Mid-Infrared Imaging of the Einstein Cross QSO

Abstract

Received 2001 January 21, accepted 2001 March 7

Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >10¹⁷ cm, ruling out synchrotron models, but consistent with dust emission models. Other constraints rule out starburst models. The flux ratios greatly constrain the lens model.