Low-Mass Black Holes and CIV in Low-Luminosity AGN

The observed tight correlations between black hole mass and host galaxy properties evince a fundamental connection between their joint evolution. The key to understanding this co-evolution rests on the ability to measure the smallest black hole masses, which closely trace the formation of black holes. But, recent observational evidence suggests the smallest black holes and/or the smallest galaxies (especially pseudobulges) diverge from the scaling relations. There is therefore a pressing need: (1) to firmly establish multiple, independent measures of black hole mass in these smallest objects, and (2) to accurately determine properties of the host galaxy. Unfortunately, low AGN luminosity means that galaxy contamination is a prohibiting issue for normal ground-based measures of BH mass. But, in the UV this is not a problem allowing the use of CIV to measure BH masses through COS spectroscopy. Moreover, with WFC3 imaging we can unambiguously determine the bulge morphology and luminosity. Therefore, only with our proposed HST campaign to study 6 low-luminosity AGN will we be able to test whether or not the smallest black holes in the smallest galaxies are truly aberrations compared to their higher-mass counterparts.