ABSTRACT

Using the VLA in A-configuration we have obtained λ21cm absorption spectra of 12 Seyfert galaxies with bright, extended continuum radio emission. Currently, we have completed the data reduction for three galaxies: NGC 1068, Markarian 3, and NGC 3079. No absorption is detected in Mrk 3, but multiple and broad absorption lines were detected in NGC 1068 and NGC 3079. Here we present the preliminary analysis for these galaxies.

NGC 1068

The radio continuum emission from NGC 1068 is dominated by a 13″ radio triple extending SW–NE (e.g., Wilson and Ulvestad 1987). We have detected HI absorption over the entire SW radio lobe and the southern half of the central source. Three kinematically distinct regions are apparent: the radio nucleus, the linear radio structure 1–2″ SW of the nucleus (the SW “jet”), and the SW radio lobe. Using the technique of Dickey, Brinks, and Puche (1992), we extracted optical depth spectra for each of these regions (Fig. 1). Broad (FWHM = 130 ± 25 km s-1), double absorption lines are present in the nuclear region. Adopting usys(HI)= 1137 km s-1 (de Vaucouleurs et al. 1991, RC3), the lines are offset by +55 ± 11 and -283 ±11 km s-1. We suspect that these lines may arise in a region of rapid rotation and streaming near the active nucleus. In the SW “jet” multiple absorption lines centered at usys are apparent. Since this region lies along the 2.2 μm stellar bar (Thronson et al. 1989), these multiple absorption lines may be due to gas streaming in the bar potential.