Dr. Eilat Glikman is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at Yale University. Dr. Glikman will study the role of dust-obscured quasars in relation to the overall quasar population. Dust-obscured quasars are a newly discovered and thoroughly unexplored stage of quasar evolution and may represent a missing link in the path from nascent active galactic nuclei seen buried in merging ultraluminous infrared galaxies (ULIRGs) to quasars that show no signs of disruption. Dr. Glikman will (1) conduct several new surveys for dust-obscured quasars increasing the depth and area beyond existing surveys to determine their fraction in the overall quasar population and study their reddening properties as functions of luminosity and redshift and (2) use integral-field spectroscopy to study their dynamics at subarcsecond resolutions.
Dr. Glikman will also utilize her extensive experience with outreach and mentorship in a multi-pronged education effort. She will develop and teach a modern cosmology course geared towards advanced undergraduate students. In addition, she will take advantage of the Yale-New Haven Teachers Institute to pair with a local middle school science teacher to conduct hands-on astronomy activities during the school year and in intensive summer workshops. Dr. Glikman will also design a self-contained project from within the scope of the her research and work directly with undergraduate science students, with a focus on providing mentorship to women scientists. This individualized approach of fostering stimulating collegial relationships between women scientists emphasizes the importance of role models and mentors to improve the confidence and success of women in the field of astronomy.
This NSF Astronomy and Astrophysics Postdoctoral Fellowship (AAPF) supported an investigation into a sample of dust-obscured quasars -- a newly discovered and thoroughly unexplored stage of quasar evolution. Most galaxies in the Universe host supermassive black holes at their centers, both of which appear to grow in tandem. The connection between galaxies and their black holes is thought to be influenced by galaxy mergers. I identified a sample of quasars -- rapidly growing black holes -- that are enshrouded by dust and gas in their host galaxies. Most quasars identified in the literature have blue colors with strong ultraviolet emission. The so-called "red quasars" that I have identified appear to be the long-sought missing link between luminous, star formation induced by galaxy mergers and luminous, blue quasars seen in passive mature galaxies. During this program, I conducted several surveys for quasars using radio, optical and infrared observations to identify and analyze these systems. Using the FIRST radio survey combined with the 2MASS near infrared survey, I discovered 120 dust-reddened quasars by color-selecting red sources and confirming them via an extensive spectroscopic campaign, which included the collection of over 300 spectra in the optical and/or near-infrared. From the broad wavelength sampling of their spectral energy distributions I determined their dust content, and from their redshifts I determined their distances, which I used to investigate the relationships between luminosity, reddening and evolution with redshift. At every redshift, these dust-reddened quasars are intrinsically the most luminous quasars. Hubble Space Telescope images show that red quasars live in merger-dominated host galaxies, and their infrared spectra show that the black holes are under-massive relative to their host galaxies, but are feeding at their maximal rate. The body of evidence implies that luminous quasars are triggered by a major merger of two (or more) galaxies and that red quasars represent a transitional phase from completely buried black hole growth to unobscured, blue quasars. I find that red quasars make up ~20% of the overall quasar population. Based on this fraction I interpret the duration of this phase to be ∼20% as long as the duty cycle of the unobscured, blue quasar phase, which is consistent with models of black hole growth triggered by merging galaxies. I have since expanded the survey to fainter infrared luminosities using the UKIDSS survey and completed a pilot project that finds a steep increase in the number of red quasars (and their fraction in the overall quasar population) toward fainter sources. I also used the expanded sample to improve the color selection of red quasars by including longer-wavelength infrared data from the WISE survey. Using this insight, I am now undertaking two large surveys to explore the infrared-faint and radio-faint populations which will unveil in more detail the role of mergers in growing black holes over the history of the Universe. I am also now engaged in a wide-area X-ray survey to use this complementary wavelength to select quasars, including red quasars. With this multi-wavelength approach we are beginning to have a more complete picture of black hole growth and its relation to galaxy growth over the history of the Universe. The Broader Impacts component of this involved participation in "Girls Science Investigations", a program for middle school girls, originally funded through an NSF CAREER grant, that offers hands-on science exploration in a fun, confidence-building atmosphere aimed at closing the gender gap in STEM fields. In addition, I developed and taught an undergraduate astronomy course at Yale for non-majors. The course was highly successful and several students joined the astronomy program as a consequence.
