The Quasar/Galaxy Pair PKS 1327-206/ESO 1327-2041: Absorption Associated with a Recent Galaxy Merger

Abstract

We present HST/WFPC2 broadband and ground-based Hα images, H I 21 cm emission maps, and low-resolution optical spectra of the nearby galaxy ESO 1327-2041, which is located 38'' (14 h ^-1 ₇₀ kpc in projection) west of the quasar PKS 1327-206. Our Hubble Space Telescope (HST) images reveal that ESO 1327-2041 has a complex optical morphology, including an extended spiral arm that was previously classified as a polar ring. Our optical spectra show Hα emission from several H II regions in this arm located ~5'' from the quasar position (~2 h ^-1 ₇₀ kpc in projection) and our ground-based Hα images reveal the presence of several additional H II regions in an inclined disk near the galaxy's center. Absorption associated with ESO 1327-2041 is found in H I 21 cm, optical, and near-UV spectra of PKS 1327-206. We find two absorption components at cz _abs = 5255 and 5510 km s^-1 in the H I 21 cm absorption spectrum, which match the velocities of previously discovered metal-line components. We attribute the 5510 km s^-1 absorber to disk gas in the extended spiral arm and the 5255 km s^-1 absorber to high-velocity gas that has been tidally stripped from the disk of ESO 1327-2041. The complexity of the galaxy/absorber relationships for these very nearby H I 21 cm absorbers suggests that the standard view of high-redshift damped Lyα absorbers is oversimplified in many cases.