2015/02/02 by J. Jiménez-Vicente, Jiménez-Vicente, J., E. Mediavilla +5
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.1502.00394
openalex publication_date 2015/02/02 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
We use X-ray and optical microlensing measurements to study the shape of the dark matter density profile in the lens galaxies and the size of the (soft) X-ray emission region. We show that single epoch X-ray microlensing is sensitive to the source size. Our results, in good agreement with previous estimates, show that the size of the X-ray emission region scales roughly linearly with the black hole mass, with a half light radius of R1/2≃(24±14) rg where rg=GMBH/c2. This corresponds to a size of log(R1/2/cm)=15.6+0.3-0.3 or ∼ 1 light day for a black hole mass of MBH=109 M_\sun. We simultaneously estimated the fraction of the local surface mass density in stars, finding that the stellar mass fraction is α=0.20±0.05 at an average radius of ∼ 1.9 Re, where Re is the effective radius of the lens. This stellar mass fraction is insensitive to the X-ray source size and in excellent agreement with our earlier results based on optical data. By combining X-ray and optical microlensing data, we can divide this larger sample into two radial bins. We find that the surface mass density in the form of stars is α=0.31±0.15 and α=0.13±0.05 at (1.3±0.3) Re and (2.3±0.3) Re, respectively, in good agreement with expectations and some previous results.