The Sizes of the X-ray and Optical Emission Regions of RXJ1131-1231

Understand

We use gravitational microlensing of the four images of the z=0.658 quasar RXJ1131-1231 to measure the sizes of the optical and X-ray emission regions of the quasar.

• The (face-on) scale length of the optical disk at rest frame 400 nm is 1.3 10^15cm, while the half-light radius of the rest frame 0.3-17 keV X-ray emission is 2.3 10^14cm.
• The formal uncertainties are factors of 1.6 and 2.0, respectively.
• With the exception of the lower limit on the X-ray size, the results are very stable against any changes in the priors used in the analysis.