Surveying the Broad-Line Region Landscape of XRISM AGNs

Supermassive black holes are some of the most extreme objects in the universe, and it appears that every massive galaxy hosts a supermassive black hole in its center. These black holes appear to shape the growth and evolution of the galaxies in which they live. The investigators will focus on supermassive black holes that are vigorously “eating”. They will map the flows of gas into and out of the centers of these galaxies to answer several key questions about how black holes eat, and how this process in turn affects the host galaxy. The large data sets that will be collected to answer these questions will provide numerous opportunities to train students at the undergraduate and graduate level at Georgia State University, a Predominantly Black Institution with one of the most diverse student bodies in the country. The PI will pilot an initiative to increase the flow of physics majors from the Perimeter College 2-year system to Georgia State University where they may complete a B.S. in physics. The PI will also continue cultivating connections that enable public outreach opportunities to foster science literacy and appreciation in the Atlanta area and beyond. Reverberation mapping is a powerful time-domain technique that tracks light echoes in the photoionized gas around an accreting supermassive black hole, mapping out the distribution and motions of the gas using time resolution rather than spatial resolution. This program seeks to leverage advances in reverberation mapping data quality and modeling capabilities, while capitalizing on the recent launch of the X-ray telescope XRISM and its order of magnitude improvement in spectral resolution, to constrain the geometry and kinematics of gas over 4 orders of magnitude in physical scale in the nuclei of a sample of accreting black holes spanning a range of masses and luminosities. Together, these complementary observational programs will provide a momentary snapshot of the gas flows involved in feeding and feedback between 10 to 10,000 gravitational radii and will enable the investigators to discern the geometry of the accretion and ejection flows across a range of physical scales, explore the potential ejection mechanisms at play, and constrain the accretion and ejection rates near the event horizons of these supermassive black holes. The PIs will also measure the mass of each black hole from the reverberation signals and the spin of each black hole from the X-ray spectroscopy. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.