Oral Presentation
Multi-wavelength properties of Type 1 and Type 2 AGN Host galaxies in the Chandra-COSMOS Legacy Survey
Presenter: Hyewon Suh (Subaru Telescope)
We investigate the multi-wavelength properties of active galactic nuclei (AGN) host galaxies of a large sample of 3701 X-ray-selected AGNs out to z~5 in the Chandra-COSMOS Legacy Survey. Thanks to the extensive multi-wavelength photometry available in the COSMOS field, we derive AGN luminosities, stellar masses, and star formation rates (SFRs) via a multi-component SED-fitting for both Type 1 and Type 2 AGN host galaxies. Both Type 1 and Type 2 AGNs follow the same intrinsic Lx - L6um relation, suggesting that the mid-infrared emission is a reasonably good measure of the AGN accretion power regardless of obscuration. We find that there is a strong increase of Type 1 AGN fraction towards higher AGN luminosity, possibly due to the fact that Type 1 AGNs tend to be hosted by more massive galaxies. The AGN luminosity and SFR generally increase towards the high stellar mass, while both the Mstellar dependence is weaker towards the high-mass end, which could be interpreted as a consequence of quenching both the star formation and AGN activity in massive galaxies. AGN host galaxies tend to have SFRs which are consistent with normal star-forming galaxies, independent of AGN luminosities, implying that AGN activity does not significantly affect the global star formation in their host galaxies. We confirm that black hole accretion rates and SFRs are correlated up to z~5, when forming stars (i.e, Herschel-detected). On the other hand, the majority (~73%) of our AGN sample are faint in far-infrared (i.e., Herschel-undetected), implying that the moderate-luminosity AGNs seem to be still (instantaneously) active after the star formation is quenched. It is not certain whether AGN activities play a role in quenching the star formation. We conclude that both AGN activity and star formation might be more fundamentally related to host stellar mass.
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