Stellar Torques and Gas Flows in Galactic Centers: Feeding and Feedback in Nearby Active Galactic Nuclei
Abstract
Measuring the fueling and feedback in active galactic nuclei is vital to understanding the co-evolution of galaxies and their massive black holes. We have 0.1" resolution ALMA CO spectroscopic maps of the velocity fields of molecular gas in and around the centers of a representative sample of 48 nearby (d<50Mpc) AGN. We model the rotation with Diskfit revealing residuals from circular motion due to gas inflows and outflows.
We propose combining ALMA velocity maps with three observables available only from HST imaging: 1) red starlight to determine the distribution of stellar mass, which determines the gravitational potential; 2) color maps of absorption lanes to show the distribution of dust; and 3) continuum-subtracted narrow-band images of H-alpha+[NII] and [OIII] to measure the distribution of ionized gas. As demonstrated on a few galaxies, this combination of HST measurements of the stellar mass with ALMA velocity fields maps the distribution of stellar torques on gas. Where they are negative, gas flows inward, with a mass rate which we calculate. We will determine if these inflows account for the AGN accretion rate derived from bolometric luminosities; and if gas depletion timescales are comparable to AGN duty cycles. Where we detect outflows, HST images will show their impact on star formation. Our 48-galaxy sample will reveal correlations between gas inflow and outflow properties with the mass and accretion rate of the MBH, the presence of broad lines (direct or hidden), and properties of the host galaxy. We will test predictions that outflow energies are 5% of AGN luminosity. We will also perform this HST+ALMA analysis on a control sample of normal galaxies.- Publication:
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HST Proposal
- Pub Date:
- May 2020
- Bibcode:
- 2020hst..prop16143M