An X-ray view of central engines of low luminosity quasars (LLQSO) in
  the local Universe
  We have carried out a systematic X-ray spectral analysis of a sample of low
luminosity quasars (LLQSO) to investigate the nature of the central engines of
these sources. The optically-selected LLQSO sample consists of close, known
bright active galactic nuclei (AGN) which serves as an important link between
the powerful quasars at higher redshift and local Seyfert galaxies. We find
that although the bolometric luminosities of the LLQSOs are lower than those of
the higher redshift quasars by almost an order of magnitude, their distribution
of the Eddington rate $\lambda_{\rm Edd}$ is similar. We detect a strong
anti-correlation between $\alpha_{\rm OX}$ and $L_{2500 \rm \AA}$, as has also
been detected in several other quasar studies with large sample sizes,
indicating that as the UV luminosity of the source increases, the X-ray
luminosity decreases. We do not detect any significant neutral obscuration
($N_{\rm H} \ge10^{22}\, \rm cm^{-2}$) in the X-ray spectra of the LLQSOs, and
hence rule out obscuration as a possible cause for their lower luminosity. We
conclude that the central engines of the LLQSOs function similarly to those of
the higher redshift quasars, and the difference is possibly because of the fact
that the LLQSOs have lower black hole masses. We do not find any correlation
between the molecular gas in the host galaxies and accretion states of the AGN.
This indicates that the presence of molecular gas in the host galaxies of the
LLQSOs does not significantly influence the instantaneous accretion rates of
their SMBHs.
