The Formation and Early Growth of Supermassive Black Holes in the Universe's First Two Billion Years

• Applicant: Dr. Jan-Torge Schindler
• Subject Area: Astrophysics and Astronomy
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 518006966

Supermassive black holes (SMBHs) reside at the centers of almost all massive galaxies. They grow by merging with other SMBHs and, more predominantly, through accretion of gas. In the standard picture of SMBH growth gravitational potential energy is converted into radiation via the accretion disk. These physics imply that active galactic nuclei (AGN) and the more luminous quasar phases are concomitant with the buildup of SMBH mass. The existence of quasars at redshifts z>7, only 800Myr after the Big Bang, with billion solar mass SMBHs challenges our understanding of SMBH growth. According to our standard model it would take more than 900Myr, longer than the age of the universe at the time, to grow them from stellar remnants. To address this puzzle tracking the populations of quasars towards higher redshifts and characterizing their demographics is essential. The imminent launch of ESA/Euclid and the capabilities of the James Webb Space Telescope (JWST) will be transformative for new high-redshift quasar discoveries. Euclid will detect more than 100 quasars at z>7 a tenfold increase over the 10 sources currently known. And JWST will deliver exquisite spectra to measure their properties. However, with current quasar selections more than 100 candidates are spectroscopically observed to discover only one z>7 quasar. This efficiency is simply unacceptable for the fainter candidates Euclid will deliver. Building on my expertise in machine-learning driven quasar discoveries, with this program I will develop more efficient strategies to build statistically relevant samples of z>7 quasars. I will characterize their demographics, and study their physics in comparison to lower redshift analogues to address the puzzle of early SMBH formation. However, the unified model of AGN predicts a significant fraction of quasars to be obscured. To chronicle the buildup of SMBHs across cosmic time, including the obscured (type-2) quasar population is essential. Previous efforts to characterize the type-2 population have been limited to low-luminosity sources at z<2. The lack of spectroscopic samples of higher redshift type-2 quasars is a major unsolved problem. Fortunately, the advent of infrared surveys (e.g., VHS, WISE, Euclid) facilitate a systematic search for elusive z>2 type-2s over large areas. Furthermore, the increased sensitivity of new spectrographs enables confirmation spectroscopy for large samples. I propose to conduct a novel spectroscopic type-2 quasar survey at z>2. Determining high-redshift type-2 quasar demographics spectroscopically will present a major advancement towards a complete census of the high redshift SMBH population. Both research lines, the study of the first type-1 quasars and the first investigation into the obscured population at z>2, will produce major advancements to for a holistic view on the formation and early growth of SMBHs in the first 2Gyr of our universe.

• DFG Programme: Independent Junior Research Groups
• International Connection: Denmark, USA
• Cooperation Partners: Professor Xiaohui Fan, Ph.D.; Professor Joseph Hennawi, Ph.D.; Professorin Marianne Vestergaard, Ph.D.