http://arxiv.org/abs/2201.08943
We present damped harmonic oscillator (DHO) light-curve modeling for a sample of 12,714 spectroscopically confirmed quasars in the Sloan Digital Sky Survey Stripe 82 region. DHO is a second-order continuous-time autoregressive moving-average (CARMA) process, and features four independent parameters: a natural oscillation frequency ($\omega_{0}$), a damping ratio ($\xi$), a characteristic perturbation timescale ($\tau_{\mathrm{perturb}}$), and an amplitude for the perturbing white noise ($\sigma_{\mathrm{\epsilon}}$). The asymptotic variability amplitude of a DHO process is quantified by $\sigma_{\mathrm{DHO}}$ — a function of $\omega_{0}$, $\xi$, $\tau_{\mathrm{perturb}}$, and $\sigma_{\mathrm{\epsilon}}$. We found that both $\tau_{\mathrm{perturb}}$ and $\sigma_{\mathrm{\epsilon}}$ follow different dependencies with rest-frame wavelength ($\lambda_{\mathrm{RF}}$) on either side of 2500 angstroms, whereas $\sigma_{\mathrm{DHO}}$ follows a single power-law relation with $\lambda_{\mathrm{RF}}$. After correcting for wavelength dependence, $\sigma_{\mathrm{DHO}}$ exhibits anti-correlations with both the Eddington ratio and black hole mass, and $\tau_{\mathrm{perturb}}$ — with a typical value of days in rest-frame — shows an anti-correlation with the bolometric luminosity. Modeling AGN variability as a DHO offers more insight into how accretion disks work close to the supermassive black holes (SMBHs) at the center of AGN. The newly discovered short-term variability ($\tau_{\mathrm{perturb}}$) and its correlation with bolometric luminosity pave the way for new algorithms that will derive fundamental properties (e.g., Eddington ratio) of AGN using photometric data alone.
W. Yu, G. Richards, M. Vogeley, et. al.
Tue, 25 Jan 22
77/78
Comments: 25 pages, 14 figures, submitted to AAS journals