The Arecibo Galaxy Environment Survey III: Observations Toward the Galaxy Pair NGC 7332/7339 and the Isolated Galaxy NGC 1156

TL;DR

This survey mapped neutral hydrogen around galaxy pairs and isolated galaxies, discovering new dwarf galaxies and interaction remnants to better understand galaxy environments.

Contribution

First comprehensive HI mapping of NGC 7332/9 and NGC 1156 regions, identifying new dwarf galaxies and interaction features.

Findings

87 galaxies detected, 15 with prior redshifts

2 new dwarf galaxies near NGC 7332

1 possible dwarf galaxy near NGC 7332

Abstract

Two 5 square degree regions around the NGC 7332/9 galaxy pair and the isolated galaxy NGC 1156 have been mapped in the 21-cm line of neutral hydrogen (HI) with the Arecibo L-band Feed Array out to a redshift of ~0.065$ (~20,000$ km/s) as part of the Arecibo Galaxy Environment Survey. One of the aims of this survey is to investigate the environment of galaxies by identifying dwarf companions and interaction remnants; both of these areas provide the potential for such discoveries. The neutral hydrogen observations were complemented by optical and radio follow-up observations with a number of telescopes. A total of 87 galaxies were found, of which 39 (45 per cent) were previously cataloged and 15 (17 per cent) have prior redshifts. Two dwarf galaxies have been discovered in the NGC 7332 group and a single dwarf galaxy in the vicinity NGC 1156 . A parallel optical search of the area revealed one further possible dwarf galaxy near NGC 7332.