A blind HI mass function from the Arecibo Ultra-Deep Survey (AUDS)

作者：Hoppmann L^*; Staveley Smith L; Freudling W; Zwaan M A; Minchin R F; Calabretta M R

来源：Monthly Notices of the Royal Astronomical Society, 2015, 452(4): 3726-3741.

DOI：10.1093/mnras/stv1084

• galaxies: evolution
• galaxies: ISM
• galaxies: luminosity function, mass function
• radio lines: galaxies

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 HI 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 deg(2). In this paper, we present data from 60 per cent of the total survey, corresponding to a sensitivity level of 80 mu Jy. 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-HI/M) -2 log h = 5.6-10.3. We compute the HI mass HIMF) at the highest redshifts so far measured. A fit of a Schechter function results in alpha = -1.37 +/- 0.03, Phi* = (7.72 +/- 1.4) x 10(-3) h(3) Mpc(-3) and log (M-HIM-circle dot) = (9.75 +/- 0.041) + 2 log h. Using the measured HIMF, we find a cosmic HI density of Omega(HI) = (2.33 +/- 0.07) x 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 Omega(HI) within this redshift range. We calculate a weighted average for Omega(HI) 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 Omega(HI) = (2.63 +/- 0.10) x 10(-4) h(-1).

• 出版日期2015-10-1