The black hole - host galaxy relation for very low-mass quasars
  Recently, the relation between the masses of the black hole ($M_{BH}$) and
the host galaxy ($M_{host}$) in quasars has been probed down to the parameter
space of $M_{BH}\sim10^8 M_\odot$ and $M_{host}\sim10^{11} M_\odot$ at z $<$
0.5. In this study, we have investigated the $M_{BH}$ - $M_{host}$ log-linear
relation for a sample of 37 quasars with low black hole masses ($10^7 M_\odot <
M_{BH} < 10^{8.3} M_\odot$) at 0.5 $<$ z $<$ 1.0. The black hole masses were
derived using virial mass estimates from SDSS optical spectra. For 25 quasars,
we detected the presence of the host galaxy from deep near-infrared H-band
imaging, whereas upper limits for the host galaxy luminosity (mass) were
estimated for the 12 unresolved quasars. We combined our previous studies with
the results from this work to create a sample of 89 quasars at z $<$ 1.0 having
a large range of black hole masses ($10^7 M_\odot < M_{BH} < 10^{10} M_\odot$)
and host galaxy masses ($10^{10} M_\odot < M_{host} < 10^{13} M_\odot$). Most
of the quasars at the low mass end lie below the extrapolation of the local
relation. This apparent break in the linearity of the entire sample is due to
increasing fraction of disc-dominated host galaxies in the low-mass quasars.
After correcting for the disc component, and considering only the bulge
component, the bilinear regression for the entire quasar sample holds over 3.5
dex in both the black hole mass and the bulge mass, and is in very good
agreement with the local relation. We advocate secular evolution of discs of
galaxies being responsible for the relatively strong disc domination.
