A blind H I mass function from the Arecibo Ultra-Deep Survey (AUDS)
Abstract
The Arecibo Ultra-Deep Survey (AUDS) combines the unique sensitivity of the telescope with the wide field of the Arecibo L-band Feed Array (ALFA) to directly detect 21 cm H I emission from galaxies at distances beyond the local Universe bounded by the lower frequency limit of ALFA (z = 0.16). AUDS has collected 700 h of integration time in two fields with a combined area of 1.35 deg2. In this paper, we present data from 60 per cent of the total survey, corresponding to a sensitivity level of 80 μJy. We discuss the data reduction, the search for galaxies, parametrization, optical identification and completeness. We detect 102 galaxies in the mass range of log (M_{H I}/M)-2log h=5.6-10.3. We compute the H I mass function (HIMF) at the highest redshifts so far measured. A fit of a Schechter function results in α = - 1.37 ± 0.03, Φ* = (7.72 ± 1.4) × 10-3 h3 Mpc-3 and log (M_{H I}^{*}/M_{⊙})=({9.75± 0.041})+2 log h. Using the measured HIMF, we find a cosmic H I density of Ω _{H I}=({2.33± 0.07})× 10^{-4} h^{-1} for the sample (z = 0.065). We discuss further uncertainties arising from cosmic variance. Because of its depth, AUDS is the first survey that can determine parameters for the HIMF in independent redshift bins from a single homogeneous data set. The results indicate little evolution of the comoving mass function and Ω_{H I} within this redshift range. We calculate a weighted average for Ω_{H I} in the range 0 < z < 0.2, combining the results from AUDS as well as results from other 21 cm surveys and stacking, finding a best combined estimate of Ω_{H I}=( 2.63± 0.10)× 10^{-4} h^{-1}.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 2015
- DOI:
- 10.1093/mnras/stv1084
- arXiv:
- arXiv:1506.05931
- Bibcode:
- 2015MNRAS.452.3726H
- Keywords:
-
- galaxies: evolution;
- galaxies: ISM;
- galaxies: luminosity function;
- mass function;
- radio lines: galaxies;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 18 pages, 18 figures. Accepted for publication in MNRAS