The starburst-active galactic nucleus connection: The role of young stellar populations in fueling supermassive black holes

Abstract

Tracing the star formation history in circumnuclear regions (CNRs) is a key step toward understanding the starburst-active galactic nucleus (AGN) connection. However, bright nuclei outshining the entire host galaxy prevent the analysis of the stellar populations of CNRs around type-I AGNs. Obscuration of the nuclei by the central torus provides a unique opportunity to study the stellar populations of AGN host galaxies. We assemble a sample of 10,848 type-II AGNs with a redshift range of 0.03 ≤ z ≤ 0.08 from the Sloan Digital Sky Survey's Data Release 4, and measure the mean specific star formation rates (SSFRs) over the past 100 Myr in the central 1-2kpc. We find a tight correlation between the Eddington ratio (λ) of the central black hole (BH) and the mean SSFR, strongly implying that supernova explosions (SNexp) play a role in the transportation of gas to galactic centers. We outline a model for this connection by accounting for the role of SNexp in the dynamics of CNRs. In our model, the viscosity of turbulence excited by SNexp is enhanced, and thus angular momentum can be efficiently transported, driving inflows toward galactic centers. Our model explains the observed relation λ SSFR 1.5-2.0, suggesting that AGNs are triggered by SNexp in CNRs. © 2009 The American Astronomical Society. All rights reserved.