YCAA Seminar: Nico Cappelluti, Yale University, “Finding the progenitors of Supermassive Black Holes in the first Gyr of cosmic history”

Event time: 
Tuesday, January 24, 2017 - 2:30pm
Hours of operation: 

coffee/tea and cookies will be served in the lounge of Steinbach Hall (52 Hillhouse) starting at 2 PM.

Watson (), A-51 See map
60 Sachem St
New Haven, CT 06511
Event description: 

Supermassive Black Holes are the most enigmatic objects in the Universe, their growth and evolution have been witnessed by X-ray and multi-wavelength cosmological surveys from the present day back to when the Universe was about 1 Gyr old (redshift z~7). Impressively, by that time the Universe has been capable of growing Black Holes to a billion solar masses, as discovered by the Sloan Digital Sky Survey. There is no known accretion process capable of growing an ordinary stellar black hole to such a high mass in such a short time. This is the so-called “Billions Problem.” However, the lack of metals in the early Universe means that the first generation of black holes was probably unusually massive (100-10^5 M_☉), arising either from evolved first-generation stars or from Direct Collapse to a Black Hole. Both types should be visible in the X-ray band. To date there have been no direct X-ray detections of this first generation of black holes. However, studies of cosmic background fluctuations provide clues to their demography and environment. In particular, we discovered, using NASA’s Chandra and Spitzer Great Observatories, that the Cosmic Background Light angular fluctuations are coherent at several wavelengths from FAR-IR to X-ray (after removing all the detected sources). These, strong, joint fluctuations can be explained with a population of very high-redshift (z>>7), low metallicity, Compton-thick, massive black holes, likely produced by the collapse of pristine clouds of molecular hydrogen. Cosmic backgrounds are therefore extremely information rich tools. They also carry important information on the nature of Dark Matter or the existence of a sterile neutrino with mass of a few keV. Over the next few years, new facilities like JWST, Euclid, WFIRST, eROSITA, and Athena—and STAR-X, Lynx, and equivalent X-ray missions—will allow to both directly detect the first black holes in the Universe and to make 1% measurements of the Cosmic Background fluctuations in as many as 20 wavelength bands.

Open to: 
Yale Community Only