Role of feedback in AGN-host coevolution: A study from partially obscured active galactic nuclei

Abstract

Partially obscured AGNs within a redshift range z=0.011∼0.256 are used to re-study the role of feedback in the AGN-host coevolution issue in terms of their [OIII]λ5007 emission line profile. The spectra of these objects enable us to determine the AGN’s accretion properties directly from their broad Hα emission. This is essential for getting rid of the “circular reasoning” in our previous study of narrow emission-line galaxies, in which the [OIII] emission line was used not only as a proxy of AGN’s bolometric luminosity, but also as a diagnostic of outflow. In addition, the measurement of Dn(4000) index is improved by removing an underlying AGN’s continuum according to the corresponding broad Hα emission. With these improvements, we confirm and reinforce the correlation between L/LEdd and stellar population age. More important is that this correlation is found to be related to both [OIII] line blue asymmetry and bulk blueshift velocity, which suggests a linkage between SMBH growth and host star formation through the feedback process. The current sample of partially obscured AGNs shows that the composite galaxies have younger host stellar population, higher Eddington ratio, less significant [OIII] blue wing and smaller bulk [OIII] line shift than do the Seyfert galaxies.