Journal Article

Predictions for the intrinsic UV continuum properties of star-forming galaxies and the implications for inferring dust extinction

Stephen M. Wilkins, Violeta Gonzalez-Perez, Cedric G. Lacey and Carlton M. Baugh

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 424, issue 2, pages 1522-1529
Published in print August 2012 | ISSN: 0035-8711
Published online August 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21344.x
Predictions for the intrinsic UV continuum properties of star-forming galaxies and the implications for inferring dust extinction

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Abstract

The observed ultraviolet continuum (UVC) slope is potentially a powerful diagnostic of dust obscuration in star-forming galaxies. However, the intrinsic slope is also sensitive to the form of the stellar initial mass function and to the recent star formation and metal enrichment histories of a galaxy. Using the galform semi-analytical model of galaxy formation, we investigate the intrinsic distribution of UVC slopes. For star-forming galaxies, we find that the intrinsic distribution of UVC slopes at z= 0, parametrized by the power-law index β, has a standard deviation of σβ≃ 0.30. This suggests an uncertainty on the inferred ultraviolet (UV) attenuation of Afuv≃ 0.7 (assuming a Calzetti attenuation curve) for an individual object, even with perfect photometry. Furthermore, we find that the intrinsic UVC slope correlates with star formation rate, intrinsic UV luminosity, stellar mass and redshift. These correlations have implications for the interpretation of trends in the observed UVC slope with these quantities irrespective of the sample size or quality of the photometry. Our results suggest that in some cases the attenuation by dust has been incorrectly estimated.

Keywords: galaxies: formation; ultraviolet: galaxies

Journal Article.  5466 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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