A deeper look at the dust attenuation law of star-forming galaxies at high redshift

Tress, M., Ferreras, I., Pérez González, P. G., Bressan, A., Barro, G., Domínguez Sánchez, H., Eliche Moral, C. 2019. A deeper look at the dust attenuation law of star-forming galaxies at high redshift. Monthly Notices of the Royal Astronomical Society 488, 2, 2301-2311 DOI: 10.1093/mnras/stz1851

A diverse range of dust attenuation laws is found in star-forming galaxies. In particular, Tress et al. (2018) studied the SHARDS survey to constrain the NUV bump strength (B) and the total-to-selective ratio (R-V) of 1753 star-forming galaxies in the GOODS-N field at 1.5 < z < 3. We revisit here this sample to assess the implications and possible causes of the correlation found between R-V and B. The UVJ bicolour plot and main sequence of star formation are scrutinized to look for clues into the observed trend. The standard boundary between quiescent and star-forming galaxies is preserved when taking into account the wide range of attenuation parameters. However, an additional degeneracy – regarding the effective attenuation law – is added to the standard loci of star-forming galaxies in the UVJ diagram. A simple phenomenological model with an age-dependent extinction (at fixed dust composition) is compatible with the observed trend between R-V and B, whereby the opacity decreases with the age of the populations, resulting in a weaker NUV bump when the overall attenuation is shallower (greyer). In addition, we compare the constraints obtained by the SHARDS sample with dust models from the literature, supporting a scenario where geometry could potentially drive the correlation between R-V and B.

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