Deharveng, Jean-Michel and Small, Todd and Barlow, Tom A. and Péroux, Céline and Milliard, Bruno and Friedman, Peter G. and Martin, D. Christopher and Morrissey, Patrick and Schiminovich, David and Forster, Karl and Seibert, Mark and Wyder, Ted K. and Bianchi, Luciana and Donas, Jose and Heckman, Timothy M. and Lee, Young-Wook and Madore, Barry F. and Neff, Susan G. and Rich, R. Michael and Szalay, Alex S. and Welsh, Barry Y. and Yi, Sukyoung K. (2008) Ly alpha-emitting galaxies at 0.2 < z < 0.35 from GALEX spectroscopy. Astrophysical Journal, 680 (2). pp. 1072-1082. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:DEHapj08
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We have used the GALEX (Galaxy Evolution Explorer) spectroscopic survey mode, with a resolution of similar to 8 angstrom in the far-ultraviolet (FUV; 1350-1750 angstrom) and similar to 20 angstrom in the near-ultraviolet (NUV; 1950-2750 angstrom) for a systematic search of Ly alpha-emitting galaxies at low redshift. Our aim is to fill a gap between high-redshift surveys and a small set of objects studied in detail in the nearby universe. A blind search of 7018 spectra extracted in five deep exposures (5.65 deg(2)) has resulted in 96 Ly alpha-emitting galaxy candidates in the FUV domain after accounting for broad-line AGNs. The Ly alpha equivalent widths (EWs) are consistent with stellar population model predictions and show no trends as a function of UV color or UV luminosity, with the exception of a possible decrease in the most luminous objects that may be due to small-number statistics. The objects' distribution in EW is similar to that at z similar to 3, but their fraction among star-forming galaxies is smaller. Avoiding uncertain candidates, a subsample of 66 objects in the range 0.2 < z < 0.35 has been used to build a Ly alpha luminosity function (LF). The incompleteness due to objects with significant Ly alpha emission but a UV continuum too low for spectral extraction has been evaluated. A comparison with H alpha LFs in the same redshift domain is consistent with an average Ly alpha/H alpha of similar to 1 in about 15% of the star-forming galaxies. A comparison with high-redshift Ly alpha LFs implies an increase of the Ly alpha luminosity density by a factor of about 16 from z similar to 0.3 to z similar to 3. By comparison with the factor of 5 increase in the UV luminosity density in the same redshift range, this suggests an increase of the average Ly alpha escape fraction with redshift.
|Additional Information:||© 2008 The American Astronomical Society. Received 2007 November 5; accepted 2008 March 1. GALEX (Galaxy Evolution Explorer) is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASA’s support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d’Etudes Spatiales of France and the Korean Ministry of Science and Technology. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.|
|Group:||Space Radiation Laboratory|
|Subject Keywords:||galaxies: evolution; galaxies: ISM; galaxies: luminosity function, mass function; galaxies: starburst; ultraviolet: galaxies|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||03 Dec 2008 22:31|
|Last Modified:||04 Mar 2013 18:09|
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