Resolving the inner accretion flow towards the central supermassive black hole in SDSS J1339+1310

TL;DR

This study investigates the structure of the accretion disk around the supermassive black hole in SDSS J1339+1310 using microlensing and spectral data, revealing the size of the emission region and black hole mass.

Contribution

First to constrain the accretion disk's half-light radius in SDSS J1339+1310 using microlensing variations and spectral analysis.

Findings

Half-light radius of the 1930 Å continuum-emitting region is approximately 10^15.4 cm.

Black hole mass estimated at about 4.0 × 10^8 solar masses.

The emission region is located only a few tens of Schwarzschild radii from the black hole.

Abstract

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 (NIR) spectra from the first 11 observational seasons after its discovery. The 2009$-$2019 light curves displayed pronounced microlensing variations on different timescales, and this microlensing signal permitted us to constrain the half-light radius of the 1930 \r{A} continuum-emitting region. Assuming an accretion disc with an axis inclined at 60 deg to the line of sight, we obtained log$_{10}$($r_{1/2}$/cm) = 15.4$^{+0.3}_{-0.4}$. We also estimated the central black hole mass from spectroscopic data. The width of the Civ, Mgii, and H$\beta$ emission lines, and the continuum luminosity at 1350, 3000, and 5100 \r{A}, led to log$_{10}$($M_{BH}$/M$_{\odot}$) = 8.6 $\pm$ 0.4. Thus, hot gas responsible for the 1930 \r{A} continuum emission is likely orbiting a 4.0 $\times$ 10$^8$ M$_{\odot}$ black hole at an $r_{1/2}$ of only a few tens of Schwarzschild radii.