VLA detection of OH absorption from the elliptical galaxy NGC 1052

Abstract

VLA observations of OH absorption towards the elliptical galaxy NGC 1052 are presented. Both OH lines, at 1665 and 1667 MHz, were detected in absorption towards the center of NGC 1052. The hyperfine ratio of the two OH lines ($\tau$${}_{1667}$/$\tau$${}_{1665}$) is 2.6$\pm$0.8 as compared to 1.8 expected for the excitation under LTE conditions for an optically thin cloud. The column density of OH is estimated to be $2.73(\pm 0.26)\times 10^{14}c{m}^{-2}$ assuming $T_{ex}\sim$10 K. The centers of both the OH lines are redshifted from the systemic velocity of the galaxy by $\sim$173 km s${}^{-1}$. The velocity of OH line coincides with the velocity corresponding to the strongest HI absorption. We suggest that OH absorption is arising from a molecular cloud falling towards the nucleus. The OH line, though narrower, is found to be within the much broader and smoother H${}_2$O megamaser emission. The possible link between OH/HI and $H_{2}O$ emission is discussed.

4 pages, 2 figures; Accepted for publication in A&A Letter

References in corpus (4)

• Enhanced OH in C-type shock waves in molecular clouds
• Neutral Hydrogen (21 cm) Absorption in Seyfert Galaxies: Evidence for Free-free Absorption and Sub-kiloparsec Gaseous Disks
• The Dense Plasma Torus Around the Nucleus of an Active Galaxy NGC 1052
• A Search for OH Megamasers at z > 0.1. I. Preliminary Results

Cited by in corpus (11)

• The Twin--Jet System in NGC 1052: VLBI-Scrutiny of the Obscuring Torus
• The Shroud Around the Twin Radio Jets in NGC 1052
• Positional Coincidence of H2O Maser and a Plasma Obscuring Torus in Radio Galaxy NGC 1052
• Mm-wave HCO+, HCN and CO absorption toward NGC1052
• Redshifted intergalactic 3He+ 8.7 GHz hyperfine absorption
• Spatially Resolved HCN Absorption Features in the Circumnuclear Region of NGC 1052
• Probing Jet-Torus Interaction in the Radio Galaxy NGC 1052 by Sulfur-Bearing Molecules
• A broad HCO+ absorption line associated with the circumnuclear torus of NGC 1052
• Observations of hydroxyl in early-type galaxies
• Radio continuum detection in blue early-type weak emission line galaxies
• H_2O maser and a plasma obscuring torus in the radio galaxy NGC 1052