Probing the dark matter radial profile in lens galaxies and the size of X-ray emitting region in quasars with microlensing

Understand

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 $R_{1/2}\simeq(24\pm14) r_g$ where $r_g=GM_{BH}/c^2$.
• This corresponds to a size of $\log(R_{1/2}/cm)=15.6^{+0.3}_{-0.3}$ or $\sim$ 1 light day for a black hole mass of $M_{BH}=10^9 M_\sun$.