Journal Article

GAMA/H-ATLAS: the ultraviolet spectral slope and obscuration in galaxies

D. B. Wijesinghe, E. da Cunha, A. M. Hopkins, L. Dunne, R. Sharp, M. Gunawardhana, S. Brough, E. M. Sadler, S. Driver, I. Baldry, S. Bamford, J. Liske, J. Loveday, P. Norberg, J. Peacock, C. C. Popescu, R. Tuffs, E. Andrae, R. Auld, M. Baes, J. Bland-Hawthorn, S. Buttiglione, A. Cava, E. Cameron, C. J. Conselice, A. Cooray, S. Croom, A. Dariush, G. DeZotti, S. Dye, S. Eales, C. Frenk, J. Fritz, D. Hill, R. Hopwood, E. Ibar, R. Ivison, M. Jarvis, D. H. Jones, E. van Kampen, L. Kelvin, K. Kuijken, S. J. Maddox, B. Madore, M. J. Michałowski, B. Nichol, H. Parkinson, E. Pascale, K. A. Pimbblet, M. Pohlen, M. Prescott, G. Rhodighiero, A. S. G. Robotham, E. E. Rigby, M. Seibert, S. Sergeant, D. J. B. Smith, P. Temi, W. Sutherland, E. Taylor, D. Thomas and P. van der Werf

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 415, issue 2, pages 1002-1012
Published in print August 2011 | ISSN: 0035-8711
Published online July 2011 | e-ISSN: 1365-2966 | DOI:
GAMA/H-ATLAS: the ultraviolet spectral slope and obscuration in galaxies

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We use multiwavelength data from the Galaxy And Mass Assembly (GAMA) and Herschel-ATLAS (H-ATLAS) surveys to compare the relationship between various dust obscuration measures in galaxies. We explore the connections between the ultraviolet (UV) spectral slope, β, the Balmer decrement and the far-infrared (FIR) to 150 nm far-ultraviolet (FUV) luminosity ratio. We explore trends with galaxy mass, star formation rate (SFR) and redshift in order to identify possible systematics in these various measures. We reiterate the finding of other authors that there is a large scatter between the Balmer decrement and the β parameter, and that β may be poorly constrained when derived from only two broad passbands in the UV. We also emphasize that FUV-derived SFRs, corrected for dust obscuration using β, will be overestimated unless a modified relation between β and the attenuation factor is used. Even in the optimum case, the resulting SFRs have a significant scatter, well over an order of magnitude. While there is a stronger correlation between the IR-to-FUV luminosity ratio and β parameter than with the Balmer decrement, neither of these correlations are particularly tight, and dust corrections based on β for high-redshift galaxy SFRs must be treated with caution. We conclude with a description of the extent to which the different obscuration measures are consistent with each other as well as the effects of including other galactic properties on these correlations.

Keywords: galaxies: evolution; galaxies: formation; galaxies: general

Journal Article.  7210 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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