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arXiv · 2509.01990

The radial variation of the silicate-to-carbon ratio in M31 probed by PRIMA

Jérémy Chastenet·Ilse De Looze·Maarten Baes·Simone Bianchi·Viviana Casasola·Laure Ciesla·Stephen Eales·Jacopo Fritz·Frédéric Galliano·Suzanne C. Madden·Angelos Nersesian·Monica Relaño·Matthew W. L. Smith·Stefan van der Giessen·Emmanuel Xilouris
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Abstract

The properties of interstellar dust grains are being scrutinized more than ever before, with the advent of large facilities. Infrared emission from dust grains is a powerful asset than can help constrain their physical and chemical properties. Among these, the relative ratio of carbon-rich to silicate-rich grains remains one that has not yet been investigated thoroughly, due to the lack of dedicated instruments and modeling limitations. In this paper, we quantify the modeling degeneracies inherent to constraining the far-infrared (far-IR) slope of the dust emission spectral energy distribution. Used as a proxy for the silicate-to-carbon ratio, we find that recovering the far-IR slope is affected by the estimate of the local radiation field, and the input abundances of different grain species. We show that PRIMA's Hyperspectral Imaging will lead to better constrained local radiation fields which will aid -- together with PRIMA's polarization capabilities -- to better constrain the silicate-to-carbon ratio in M31, and how it spatially varies within the galaxy.

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Jérémy Chastenet, Ilse De Looze, Maarten Baes, Simone Bianchi, Viviana Casasola, Laure Ciesla, Stephen Eales, Jacopo Fritz, Frédéric Galliano, Suzanne C. Madden, Angelos Nersesian, Monica Relaño, Matthew W. L. Smith, Stefan van der Giessen, Emmanuel Xilouris. 2025-09-02. The radial variation of the silicate-to-carbon ratio in M31 probed by PRIMA. https://doi.org/10.1117/1.jatis.11.3.031623

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