An X-ray view of central engines of low luminosity quasars (LLQSO) in the local Universe

Abstract

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 ${\lambda }_{\mathrm{Edd}}$ is similar. We detect a strong anti-correlation between ${\alpha }_{\mathrm{OX}}$ and $L_{2500\mathring{\mathrm{A}}}$, 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 ($N_{\mathrm{H}}\ge 10^{22}\mathrm{c}{\mathrm{m}}^{-2}$) 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.

Published in the MNRAS journal

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• The origin of the vanishing soft X-ray excess in the changing-look Active Galactic Nucleus Mrk 590
• An X-ray spectral study of the origin of reflection features in bare Seyfert 1 galaxy ESO 511--G030
• Investigating the origin of the Fe emission lines of the Seyfert 1 galaxy Mrk~205
• A weakening Compton hump and soft X-ray excess detected in the Seyfert-1 galaxy MCG-02-58-22
• The ${\sigma }_{\mathrm{H}\beta }$-based dimensionless accretion rate and its connection with the corona for AGN
• A Search for X-ray/UV Correlation in the Reflection-Dominated Seyfert 1 Galaxy Mrk 1044
• Photometric Selection of type 1 Quasars in the XMM-LSS Field with Machine Learning and the Disk-Corona Connection
• A Systematic Study of the Short-Term X-ray Variability of Seyfert Galaxies I. Diversity of the X-ray Rms Spectra
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