Collaborative Research: Investigations of Quasar Variability with High-Cadence Spectroscopy

This project will investigate the inner workings of quasars, which are supermassive black holes at the centers of galaxies that are pulling in large amounts of material. The material forms a hot disk around the supermassive black hole as it falls and emits across the entire electromagnetic spectrum at extremely high luminosities, making these objects visible across the entire observable universe.

Using an unprecedented dataset containing observations of thousands of quasars, this project will uncover details about the inner environments of quasars, which are important for understanding the relationship between the supermassive black holes and the galaxies they live in. This understanding is important for determining how galaxies form, evolve, and resulted in the universe that we see today.

In addition, this project will provide support for a black-hole themed summer camp at the University of Arizona and a summer bridge program for physics students at the University of Connecticut; both of these programs specifically recruit and target students from groups that are underrepresented in STEM fields.

The nature of the interaction between supermassive black holes (SMBHs) and their host galaxies is one of the major unanswered questions in studies of galaxy formation and evolution. Quasars are prime targets for investigating these questions; however, the inner regions of quasars are difficult to characterize due to their small angular size. Variability in quasars can be used to learn about the environment surrounding the SMBH from a variety of different angles, thus providing critical information for studies of AGN feedback and galaxy evolution.

The proposed project will leverage high-cadence and long-duration spectroscopic monitoring from the SDSS III/IV Reverberation Mapping Project and the SDSS-V Black Hole Mapper Reverberation Mapping Project, which are obtaining hundreds of spectral epochs for thousands of quasars. This project will make full use of these data to: (1) Measure properties of quasar accretion-disk winds by studying the variability of broad absorption features in quasar spectra.

This will measure the energy contained within these outflows, which allows us to determine whether these outflows can provide significant feedback to the quasar host galaxies; (2) Measure ensemble variability characteristics of a variety of quasar emission lines over a variety of different timescales, which provides information on physical conditions of the quasar broad-line emitting regions and identifies the false-positive rate of searches for binary black holes; (3) Do a systematic search for "extreme" variability events, which will allow us to distinguish between different models of accretion disks and energetics. The results from this study will allow us to better characterize the inner environment and accretion physics governing the activity of quasars, allowing us to better understand their interactions with the galaxies in which they reside.

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.