The AstroSat UV Deep Field North: The IRX-$\beta$ relation for the UV-selected galaxies at $z\sim$ 0.5-0.7

TL;DR

This study investigates the IRX-$eta$ relation in UV-selected galaxies at z~0.5-0.7, revealing a preference for SMC-like dust attenuation and a correlation between dust content and stellar mass, using multi-wavelength data and SED modeling.

Contribution

It provides new insights into the dust attenuation law in intermediate-redshift galaxies, favoring SMC-like extinction and highlighting the diversity in IRX-$eta$ relations.

Findings

Steeper SMC-like attenuation law fits the IRX-$eta$ data.

Strong positive correlation between IRX and stellar mass.

Large scatter in IRX-$eta$ relation indicates diverse dust properties.

Abstract

The relation between the observed UV continuum slope ($\beta$) 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 redshift 0.5 and 0.7 from the AstroSat UV Deep Field north (AUDFn) 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$\mu$m and 160$\mu$m bands. We further utilize the multi-band photometric data in 14 - 18 filters from the UVIT, KPNO, HST, Spitzer, and Herschel telescopes to perform spectral energy distribution (SED) modeling. Both the observed and model-derived IRX - $\beta$ 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 ($\delta$) in the IRX - $\beta$ plane: where the steeper SMC-like attenuation law prefers lower $\delta$ values. Our SED model based IRX - $\beta$ relation shows a preference for steeper SMC-like attenuation which we further confirm from the agreement between extinction-corrected star formation rates derived using H$\alpha$ emission line and the observed FUV plus reprocessed far-IR fluxes. The current study reveals a strong positive correlation between IRX and the galaxy stellar mass between $10^{9.5}$ and $10^{11.0}$ M$_{\odot}$, signifying increased dust production in more massive star-forming galaxies.