Astronomy & Astrophysics Seminar: AGN accretion disks

Abstract:
At the center of every active galactic nucleus (AGN) is a supermassive accreting black hole (BH). The physics of active BHs is governed by three key parameters: their mass, spin, and accretion rate. We therefore observe a sample of z ~ 1.5 AGN, selected to cover a wide range in BH mass and accretion rate, with X-shooter on the VLT. Using this unique dataset, we test models of AGN accretion discs and find that most of the observed spectral energy distributions (SEDs) can be explained by thin accretion disc theory. With these models, we derive constraints on the spin of the BHs. Such constraints have thus far been limited to AGN at much lower redshift, and our results are consistent with the "spin-up" model of BH evolution. 

Seminar Organizer: Prof. Rennan Barkana