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, Hi 21 cm emission maps, and low-resolution optical spectra of the nearby galaxy ESO 1327-2041, which is located 38′ (14 h 70-1 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 Hii regions in this arm located ∼5′ from the quasar position (∼2 h 70-1 kpc in projection) and our ground-based Hα images reveal the presence of several additional Hii regions in an inclined disk near the galaxy's center. Absorption associated with ESO 1327-2041 is found in Hi 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 Hi 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 Hi 21 cm absorbers suggests that the standard view of high-redshift damped Lyα absorbers is oversimplified in many cases. © 2011. The American Astronomical Society. All rights reserved.