February 2-5, 2021

Oral Presentation

The Correlation between Broad Absorption Line Variability and Quasar Properties

Author(s): Takashi Horiuchi (NAOJ), Tomoki Morokuma (The University of Tokyo), Toru Misawa (Shinshu University), Hidekazu Hanayama (NAOJ), and Toshihiro Kawaguchi (Onomichi City University)

Presenter: Takashi Horiuchi (Ishigakijima Astronomical Observatory/NAOJ)

Quasar outflows ejected from their accretion disk are thought to have following important
roles: (1) they eject angular momentum from the accretion disk, (2) they carry large amount
of metal and energy, consequently contributing to the chemical evolution of the host galaxy.
Quasar outflows are detected as intrinsic quasar absorption lines in the rest-frame UV spectra.
Particularly, broad absorption lines (BALs) present remarkably wide widths with FWHMs > 2,000 km/s.
BALs are known to vary in their depths, widths, and velocities within days to years.
One of the most promising scenario of BAL variability is changing ionization states in the
outflows triggered by UV flux variability of quasars. However, it is not well studied how BAL
variability amplitude (or the occurrence frequency of BAL variability) and physical properties of
quasars are related. Flux variability amplitude tend to decrease with quasar luminosities and Eddington
ratios, while increases with blackhole masses. If the variability of BAL equivalent widths (EWs) is
sensitive to flux variability of quasar, that would correlate with these physical properties.
We investigate the correlation between variability amplitude of CIV BAL EWs and
quasar luminosities, blackhole masses, Eddington ratios, and accretion disk temperature. In order to
probe these relations, we use the BAL EW data sets of 25 BAL quasars taken by the SDSS Reverberation
Mapping project. As a result, there are a strong negative (or moderate positive) correlation between the
variability amplitude and Eddington ratios and accretion disk temperature (or blackhole mass).
The fact suggests that the behavior of quasar outflows and the physical properties of quasars are
closely related.

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