The low-mass end of the M BH/M host relation in quasars

Abstract

The M BH-M host relation in quasars has been probed only in a limited parameter space, namely, at M BH ∼ 10 9 M and M host 10 12 M . Here we present a study of 26 quasars laying in the low-mass end of the relation, down to M BH 10 7 M⊙. We selected quasars from the SDSS and HST-FOS archives, requiring modest M BH (as derived through the virial paradigm). We imaged our sources in H band from the Nordic Optical Telescope. The quasar host galaxies have been resolved in 25 out of 26 observed targets. Host galaxy luminosities and stellar masses are computed, under reasonable assumptions on their star formation histories. Combining these results with those from our previous studies, we manage to extend the sampled parameter space of the M BH - M host relation in quasars. The relation holds over 2 dex in both the parameters. For the first time, we are able to measure the slope of the M BH - M host relation in quasars. We find that it is consistent with the linear case (similarly to what observed in quiescent galaxies). We do not find any evidence of a population of massive black holes lying below the relation. © 2012 Roberto Decarli et al.