Connecting Galaxy Black Hole Mass with the State of the Circumgalactic Medium

This proposal directly addresses a missing link in the story of galaxy formation: the physical connection between feedback from a galaxy's supermassive black hole and the kiloparsec-scale gas flows that comprise the circumgalactic medium (CGM). Now well-established, the relationship between the properties of the highly-ionized CGM and a galaxy's star formation history is one of the most surprising and informative results from the last decade of HST/COS observations. Similar to the black hole (BH) M-sigma relation, such a global relationship likely reflects multi-scale feedback processes. We have assembled a novel sample of eight nearby ~L* galaxies for which the SMBHs have dynamically resolved mass measurements, and which have nine FUV-bright background QSOs close on the sky ( Rproj < 130 kpc). The sample galaxies span a narrow range in stellar mass, but host SMBHs that vary in mass by nearly two orders of magnitude. COS spectroscopy of the background QSOs will establish the relationship between the cumulative feedback energy associated with long-term BH growth (as traced by the BH mass) and the content and kinematics of the gaseous halos around these systems. Specifically, we will measure CIV column densities and kinematics to test two predictions: (1) that galaxies with more massive BHs have more evacuated CGMs; and (2) that more massive BHs drive more extreme halo gas kinematics. The HST/COS/G160M observations we propose will be the first and only empirical test to constrain the existence of any such connection between long-term SMBH growth and the physical state of the surrounding halo gas.