Number counts of galex sources in far-ultraviolet (1530 Å) and near-ultraviolet (2310 Å) bands

C. Kevin Xu, Jose Donas, Stephane Arnouts, Ted K. Wyder, Mark Seibert, Jorge Iglesias-Páramo, Jeremy Blaizot, Todd Small, Bruno Milliard, David Schiminovich, D. Christopher Martin, Tom A. Barlow, Luciana Blanchi, Yong Ik Byun, Karl Forster, Peter G. Friedman, Timothy M. Heckman, Patrick N. Jelinsky, Young Wook Lee, Barry F. MadoreRoger F. Malina, Patrick Morrissey, Susan G. Neff, R. Michael Rich, Oswald H.W. Siegmund, Alex S. Szalay, Barry Y. Welsh

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Abstract

Number counts of galaxies in two Galaxy Evolution Explorer (GALEX) bands [far-UV (FUV: 1530 A) and near-UV (NUV: 2310 Å); both in AB magnitudes] are reported. They provide for the first time in the literature homogeneously calibrated number counts of UV galaxies continuously covering a very wide range in UV magnitude (14-23.8). Both the FUV and NUV counts are inconsistent with a nonevolution model, whereas they are in good agreement with evolution models (essentially luminosity evolution) derived from the high-z UV luminosity functions of Arnouts et al. We find that the contribution from GAZLEX-detected galaxies to the UV background is 0.68 ± 0.10 nW m-2 sr -1 at 1530 Å and 0.99 ± 0.15 nW m-2 sr -1 at 2310 Å. These are 66% ± 9% and 44% ± 6% of the total contributions of galaxies to the UV background at 1530 Å (1.03 ± 0.15 nW m-2 sr-1) and at 2310 A (2.25 ± 0.32 nW m-2 sr-1). respectively, as estimated using the evolution models. Galaxy counts and star counts in seven regions, each containing a few square degrees of GALEX coverage in an area of ∼4-13 deg2, are compared with each other to study the region-by-region variance. This shows that for the galaxy counts, the cosmic variance is comparable to the net error due to other uncertainties. The star counts increase with decreasing absolute Galactic latitude |b|.

Original languageEnglish
Pages (from-to)L11-L14
JournalAstrophysical Journal
Volume619
Issue number1 II
DOIs
Publication statusPublished - 2005 Jan 20

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Xu, C. K., Donas, J., Arnouts, S., Wyder, T. K., Seibert, M., Iglesias-Páramo, J., Blaizot, J., Small, T., Milliard, B., Schiminovich, D., Martin, D. C., Barlow, T. A., Blanchi, L., Byun, Y. I., Forster, K., Friedman, P. G., Heckman, T. M., Jelinsky, P. N., Lee, Y. W., ... Welsh, B. Y. (2005). Number counts of galex sources in far-ultraviolet (1530 Å) and near-ultraviolet (2310 Å) bands. Astrophysical Journal, 619(1 II), L11-L14. https://doi.org/10.1086/425252