Extended X-ray Monitoring of Gravitational Lenses with Chandra and Joint Constraints on X-ray Emission Regions

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We present an X-ray photometric analysis of six gravitationally lensed quasars, with observation campaigns spanning from 5 to 14 years, measuring the total (0.83 - 21.8 keV restframe), soft (0.83 - 3.6 keV), and hard (3.6 - 21.8 keV) band image flux ratios or each epoch.

• Using the ratios of the model-predicted macro-magnifications as baselines, we build differential microlensing light curves and obtain joint likelihood functions for the average X-ray emission region sizes.
• Our analysis yields a Probability Distribution Function for the average half-light radius of the X-Ray emission region in the sample that peaks slightly above 1 gravitational radius and with nearly indistinguishable 68% confidence (one-sided) upper limits of 17.8 and 18.9 gravitational radii for the soft and hard X-ray emitting regions, assuming a mean stellar mass of 0.3 solar masses.
• We see hints of energy dependent microlensing between the soft and hard bands in two of the objects.