Oral Presentation
Probing the AGN structure using quasar variability combined with spectroscopic data
Presenter: Ji-Jia Tang (Ehime University)
Quasar variability is powerful to study the accretion disk in the AGN. The variability structure function analysis of the most luminous quasars reveals that their variability follows a universal relation, indicating that the magneto-rotational instability in the thin disk model drives their variability. On the other hand, the continuum reverberation mapping (RM) technique shows that the accretion disk is a couple of times larger than the thin disk model’s expectation. Hitherto, supermassive black hole (SMBH) mass’s effect in these results is limited, which is actually expected by the thin disk model. If the sample’s SMBH mass goes 1dex lower, we can examine not only the mass effect based on the thin disk model but also whether the thin disk is applicable at that mass (or Eddington ratio) regime. Furthermore, there is evidence showing that the AGN emission lines are related to the variability. The quasar CIV blueshifts and H-beta FWHM are both functions of deviation from the universal variability relation. Extremely high-CIV blueshift quasars are less variable, and lower CIV blueshift quasars have longer time lags in the RM. PFS will provide a new sample of quasars with wider luminosity, Eddington ratio, and SMBH mass coverages. By using LSST data, we can study their variability relation for these physical properties, in combination with their dependence on different emission lines’ properties. While low redshift (z ~< 3) samples provide wider parameter coverages, high redshift (z >~ 3) samples give higher cadence at short timescale regime, which is so far loosely constrained.
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