Showing papers by "Stephen E. Schneider published in 2007"
TL;DR: In this article, 21 cm HI line observations of 5x1 square degrees centered on the local Abell cluster 1367 obtained as part of the Arecibo Galaxy Environment Survey are presented.
Abstract: We present 21 cm HI line observations of 5x1 square degrees centered on the local Abell cluster 1367 obtained as part of the Arecibo Galaxy Environment Survey. One hundred sources are detected (79 new HI measurements and 50 new redshifts), more than half belonging to the cluster core and its infalling region. Combining the HI data with SDSS optical imaging we show that our HI selected sample follows scaling relations similar to the ones usually observed in optically selected samples. Interestingly all galaxies in our sample appear to have nearly the same baryon fraction independently of their size, surface brightness and luminosity. The most striking difference between HI and optically selected samples resides in their large scale distribution: whereas optical and X-ray observations trace the cluster core very well, in HI there is almost no evidence of the presence of the cluster. Some implications on the determination of the cluster luminosity function and HI distribution for samples selected at different wavelength are also discussed.
49 citations
TL;DR: NIBLES as mentioned in this paper is a key project proposed for the 100m-class Nancay Radio Telescope (NRT) in France, whose aim is a census of the HI gas content and dynamics of 4,000 Sloan Digital Sky Survey galaxies in the Local Volume (900
Abstract: NIBLES is a Key Project proposed for the 100m-class Nancay Radio Telescope (NRT) in France. Its aim is a census of the HI gas content and dynamics of 4,000 Sloan Digital Sky Survey galaxies in the Local Volume (900
1 citations
01 Jun 2007
TL;DR: In this paper, the authors review the history of blind HI surveys and the evidence for cosmic variance in the HI mass function and suggest that there are locales where dark (or dim) HI-rich galaxies are more likely to be found.
Abstract: I review the history of blind HI surveys and the evidence for cosmic variance in the HI mass function. Even the most sensitive current surveys are challenged by noise levels that make determining the shape of the mass function difficult, and this can lead to discrepant results. However, some differences in the mass function appear to be real environmental effects, and this suggest that there are locales where dark (or dim) HI-rich galaxies are more likely to be found. The requirements for significantly deeper surveys beyond the local supercluster to sample cosmic variance in a wider variety of environoments are modeled and discussed.
1 citations
01 Jun 2007
TL;DR: The results of ALFA ZOA precursor observations on two patches of sky totaling 140 deg2 (near l = 40°, and l = 192°) were presented in this article.
Abstract: The Arecibo L-band Feed Array Zone of Avoidance Survey (ALFA ZOA) will map 1350-1800 deg2 at low Galactic latitude, providing HI spectra for galaxies in regions of the sky where our knowledge of local large scale structure remains incomplete, owing to obscuration from dust and high stellar confusion near the Galactic plane. Because of these effects, a substantial fraction of the galaxies detected in the survey will have no optical or infrared counterparts. However, near infrared follow up observations of ALFA ZOA sources found in regions of lowest obscuration could reveal whether some of these sources could be objects in which little or no star formation has taken place (“dark galaxies”). We present here the results of ALFA ZOA precursor observations on two patches of sky totaling 140 deg2 (near l = 40°, and l = 192°). We have measured HI parameters for detections from these observations, and cross-correlated with the NASA/IPAC Extragalactic Database (NED). A significant fraction of the objects have never been detected at any wavelength. For those galaxies that have been previously detected, a significant fraction have no previously known redshift, and no previous HI detection.
01 Jun 2007
TL;DR: The Arecibo Galaxy Environment Survey (AGES) as discussed by the authors is a blind neutral hydrogen survey using the ALFA multibeam receiver at arecibo Observatory to reach unprecedented sensitivities in a number of selected fields in the local Universe.
Abstract: The Arecibo Galaxy Environment Survey is a blind neutral hydrogen survey using the ALFA multibeam receiver at Arecibo Observatory to reach unprecedented sensitivities in a number of selected fields in the local Universe. When completed the survey will cover 200 square degrees out to a distance of at least 270 Mpc. If a population of gas-rich dark galaxies exists, then this survey is in a prime position to uncover that population. So far 20 square degrees have been covered in the regions of Abell 1367, the Virgo Cluster, the NGC 7332/9 galaxy pair and the isolated galaxy NGC 1156. Over 200 sources have been found, including a number that have no obvious optical counterparts. We discuss here the potential of AGES for uncovering more such objects and the characteristics of the dark sources identified to date.