Resolving The Inner Accretion Flow Towards The Central Supermassive Black Hole In Sdss J1339+1310

We studied the accretion disc structure in the doubly imaged lensed quasar SDSS J1339+1310 using r-band light curves and UV-visible to near-IR spectra from the first 11 observational seasons after its discovery. The 2009-2019 light curves displayed pronounced microlensing variations on different timescales, and this microlensing signal permitted us to constrain the half-light radius of the 1930 angstrom continuum-emitting region. Assuming an accretion disc with an axis inclined at 60 degrees to the line of sight, we obtainedlog(r(1/2)/cm) = 15.4(-0.4)(+0.93)logr1 / 2/ cm= 15 .4- 0.4+ 0.3. We also estimated the central black hole mass from spectroscopic data. The width of the CIV, MgII, and H beta emission lines, and the continuum luminosity at 1350, 3000, and 5100 angstrom, led to log(M-BH/M-circle dot)=8.6 +/- 0.4. Thus, hot gas responsible for the 1930 angstrom continuum emission is likely orbiting a 4.0x10(8) M-circle dot black hole at an r(1/2) of only a few tens of Schwarzschild radii.