The Arecibo Legacy Fast ALFA Survey: The α.40 H I Source Catalog, Its Characteristics and Their Impact on the Derivation of the H I Mass Function

Type Journal Article
Names Martha P. Haynes, Riccardo Giovanelli, Ann M. Martin, Kelley M. Hess, Amélie Saintonge, Elizabeth A. K. Adams, Gregory Hallenbeck, G. Lyle Hoffman, Shan Huang, Brian R. Kent, Rebecca A. Koopmann, Emmanouil Papastergis, Sabrina Stierwalt, Thomas J. Ba
Publication The Astronomical Journal
Volume 142
Issue 5
Pages 170
Date November 1, 2011
Short Title The Arecibo Legacy Fast ALFA Survey
Library Catalog NASA ADS
Abstract We present a current catalog of 21 cm H I line sources extracted from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey over ~2800 deg2 of sky: the α.40 catalog. Covering 40% of the final survey area, the α.40 catalog contains 15,855 sources in the regions 07h30m < R.A. < 16h30m, +04° < decl. <+16°, and +24° < decl. <+28° and 22h < R.A. < 03h, +14° < decl. <+16°, and +24° < decl. < + 32°. Of those, 15,041 are certainly extragalactic, yielding a source density of 5.3 galaxies per deg2, a factor of 29 improvement over the catalog extracted from the H I Parkes All-Sky Survey. In addition to the source centroid positions, H I line flux densities, recessional velocities, and line widths, the catalog includes the coordinates of the most probable optical counterpart of each H I line detection, and a separate compilation provides a cross-match to identifications given in the photometric and spectroscopic catalogs associated with the Sloan Digital Sky Survey Data Release 7. Fewer than 2% of the extragalactic H I line sources cannot be identified with a feasible optical counterpart; some of those may be rare OH megamasers at 0.16 < z < 0.25. A detailed analysis is presented of the completeness, width-dependent sensitivity function and bias inherent of the α.40 catalog. The impact of survey selection, distance errors, current volume coverage, and local large-scale structure on the derivation of the H I mass function is assessed. While α.40 does not yet provide a completely representative sampling of cosmological volume, derivations of the H I mass function using future data releases from ALFALFA will further improve both statistical and systematic uncertainties.
Tags Galaxies: Luminosity Function, Mass Function, Radio Lines: Galaxies, catalogs, galaxies: distances and redshifts, galaxies: spiral, surveys
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