Conclusions

We conclude that the infrared emission in the Einstein Cross QSO is not due to synchrotron, but can be fit with a dust-reprocessing model. Monitoring at shorter wavelengths might reveal the transition from the dust emission region to the optical emission region. The optical/UV SED must be flatter than the prediction of a simple blackbody disk since the dust emission cuts off just above the sublimation temperature, and thus does not modify the optical spectrum. The flux ratios of the four images are most consistent with the SWL model , but better signal-to-noise observations might lead to a better constraint. The infrared SED of the Einstein Cross is unusual, but not unphysical. It is consistent with an archival ISO spectrum, but would be an interesting target for the SIRTF satellite. Observations at 20 m and 5m would give better constraints on the dust emission model.

© Copyright Astronomical Society of Australia 1997