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arXiv · 2402.05182

Little evolution of dust emissivity in bright infrared galaxies from $2 < z < 6$

B. A. Ward·S. A. Eales·R. J. Ivison·V. Arumugam
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Abstract

Variations in the dust emissivity index, $\beta$, within and between galaxies, are evidence that the chemistry and physics of dust must vary on large scales, although the nature of the physical and/or chemical variations is still unknown. In this paper we estimate values of $\beta$ and dust temperature for a sample of 109 dusty star-forming galaxies (DSFGs) over the range, $2 < z < 6$. We compare the results obtained with both an optically-thin model and a general opacity model, finding that our estimates of $\beta$ are similar between the models but our estimates of dust temperature are not. We find no evidence of a change in $\beta$ with redshift, with a median value of $\beta = 1.96$ for the optically-thin model with a confidence interval (16 - 84%) of 1.67 to 2.35 for the population. Using simulations, we estimate the measurement errors from our procedure and show that the variation of $\beta$ in the population results from intrinsic variations in the properties of the dust in DSFGs. At a fixed far-infrared luminosity, we find no evidence for a change in dust temperature, $T_\textrm{dust}$, with redshift. After allowing for the effects of correlated measurement errors, we find an inverse correlation between $\beta$ and $T_\textrm{dust}$ in DSFGs, for which there is also evidence in low-redshift galaxies.

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B. A. Ward, S. A. Eales, R. J. Ivison, V. Arumugam. 2024-02-07. Little evolution of dust emissivity in bright infrared galaxies from $2 < z < 6$. https://arxiv.org/abs/2402.05182

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