发稿时间:2019-01-07浏览次数:13

USTC Astronomy Seminar Series: Fall
The Early Growth of Supermassive Black Holes as Seen by Chandra
Fabio Vito  博士后
Pontificia Universidad Catolica de Chile
2019/01/09, 4:00pm , the 19th-floor Observatory Hall
Deep X-ray surveys provide unprecedented access to the population of accreting super-massive black holes (SMBH) at high redshift. I will present our recent results (Vito et al. 2018) on the 33 AGN. In particular, we derived a large fraction (50- 80%) of heavily-obscured (logNH>23) AGN, which does not evolve significantly from z=3 to 6 but shows a positive dependence on luminosity. Although this was already suggested by previous works, thanks to the use of the deepest X-ray data available we could investigate this behavior down to logL~42. I will show our findings on the high-redshift AGN X-ray luminosity function, focusing in particular on the slope of the faint end, accessible only by the deepest X-ray surveys. This is particularly important to assess the contribution of AGN to the cosmic reionization. All of these results
 Dr. Fabio Vito obtained his PhD in Astrophysics in 2014 from the University of Bologna, working on the high-z AGN population selected in X-ray surveys. He spent a 6-month visiting period at KICC/Cambridge working with R. Maiolino, and then moved to PSU for a postdoc (2015-2018) with W.N. Brandt, working on high-z AGN selected in the Chandra deep fields. In 2018 he started working at PUC as a CAS-CONICYT Fellow with F. Bauer. will be placed in the context of SMBH seeds formation and growth. I will also discuss how future missions like Lynx, Athena and JWST will boost our knowledge of the SMBH formation and evolution in the early universe. Finally, I will present preliminary results on a sample of QSOs at z=6-6.8 with black-hole mass (2-40 x 10^8 Msun) estimated from near-IR spectroscopy observed with Chandra. Some of these are among the faintest optically-selected QSOs targeted in X-rays at z>6, lying a few times below the knee of the high-redshift QSO luminosity function.