by this channel can span the range 1e-4-1e4 Gpc^-3 yr^-1, depending on a
variety of poorly constrained astrophysical parameters. Thus, with LIGO's measured rates (12-213 Gpc^-3 yr^-1), we can already constrain some aspects of AGN physics. I will also present the predicted mass and spin spectrum of BH produced via this channel.
Notably, retrograde spin BH, evolving in a gas disk play a key role in the shape of the spin distribution among AGN-produced BHB mergers. Finally, I will discuss how this channel can be constrained by LIGO observations and other future theoretical and observational work.

Erin Kara
University of Maryland

Accreting supermassive black holes can produce more electromagnetic and kinetic luminosities than the combined stellar luminosity of an entire galaxy. Most of the power output from an Active Galactic Nucleus is released close to the black hole, and therefore studying the inner accretion flow--at the intersection of inflow and outflow--is essential for understanding how black holes grow and how they affect their surrounding environments. In this talk, I will present a new way of probing these environments, through X-ray reverberation mapping, which allows us to map the gas falling on to black holes and measure the effects of strongly curved spacetime close to the event horizon.

See also: Astronomy