Poster Presentation
Are Type 2 Quasars in Merging Special in Local Universe
Presenter: Dongyao Zhao (KIAA, PKU)
Quasar is believed to be an important phase of galaxy evolution. In this work, we discuss whether the host galaxies of type 2 quasars in merging are special compared with inactive galaxies by analysing ~380 type 2 quasars and their inactive counterparts in local universe. The ~380 type 2 sample are selected from parent catalogue of Reyes et al. (2008) whose redshifts are less than 0.25 to ensure the SDSS DR7 five-band coadded images can illustrate reliable merger morphologies. The inactive galaxies are selected with same redshift and stellar mass ranges. We find that the merger fraction of local type 2 quasars is only 27%, similar with the merger fraction of inactive galaxies. Moreover, on the one hand, type 2 quasars distribute in the green valley in the CMD, and those in merging are indistinguishable with those in regular morphologies. On the other hand, inactive counterpart galaxies whose morphologies are regular concentrate in red sequence while those in merging are bluer having similar color with type 2 quasar in merging. Our results show that the merger fraction are not enhanced in type 2 quasars, and it seems that type 2 quasars in mergers are not special compared with inactive merging galaxies. Additionally, since type 2 quasar in merger and regular morphologies have similar color, AGN activity and mergers seem both contribute to the young stellar population from SF.