The AstroSat UV Deep Field North: The IRX–β Relation for the UV-selected Galaxies at z ∼ 0.5−0.7

Abstract

The relation between the observed UV continuum slope ( β ) and the infrared excess (IRX) is used as a powerful probe to understand the nature of dust attenuation law in high-redshift galaxies. We present a study of 83 UV-selected galaxies between a redshift of 0.5 and 0.7 from the AstroSat UV Deep Field north that encloses the GOODS-North field. Using empirical relation, we estimate the observed IRX of 52 galaxies that are detected in either one or both of the Herschel PACS 100 and 160 μ m bands. We further utilize the multiband photometric data in 14–18 filters from the Ultra-Violet Imaging Telescope, KPNO, Hubble Space Telescope, Spitzer, and Herschel telescopes to perform spectral energy distribution (SED) modeling. Both the observed and model-derived IRX– β values show a large scatter within the span of previously known relations, signifying diversity in dust attenuation. We found a distinct relation between the best-fit power-law slope of the modified Calzetti relation ( δ ) in the IRX– β plane, where the steeper SMC-like attenuation law prefers lower δ values. Our SED model-based IRX– β relation shows a preference for steeper SMC-like attenuation, which we further confirm from the agreement between extinction-corrected star formation rates derived using the H α emission line and the observed far-ultraviolet plus reprocessed far-IR fluxes. The current study reveals a strong positive correlation between IRX and the galaxy's stellar mass between 10 ^9.5 and 10 ^11.0 M _⊙ , signifying increased dust production in more massive star-forming galaxies.

Keywords

• High-redshift galaxies
• Interstellar dust extinction
• Galaxy evolution
• Ultraviolet surveys