The Arecibo Galaxy Environment Survey IX: the isolated galaxy sample

0471863 - ASÚ 2017 RIV GB eng J - Journal Article
Minchin, R.F. - Auld, R. - Davies, J.I. - Karachentsev, I.D. - Keenan, O. - Momjian, E. - Rodriguez, R. - Taber, T. - Taylor, Rhys
The Arecibo Galaxy Environment Survey IX: the isolated galaxy sample.
Monthly Notices of the Royal Astronomical Society. Roč. 455, č. 4 (2016), s. 3430-3435. ISSN 0035-8711. E-ISSN 1365-2966
R&D Projects: GA MŠMT LG14013; GA ČR GAP209/12/1795
Institutional support: RVO:67985815
Keywords : individual galaxies NGC 1156 * individual galaxies NGC 5523 * individual galaxies UGC 2082
Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics
Impact factor: 4.961, year: 2016

We have used the Arecibo L-band Feed Array (ALFA) to map three regions, each of 5 deg(2), around the isolated galaxies NGC 1156, UGC 2082, and NGC 5523. In the vicinity of these galaxies we have detected two dwarf companions: one near UGC 2082, previously discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey, and one near NGC 1156, discovered by this project and reported in an earlier paper. This is significantly fewer than the 15.4(-1.5)(+1.7) that would be expected from the field HI mass function from ALFALFA or the 8.9 +/- 1.2 expected if the H I mass function from the Local Group applied in these regions. The number of dwarf companions detected is, however, consistent with a flat or declining H I mass function as seen by a previous, shallower, H I search for companions to isolated galaxies. We attribute this difference in H I mass functions to the different environments in which they are measured. This agrees with the general observation that lower ratios of dwarf to giant galaxies are found in lower density environments.
Permanent Link: http://hdl.handle.net/11104/0269222