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

TL;DR

This study tests the CHAR model of quasar UV/optical variability using SDSS data, showing it can reproduce observed light curve features and providing insights into quasar properties like bolometric correction.

Contribution

The paper demonstrates that the CHAR model can accurately simulate quasar variability without fine-tuning and offers a method to infer quasar physical parameters from light curves.

Findings

CHAR model reproduces observed variability structure functions.

Constant bolometric correction is favored over luminosity-dependent correction.

Model enables extraction of quasar properties from light curves.

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 ($M_{\mathrm{BH}}$) 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 different $M_{\mathrm{BH}}$, $L$, 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.