2008/02/29 by Christopher W. Morgan, C. S. Kochanek, Christopher S. Kochanek +5
Physics and Astronomy · #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1086/592767
21 pages, 5 figures, submitted to ApJ; corrected errors with the measurement of the A1/A2 flux ratio
arxiv created 2008/04/30 · openalex publication_date 2008/11/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We analyzed the microlensing of the X-ray and optical emission of the lensed quasar PG 1115+080. We find that the effective radius of the X-ray emission is 1.3 + 1.1 −0.5 dex smaller than that of the optical emission. Viewed as a thin disk observed at inclination angle i , the optical accretion disk has a scale length, defined by the point where the disk temperature matches the rest-frame energy of the monitoring band ( kT = hc/λ rest with λ rest = 0.3 μm), of log( r s , opt /cm)[cos( i )/0.5] ½ = 16.6 ± 0.4. The X-ray emission region (1.4-21.8 keV in the rest frame) has an effective half-light radius of log ( r 1/2,X /cm) = 15.6 + 0.6 −0.9 . Given an estimated black hole mass of 1.2 × 10 9 M ☉ , corresponding to a gravitational radius of log ( r g /cm) = 14.3, the X-ray emission is generated near the inner edge of the disk, while the optical emission comes from scales slightly larger than those expected for an Eddington-limited thin disk. We find a weak trend supporting models with low stellar mass fractions near the lensed images, in mild contradiction to inferences from the stellar velocity dispersion and the time delays.