Publication: SHARDS: constraints on the dust attenuation law of star-forming galaxies at z∼2
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We make use of the Survey of High-z Absorption Red and Dead Sources, an ultradeep (<26.5AB) galaxy survey that provides optical photospectra at resolution R similar to 50, via medium-band filters (FWHM similar to 150 angstrom). This data set is combined with ancillary optical and NIR fluxes to constrain the dust attenuation law in the rest-frame NUV region of star-forming galaxies within the redshift window 1.5 < z < 3. We focus on the NUV bump strength (B) and the total-to-selective extinction ratio (R-V), targeting a sample of 1753 galaxies. By comparing the data with a set of population synthesis models coupled to a parametric dust attenuation law, we constrain R-V and B, as well as the colour excess, E(B - V). We find a correlation between R-V and B, which can be interpreted either as a result of the grain size distribution, or a variation of the dust geometry among galaxies. According to the former, small dust grains are associated with a stronger NUV bump. The latter would lead to a range of clumpiness in the distribution of dust within the interstellar medium of star-forming galaxies. The observed wide range of NUV bump strengths can lead to a systematic in the interpretation of the UV slope beta typically used to characterize the dust content. In this study, we quantify these variations, concluding that the effects are Delta beta similar to 0.4.
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. Artículo firmado por 14 autores. We would like to thank Sandro Bressan for his comments and suggestions. MT acknowledges support from the Mexican 'Consejo Nacional de Ciencia y Tecnología' (CONACyT), with scholarship #329741, as well as the Royal Astronomical Society for travel funding related to this project. EMQ acknowledges the support of the European Research Council via the award of a Consolidator Grant (PI McLure). PGP wishes to acknowledge support from Spanish Government MINECO Grants AYA2015-63650-P and AYA201570815-ERC. This work has made use of the Rainbow Cosmological Surveys Database, which is operated by the Universidad Complutense de Madrid (UCM), partnered with the University of California Observatories at Santa Cruz (UCO/Lick, UCSC). Based on observations made with the GTC, installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma.