Hidden in Plain Sight: A Panchromatic View Onto Intermediate Mass Black Holes in Extreme Emission Line Galaxies

University Of Texas At Austin, Austin TX

Investigators

Abstract

Black holes are mysterious and fascinating objects where the gravity is so strong that not even light can escape them. Supermassive black holes are a million to a billion times the mass of our Sun and are ubiquitous at the centers of massive galaxies. Supermassive Black Holes play a critical role in shaping the large-scale structure of the universe and the galaxies around them, as they influence the formation of stars and the distribution of matter through their powerful gravitational pull and energy output. This research team will help explain long-standing questions of black hole formation. Intermediate-mass Black Holes (IMBHs; 100 to 100,000 times the mass of our Sun), are one of the best theories for what seeded the first supermassive BHs, and they are expected to still reside in the smallest-scale galaxies today. A new class of low-mass galaxies has been discovered that might be powered by IMBHs. These so-called "Extreme Emission Line Galaxies" (EELGs) emit inexplicably large amounts of very high-energy light that are well beyond what stars can produce. This research also provides an exciting and natural way to bring diverse astronomers together and prepare students for graduate study. The investigator will develop a BH Summer Bridge Course, provide Postdoc Mentoring opportunities tailored to BH research and establish long-lasting affinity support groups through Writing Retreats and a Beyond Astronomy Conference. This project will address the outstanding challenges that have so far obscured a clear view of IMBHs using a novel, multi-pronged pathway for studying IMBH signatures in EELGs. The investigator will (1) use spectral energy distribution (SED)+line fitting to diagnose the relative contribution of IMBHs to the high-energy ionizing continuum; (2) measure BH masses from photoionization models that incorporate broad (~1000 km/s) Balmer emission lines; and (3) inform the growth history of SMBHs. This primary objectives are (i) learning more about the conditions in which IMBHs thrive and in which they fail to exist and (ii) constraining the source of hard ionizing radiation in EELGs. 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.