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The ultraviolet colours and dust attenuation of Lyman-break galaxies

Abstract : Using a published model of galaxy formation set in the LCDM cosmology, we study the rest-frame ultraviolet (UV) colours of Lyman-break galaxies (LBGs) in the redshift range 2.5 < z < 10. The impact of dust on UV luminosity can be dramatic. The galaxy formation model calculates the dust attenuation in a self consistent way, based on a radiative transfer model. We find that intrinsically brighter galaxies suffer stronger dust attenuation than fainter ones, though the relation has a large scatter. The model predicts galaxies with UV colours consistent with the colour selection regions designed observationally to select LBGs. We find that the drop-out technique that selects LBGs based on two rest-frame UV colours is robust and effective, selecting more than 70 per cent of bright galaxies at a given redshift. We investigate the impact on the predicted UV colours of varying selected model parameters. We find that the UV colours are most sensitive to the modelling of dust attenuation and, in particular, to the extinction curve used in the radiative transfer calculation. If we assume a Milky Way (MW) dust extinction curve, the predicted UV continuum slopes are, in general, bluer than observed. However, we find that the opposite is true when using the Small Magellanic Cloud (SMC) dust extinction curve. This shows the strong dependence of UV colours on dust properties and stresses the difficulty of using the UV continuum slope as a tracer of dust attenuation without any further knowledge of the dust characteristics and distribution in high redshift galaxies
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http://hal.in2p3.fr/in2p3-00865338
Contributor : Danielle Cristofol <>
Submitted on : Tuesday, September 24, 2013 - 2:48:12 PM
Last modification on : Thursday, January 18, 2018 - 2:28:44 AM

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V. Gonzalez-Perez, C. G. Lacey, C. M. Baugh, C. S. Frenk, S. M. Wilkins. The ultraviolet colours and dust attenuation of Lyman-break galaxies. Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2013, 429, pp.1609-1625. ⟨10.1093/mnras/sts446⟩. ⟨in2p3-00865338⟩

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