Abstract
We report the first polarimetric observations in the ultraviolet of two AGN's, the blazar BL Lac and the gravitational lens candidate Q2345+007. We find strong (p>3%) and variable UV polarization in BL Lac, two of the characteristics exhibited by blazars in the visible. The polarization of BL Lac in the UV decreased significantly (from 18% to <5%) over a timescale of days. The flux density in the polarimetric bandpass showed changes which were not correlated with the polarimetric changes. The behavior of BL Lac in the UV is consistent with the two-component model of its polarized flux proposed by Brindleet al. (1985). The UV properties of the images in the Q2345+007 system are consistent with a gravitational lens interpretation. The QSO imaged in Q2345+007A is an excellent candidate to monitor for variable polarization on a timescale of weeks. Detecting the same polarimetric variation in each image of a gravitational lens may be the most effective method of determining the time-of-flight difference between the two image paths.
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Based in part on observations with the Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by AURA, Inc. under NASA contract NAS 5-26555.
also Universities Space Research Association.
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Dolan, J.F., Boyd, P.T., Nelson, M.J. et al. Hubble space telescope observations of AGN's in the ultraviolet: BL Lac and Q2345+007. Astrophys Space Sci 240, 295–303 (1996). https://doi.org/10.1007/BF00639593
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DOI: https://doi.org/10.1007/BF00639593