AAS 195th Meeting, January 2000
Session 17. Quasars, QSO's and Their Environments
Display, Wednesday, January 12, 2000, 9:20am-6:30pm, Grand Hall

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[17.08] Keck I Images of the Einstein Cross QSO: Infrared Emission is due to Dust

E. Agol (JHU), B. Jones (UCSD), O. M. Blaes (UCSB)

We present images of the Einstein Cross gravitationally lensed quasar (Q2237+0305, z=1.67) at 8.9 and 11.7 microns taken with the Long Wavelength Spectrometer on Keck I with ~ 0.25 arcsecond resolution (Jones & Puetter 1993). We find that the flux ratios of the four mid- infrared images differ from the optical image ratios, while they agree with the flux ratios observed in the radio and predicted by gravitational lens models of the lens galaxy (z=0.04). Our observations indicate that the infrared emission region is more extended than an Einstein radius due to an average stellar mass, ~1017 cm, as is predicted by dust emission models. This rules out synchrotron emission as being responsible for the infrared spectral component, as this would predict flux ratios similar to the optical, since both the optical and synchrotron emission regions should be comparable in size. The 8.9/11.7 colors of the four images are identical and the optical to infrared slope is consistent with that of an average QSO. We also discuss the differential extinction due to the lens galaxy.

The author(s) of this abstract have provided an email address for comments about the abstract: agol@pha.jhu.edu

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