IPMU Colloquium

Speaker: Ilya Khrykin (Kavli IPMU)
Title: Probing the duration of quasar accretion episodes with He II proximity zones. (Posdoc Colloquium)
Date (JST): Fri, Nov 20, 2020, 15:00 - 15:30
Place: Zoom
Related File: 2594.pdf
Abstract: The duration of quasar accretion episodes is a key parameter to distinguish the models of formation and growth of supermassive black holes (SMBH), as well as potential feedback effects on their host galaxies and the intergalactic medium (IGM). However, this critical timescale, often referred to as the quasar lifetime, is still uncertain by several orders of magnitude, preventing significant progress in our understanding of the evolution of quasars. We have developed a fully Bayesian statistical method to infer the lifetimes of individual quasars from the analysis of their He II proximity zones, marginalizing over the unknown ionization state of the ambient IGM. Application of this method to the existing archival He II quasars revealed an extreme diversity of individual lifetimes. Building on these results, I will present the first precise measurement of the shape of the underlying distribution of quasar lifetimes. I will discuss our findings in the context of SMBH evolution and quasar light-curves, and show how they might explain the recent discovery of very young quasars at high redshifts.
Remarks: IPMU Postdoc Colloquium Series 13
Registration necessary from here: https://ipmu.zoom.us/webinar/register/WN_SiQNqIjNSfCUiA0na9o58g