Modeling Quasar UV/Optical Variability with the Corona-heated Accretion-disk Reprocessing (CHAR) Model

ABSTRACT: The rest-frame UV/optical variability of the quasars in the Sloan Digital Sky Survey (SDSS) Stripe 82 is used to test the Corona-Heated Accretion-disk Reprocessing (CHAR) model of Sun et al. (2020). We adopt our CHAR model and the observed black-hole masses (MBH) and luminosities (L) to generate mock light curves that share the same measurement noise and sampling as the real observations. Without any fine-tuning, our CHAR model can satisfactorily reproduce the observed ensemble structure functions for differentMBH, L, and rest-frame wavelengths. Our analyses reveal that a luminosity-dependent bolometric correction is disfavored over the constant bolometric correction for UV/optical luminosities. Our work demonstrates the possibility of extracting quasar properties (e.g., the bolometric correction or the dimensionless viscosity parameter) by comparing the physical CHAR model with quasar light curves.

Authors: MOUYUAN SUN, YONGQUAN XUE, HENGXIAO GUO, JUNXIAN WANG, W. N. BRANDT, JONATHAN R. TRUMP, ZHICHENG HE, TONG LIU, JIANFENG WU, AND HAIKUN LI

arXiv Link.

Figure. The ensemble structure functions at t = 30 days as a function of L3000 for the four wavelength cases. The purple, blue, green, and red squares represent the 1900 °A, 2400 °A, 3180 °A, and 4150 °A cases, respectively. The black solid (cyan dashed) curves and shaded regions correspond to the mean and 1 uncertainties of the model I (II) results. Note that the model I ensemble structure function for the 1900 °A case (i.e., the purple dotted curve) is shown in every panel for the purpose of comparison. The complete figure set (three images) is available in the online journal.