A Strong X‐Ray Flux Ratio Anomaly in the Quadruply Lensed Quasar PG 1115+080

PG 1115+080 is a quadruply lensed quasar at z=1.72 whose image positions arewell fit by simple models of the lens galaxy (at z=0.31). At opticalwavelengths, the bright close pair of images exhibits a modest flux ratioanomaly (factors of ~1.2-1.4 over the past 22 years) with respect to these samemodels. We show here that as observed in X-rays with Chandra, the flux ratioanomaly is far more extreme, roughly a factor of 6. The contrasting flux ratioanomalies in the optical and X-ray band confirm the microlensing hypothesis andset a lower limit on the size of the optical continuum emission region that is\~10-100 times larger than expected from a thin accretion disk model.Comment: 6 pages, slightly revised, accepted to Ap