The First Quasars and their Environments: from the Birth of Supermassive Black Holes to Cosmic Reionisation

• Applicant: Dr. Sarah Bosman
• Subject Area: Astrophysics and Astronomy
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 506672582

The birth of galaxies and black holes is finally coming within reach via observations of the first billion years after the Big Bang: the final frontier of galaxy evolution.the proposed group will capitalise on the fact that early quasars are unrivalled tools for the exploration of the high-redshift Universe, as they probe structures spanning the lightyear-scales of the first massive black holes to the cosmological scales in the inter-galactic medium. In the next 5 years, the study of high-redshift quasars is poised for exponential growth: the Euclid mission will greatly increase their numbers and JWST will enable observations at never-seen-before wavelengths. Many new discoveries will lie in this fast-paced landscape. On the largest scales, hydrogen reionisation is proving unexpectedly complex. Models of reionisation struggle to accommodate the late end of the process required by observations. Recent breakthrough analysis advances, introduced by the PI, have made measurements of reionisation with quasars truly quantitative for the first time. Further applications within the proposed group will lead to a revolution in the quantity of precision information which theories must match.Closer in, inside the megaparsec-scale ionised bubbles carved by quasars, "proximate galaxies" are offering new and powerful insights into open questions of galaxy formation and the emission properties of quasars. The PI pioneered the study of proximate galaxies by discovering the first 3 objects, a number which will increase 10-fold in this project with ongoing observational programs.Completing this picture, the quasars themselves hold clues to the onset of quasar feedback in galaxy formation, and to the mysterious origin of the first supermassive black holes. Recent observations have ruled out previously-assumed classical mechanisms for their seeding and growth. Using upcoming pan-chromatic observations of quasars, the proposed group will determine whether the processes that grow supermassive black holes are unique to early times.Our group will spearhead cutting-edge observations of the first quasars to directly advance knowledge of these far-reaching topics and inform current and future models with much-needed observational insight. The PI has a strong track record of leading accepted observational programs at many state-of-the-art facilities, making them ideally positioned to lead these next-generation studies of the early Universe. Together with the PI's membership in Euclid, LSST, and 7 accepted JWST proposals, this incoming data means that significant advancement of the field is imminent with the proposed group.

• DFG Programme: Independent Junior Research Groups
• International Connection: Italy, USA
• Cooperation Partners: Professor Joseph Hennawi, Ph.D.; Dr. Valentina D' Odorico