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We describe a method to measure the M-sigma relation in the non-local universe using dust-obscured QSOs. We present results from a pilot sample of nine 2MASS red QSOs with redshifts 0.14<z<0.37. We find that there is an offset (0.8 dex, on average) b etween the position of our objects and the local relation for AGN, in the sense that the majority of red QSO hosts have lower velocity dispersions and/or more massive BHs than local galaxies. These results are in agreement with recent studies of AGN at similar and higher redshifts. This could indicate an unusually rapid growth in the host galaxies since z~0.2, if these objects were to land in the local relation at present time. However, the z>0.1 AGN (including our sample and those of previous studies) have significantly higher BH mass than those of local AGN, so a direct comparison is not straightforward. Further, using several samples of local and higher-z AGN, we find a striking trend of an increasing offset with respect to the local M-sigma relation as a function of AGN luminosity, with virtually all objects with log(L_5100/erg s^-1) > 43.6 falling above the relation. Given the relatively small number of AGN at z>0.1 for which there are direct measurements of stellar velocity dispersions, it is impossible at present to determine whether there truly is evolution in M-sigma with redshift. Larger, carefully selected samples of AGN are necessary to disentangle the dependence of M-sigma on mass, luminosity, accretion rates, and redshift.
119 - Kyle D. Hiner 2009
We model the optical to far-infrared SEDs of a sample of six type-1 and six type-2 quasars selected in the mid-infrared. The objects in our sample are matched in mid-IR luminosity and selected based on their Spitzer IRAC colors. We obtained new targe ted Spitzer IRS and MIPS observations and used archival photometry to examine the optical to far-IR SEDs. We investigate whether the observed differences between samples are consistent with orientation-based unification schemes. The type-1 objects show significant emission at 3 micron. They do not show strong PAH emission and have less far-IR emission on average when compared to the type-2 objects. The SEDs of the type-2 objects show a wide assortment of silicate features, ranging from weak emission to deep silicate absorption. Some also show strong PAH features. In comparison, silicate is only seen in emission in the type-1 objects. This is consistent with some of the type-2s being reddened by a foreground screen of cooler dust, perhaps in the host galaxy itself. We investigate the AGN contribution to the far-IR emission and find it to be significant. We also estimate the star formation rate for each of the objects by integrating the modeled far-IR flux and compare this with the SFR found from PAH emission. We find the type-2 quasars have a higher average SFR than the type-1 quasars based on both methods, though this could be due to differences in bolometric luminosities of the objects. While we find pronounced differences between the two types of objects, none of them are inconsistent with orientation-based unification schemes.
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