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 β = 0.50 − 0.18 + 0.50 , shallower than, but nominally consistent with, the predictions of standard thin-disk theory, β = 0.75.

Accretion Disk Size and Updated Time-delay Measurements in the Gravitationally Lensed Quasar SDSS J165043.44+425149.3

“…In Figure 9 we display the quasar accretion disk size-black hole mass relation (Morgan et al 2010(Morgan et al , 2018 with the present SDSS1650 measurement shown in blue and updated measurements included for the quasars SBS0909+532, Q0957+561, and FBQ0951+2635 using the values from and Rivera et al (2023). Not only is our new SDSS1650 measurement fully consistent with the relation, but it represents the most massive black hole studied with the multiepoch microlensing technique.…”

“…SDSS1650 is yet another system in which the microlensing size measurement is larger than that predicted by standard disk theory. Further evidence of this discrepancy is shown in Rivera et al (2023) and the references therein, who showed that the temperature profiles calculated via gravitational lensing are shallower than expected from the Shakura & Sunyaev (1973) model.…”

“…When we tested for this possibility by rerunning the simulations including 30% flux contamination from the BLR, our results remained consistent. See Rivera et al (2023) for further discussion on the likelihood and limitations of BLR contamination biasing multiepoch microlensing results.…”