Dr. Julia Comerford is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the University of Texas at Austin. A wealth of observations have shown that galaxy mergers are common and that nearly all galaxies host a central supermassive black hole (SMBH); consequently, some galaxies must host two SMBHs as the result of recent mergers. The two SMBHs are known as "dual SMBHs" for the first ~100 Myr after the merger when they are at separations >1 kpc. These dual SMBHs have significant potential as probes of galaxy evolution, as they are observational tracers of galaxy mergers, the role of active galactic nuclei (AGN) in galaxy mergers, and SMBH mergers. However, the full potential of dual SMBHs for studies of these topics has not yet been realized, due to the small number of known dual-SMBH systems. Dr. Comerford proposes to use optical spectroscopy to increase the number of known dual SMBHs several folds and build a statistical catalog of 0 < z < 2 dual SMBHs. She will use her dual-SMBH catalog to constrain the galaxy merger rate, mechanisms for AGN fueling and feedback in galaxy mergers, and the number of SMBH mergers that should be detected by future gravitational-wave experiments such as the Laser Interferometer Space Antenna (LISA).
Dr. Comerford will also teach science communication workshops for astronomy undergraduates to increase the students' effectiveness in communicating to the general public and to the astronomical community. Undergraduate workshop participants will share their research experiences with minority high school students at Eastside Memorial High School in Austin. In addition, to extend the development of scientific communication skills beyond Austin, Dr. Comerford will initiate an annual one-day Undergraduate Research Symposium for astronomy majors from the University of Texas at Austin, Texas A&M University and Rice University.
The research goal of this project was to discover and characterize galaxies that host dual supermassive black holes. Nearly every galaxy hosts at its center a supermassive black hole of a million to a billion times the mass of the Sun. When two such galaxies merge, this brings their two supermassive black holes together as dual supermassive black holes. Dual supermassive black holes are valuable tracers of many phases of galaxy evolution, including the mass growth of supermassive black holes. However, the potential of dual supermassive black holes for such studies has been limited by the observational challenge of detecting them. This project developed a new observational approach to dual supermassive black hole discoveries, which included a combination of ground-based optical spectroscopy and space-based X-ray observations. The results of this project suggest that the occurrence rate of dual supermassive black holes follows the galaxy merger rate, and that galaxy mergers play a significant role in the mass growth of supermassive black holes. The educational goal of this project was to promote undergraduate research in astronomy. The highlights of this project’s education activities included a new website promoting undergraduate research opportunities in astronomy, classes that taught research presentation skills to undergraduates, and the creation of a Texas Astronomy Undergraduate Research Symposium. Over the last three years, 56 students have given talks at these symposia about their research in astronomy. The undergraduate students represented eight universities throughout Texas: UT Austin, Texas A&M, Rice University, Texas Christian University, Texas Lutheran University, Baylor University, UT Brownsville, and UT San Antonio.
