Changing-Look AGNs — I. Tracking the transition on the main sequence of quasars. (arXiv:2206.10056v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Panda_S/0/1/0/all/0/1">Swayamtrupta Panda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sniegowska_M/0/1/0/all/0/1">Marzena Śniegowska</a>
This paper is the first in a series of preparing and analyzing spectral and
other properties for a database of already discovered Changing-Look Active
Galactic Nuclei (CL AGNs). Here, we focus on the spectral fitting and analysis
of broad emission lines in an exhaustive sample of 112 CL AGNs available in the
literature with existing SDSS/BOSS/eBOSS spectroscopy. Additionally, we have
gathered older/newer spectral epochs from all the available SDSS data releases
to make the database more complete. We use PyQSOFit and perform a homogeneous
spectral decomposition of all of our SDSS spectra and tabulate the AGN
continuum and emission-line properties per epoch per source, chronologically.
This further allows us to categorize the sources in our sample as Turn-On or
Turn-Off and subsequently check for repeated occurrences of such phases. We
then estimate the black hole mass (M$_{rm BH}$) and the Eddington ratio
($lambda_{rm Edd}$) per epoch per source where the required parameters are
available and well-estimated. We realize the movement of the source in the
M$_{rm BH}$-$lambda_{rm Edd}$ plane allowing us to check for systematic
changes in the source’s fundamental properties. We then track their transition
along the optical plane of the Eigenvector 1 (EV1) schema and categorize
sources that either stay within the same Population (A or B) or make an
inter-population movement as a function of spectral epoch. We also test the
Balmer decrement (H$alpha$/H$beta$) of a subset of our sample of CL AGNs as a
function of time and AGN luminosity.
This paper is the first in a series of preparing and analyzing spectral and
other properties for a database of already discovered Changing-Look Active
Galactic Nuclei (CL AGNs). Here, we focus on the spectral fitting and analysis
of broad emission lines in an exhaustive sample of 112 CL AGNs available in the
literature with existing SDSS/BOSS/eBOSS spectroscopy. Additionally, we have
gathered older/newer spectral epochs from all the available SDSS data releases
to make the database more complete. We use PyQSOFit and perform a homogeneous
spectral decomposition of all of our SDSS spectra and tabulate the AGN
continuum and emission-line properties per epoch per source, chronologically.
This further allows us to categorize the sources in our sample as Turn-On or
Turn-Off and subsequently check for repeated occurrences of such phases. We
then estimate the black hole mass (M$_{rm BH}$) and the Eddington ratio
($lambda_{rm Edd}$) per epoch per source where the required parameters are
available and well-estimated. We realize the movement of the source in the
M$_{rm BH}$-$lambda_{rm Edd}$ plane allowing us to check for systematic
changes in the source’s fundamental properties. We then track their transition
along the optical plane of the Eigenvector 1 (EV1) schema and categorize
sources that either stay within the same Population (A or B) or make an
inter-population movement as a function of spectral epoch. We also test the
Balmer decrement (H$alpha$/H$beta$) of a subset of our sample of CL AGNs as a
function of time and AGN luminosity.
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