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Session 57 - Astrophysical Diagnostics from Polarimetry.
Display session, Wednesday, June 12
IRAS 20181-2244 is part of the Boller et al. (1992) sample of bright IRAS galaxies which were also identified as soft x--ray sources by ROSAT. It was reported by Elizalde amp; Steiner (1994) to have a Seyfert 2 type spectrum and a quasar luminosity, and thus is a candidate to be one of the elusive Type 2 (narrow--line) quasars. We present imaging polarimetry, spectroscopy, and spectropolarimetry of this AGN, taken at the LNA 1.6m telescope in Brasópolis and at the CTIO 4m with a visitor polarimetry unit on the RC Spectrograph.
The polarization of the galaxy is significantly higher than that of nearby stars in the sky plane. The polarization drops to near zero at the forbidden lines of [O III] and [N II]. H\alpha and H\beta are visible in the polarized flux but do not appear significantly broader than in direct flux, as we might have seen if an obscured broad line region is present and visible only in scattered- and thus polarized- light. Spectroscopy indicates the presence of Fe II lines, confirming the result of Moran, Helfand, amp; Halpern (1996, in press) that IRAS 20181-2244 (like many other of these Boller AGNs) can be classified as I Zw I type objects.
This research is supported by grants from NSF, FAPESP, and CNPq.
Program listing for Wednesday