Characterizing the UV-to-NIR shape of the dust attenuation curve of IR luminous galaxies up to z$\sim$2

TL;DR

This study examines the UV-to-NIR dust attenuation curves of IR-luminous galaxies at z~2, revealing a grayer UV slope and NIR flattening, which impacts derived galaxy properties and emphasizes the need for flexible attenuation models.

Contribution

It introduces a flexible double power-law model for dust attenuation curves that aligns well with radiative transfer results and improves galaxy property estimations.

Findings

Attenuation curves are grayer in UV and flatter in NIR than classical models.

Larger NIR attenuation leads to higher stellar mass estimates.

Star formation rates depend more on total attenuation than curve shape.

Abstract

In this work we investigate the far-UV to NIR shape of the dust attenuation curve of a sample of IR selected dust obscured (U)LIRGs at z$\sim$2. The spectral energy distributions (SEDs) are fitted with CIGALE, a physically-motivated spectral synthesis model based on energy balance. Its flexibility allows us to test a wide range of different analytical prescriptions for the dust attenuation curve, including the well-known Calzetti and Charlot & Fall curves, and modified versions of them. The attenuation curves computed under the assumption of our reference double power-law model are in very good agreement with those derived, in previous works, with radiative transfer (RT) SED fitting. We investigate the position of our galaxies in the IRX-$\beta$ diagram and find this to be consistent with grayer slopes, on average, in the UV. We also find evidence for a flattening of the attenuation curve in the NIR with respect to more classical Calzetti-like recipes. This larger NIR attenuation yields larger derived stellar masses from SED fitting, by a median factor of $\sim$ 1.4 and up to a factor $\sim$10 for the most extreme cases. The star formation rate appears instead to be more dependent on the total amount of attenuation in the galaxy. Our analysis highlights the need for a flexible attenuation curve when reproducing the physical properties of a large variety of objects.