Optical and Near-infrared Continuum Emission Region Size Measurements in the Lensed Quasar FBQ J0951+2635

Abstract

We present 10 seasons of Sloan Digital Sky Survey r -band monitoring observations and five seasons of H -band observations of the two-image system FBQ J0951+2635 from the Kaj Strand Astrometric Reflector at the United States Naval Observatory, Flagstaff Station. We supplement our light curves with six seasons of monitoring data from the literature to yield a 10 + 6 season combined data set, which we analyzed with our Monte Carlo microlensing analysis routine to generate constraints on the structure of this system’s continuum emission source and the properties of the lens galaxy. Complementing our optical light curves with the five-season near-infrared light curves, we ran a joint Monte Carlo analysis to measure the size of the continuum emission region at both wavelengths, yielding log( r _1/2 cm ^−1 ) = ${16.24}_{-0.36}^{+0.33}$ in the r band and ${17.04}_{-0.30}^{+0.26}$ in the H band at rest wavelengths of 2744 and 7254 Å, respectively, correcting for an assumed inclination angle of 60°. Modeling the accretion disk temperature profile as a power law T ( r ) ∝ r ^− ^β , we successfully constrain the slope for FBQ J0951+2635 to $\beta ={0.50}_{-0.18}^{+0.50}$ , shallower than, but nominally consistent with, the predictions of standard thin-disk theory, β = 0.75.

Keywords

• Quasars
• Gravitational lensing
• Gravitational microlensing
• Quasar microlensing