Low redshift quasars in the SDSS Stripe 82. Host galaxy colors and close
  environment
  We present a photometrical and morphological multicolor study of the
properties of low redshift (z<0.3) quasar hosts based on a large and
homogeneous dataset of quasars derived from the Sloan Digital Sky Survey (DR7).
We used quasars that were imaged in the SDSS Stripe82 that is up to 2 mag
deeper than standard Sloan images. This sample is part of a larger dataset of
~400 quasars at z<0.5 for which both the host galaxies and their galaxy
environments were studied (Falomo et al. 2014,Karhunen et al. 2014). For 52
quasars we undertake a study of the color of the host galaxies and of their
close environments in u,g,r,i and z bands. We are able to resolve almost all
the quasars in the sample in the filters g,r,i and z and also in $u$ for about
50% of the targets. We found that the mean colors of the QSO host galaxy
(g-i=0.82+-0.26; r-i=0.26+-0.16 and u-g=1.32+-0.25) are very similar to the
values of a sample of inactive galaxies matched in terms of redshift and galaxy
luminosity with the quasar sample. There is a suggestion that the most massive
QSO hosts have bluer colors.Both quasar hosts and the comparison sample of
inactive galaxies have candidates of close ($<$ 50 kpc) companion galaxies for
~30% of the sources with no significant difference between active and inactive
galaxies. We do not find significant correlation between the central black hole
(BH) mass and the quasar host luminosity that appears to be extra luminous at a
given BH mass with respect to the local relation (M_BH -- M_host) for inactive
galaxies. This confirms previous suggestion that a substantial disc component,
not correlated to the BH mass, is present in the galaxies hosting low z
quasars. These results support a scenario where the activation of the nucleus
has negligible effects on the global structural and photometrical properties of
the hosting galaxies.
