Sieging HELM's deep: PRIMA unveils the far-infrared properties of highly extincted low-mass galaxies

Abstract

Although the majority of star-forming galaxies show a tight correlation between stellar mass and dust extinction, recent James Webb Space Telescope observations have revealed a peculiar population of Highly Extincted Low-Mass (HELM) galaxies, which could revolutionise our understanding of dust production mechanisms. To fully understand the dust content of these galaxies, which are a minority of the overall galaxy population, far-infrared observations over large areas are pivotal. In this paper, we derive the expected PRIMAger, the far-IR (24-235$\hat{I}¼m$) imaging camera proposed for the Probe far-IR Mission for Astrophysics, fluxes for a set of photometric candidates HELM galaxies. Taking into account a deep survey of 1000h over $1\mathrm{de}{\mathrm{g}}^2$, we expect to detect around $3.1\times 10^4$ HELM sources in at least one PRIMAger filter, 100 of which are at z=1-1.5. For 32% of this sample, there will be observations in at least four PRIMAger filters, covering at least the 90 to $240\hat{I}¼m$ wavelength range, which will allow us to obtain a detailed fit of the dust emission and estimate the dust mass.

11 pages, 4 figures, accepted by JATIS. This paper is part of the JATIS special issue focused on the PRobe Infrared Mission for Astrophysics (PRIMA) probe mission concept. The issue is edited by Matt Griffin and Naseem Rangwala (JATIS VOL. 11 NO. 3 | July 2025)