| Name: Sindhu Satyavolu Affiliation: Tata Institute of Fundamental Research Conference ID: ASI2023_240 Title : Evidence for obscured growth of supermassive black holes in the first billion years Authors and Co-Authors : Sindhu Satyavolu, Girish Kulkarni, Laura C. Keating, Martin G. Haehnelt Abstract Type : Oral Abstract Category : Extragalactic Astronomy Abstract : How billion-solar-mass black holes came to be when the universe was as young as a billion years old is an open problem. The so-called proximity zones of quasars at redshifts z > 6 provide a means of constraining black hole growth via their effect on the surrounding inter-galactic medium (IGM). Recent measurements of high-redshift quasar proximity zones have yielded surprisingly small proximity zones and therefore short quasar lifetimes, thereby deepening the mystery of black hole formation. In this talk, I will use new high-dynamic-range simulations of the IGM to critically examine the assumptions made in these traditional inferences of quasar lifetimes from proximity zone sizes. I will show that the patchiness of reionization can relieve the tension between the proximity zone sizes and black hole masses to some degree, but not fully. I will then demonstrate that what is needed to explain the small proximity zone sizes is quasar variability with short duty cycle and brief bright periods. This conclusion, when combined the measurements of black hole masses of these quasars, directly leads to a prediction of significant obscuration in high-redshift quasars. I will end my talk by arguing that this prediction can be directly tested using JWST. |