In this paper we describe results from the Arecibo Galaxy Environments Survey (AGES). The survey reaches column densities of ~3x10^18 cm^-2 and masses of ~10^7 M_O, over individual regions of order 10 sq deg in size, out to a maximum velocity of 18,000 km s^-1. Each surveyed region is centred on a nearby galaxy, group or cluster, in this instance the NGC7448 group. Galaxy interactions in the NGC7448 group reveal themselves through the identification of tidal tails and bridges. We find ~2.5 times more atomic gas in the inter-galactic medium than in the group galaxies. We identify five new dwarf galaxies, two of which appear to be members of the NGC7448 group. This is too few, by roughly an order of magnitude, dwarf galaxies to reconcile observation with theoretical predictions of galaxy formation models. If they had observed this region of sky previous wide area blind HI surveys, HIPASS and ALFALFA, would have detected only 5% and 43% respectively of the galaxies we detect, missing a large fraction of the atomic gas in this volume. We combine the data from this paper with that from our other AGES papers (370 galaxies) to derive a HI mass function with the following Schechter function parameters alpha=-1.52+/-0.05, M^*=5.1+/-0.3x10^9 h_72^-2 M_O, phi=8.6+/-1.1x10-3 h_72^3 Mpc^-3 dex-1. Integrating the mass function leads to a cosmic mass density of atomic hydrogen of Omega_HI=5.3+/-0.8x10^-4 h_72^-1. Our mass function is steeper than that found by both HIPASS and ALFALFA (alpha=1.37 and 1.33 respectively), while our cosmic mass density is consistent with ALFALFA, but 1.7 times larger than found by HIPASS.
Cosmic Flows is an international multi-element project with the goal to map motions of galaxies in the Local Universe. Kinematic information from observations in the radio HI line and photometry at optical or near-infrared bands are acquired to derive the large majority of distances that are obtained through the luminosity-linewidth or Tully-Fisher relation. This paper gathers additional observational radio data, frequently unpublished, retrieved from the archives of Green Bank, Parkes and Arecibo telescopes. Extracted HI profiles are consistently processed to produce linewidth measurements. O…
We measure the HI mass function (HIMF) and velocity width function (WF) across environments over a range of masses $7.2<\log(M_{HI}/M_{\odot})<10.8$, and profile widths $1.3\log(km/s)<\log(W)<2.9\log(km/s)$, using a catalog of ~7,300 HI-selected galaxies from the ALFALFA Survey, located in the region of sky where ALFALFA and SDSS (Data Release 7) North overlap. We divide our galaxy sample into those that reside in large-scale voids (void galaxies) and those that live in denser regions (wall galaxies). We find the void HIMF to be well fit by a Schechter function with normalization $Φ^*=(1.37\pm…
We present HI 21cm emission observations of the z ~ 0.00632 sub-damped Lyman-alpha absorber (sub-DLA) towards PG1216+069 made using the Arecibo Telescope and the Very Large Array (VLA). The Arecibo 21cm spectrum corresponds to an HI mass of ~ 3.2x10^7 solar masses, two orders of magnitude smaller than that of a typical spiral galaxy. This is surprising since in the local Universe the cross-section for absorption at high HI column densities is expected to be dominated by spirals. The 21cm emission detected in the VLA spectral cube has a low signal-to-noise ratio, and represents only half the to…
The Arecibo L-Band Feed Array Zone of Avoidance (ALFA ZOA) Deep Survey is the deepest and most sensitive blind Hi survey undertaken in the ZOA. ALFA ZOA Deep will cover about 300 square degrees of sky behind the Galactic plane in both the inner (30 deg < l < 75 deg; b < |2 deg|) and outer (175 deg < l < 207 deg; -2 deg < b < +1 deg) Galaxy, using the Arecibo Radio Telescope. First results from the survey have found 61 galaxies within a 15 square degree area centered on l = 192 deg and b = -2 deg. The survey reached its expected sensitivity of rms = 1 mJy at 9 km/s channel resolution, and is sh…
