ESA Voyage 2050 white paper: A complete census of the gas phases in and around galaxies, far-UV spectropolarimetry as a prime tool for understanding galaxy evolution and star formation

Abstract

Lebouteiller et al.: A complete census of the gas phases in and around galaxies Another interesting prospect is to transpose the same level of details that has been reached for the Milky Way to the ISM in external galaxies, in particular in metal-poor galaxies, where the ISM chemical composition, physical conditions, and topology (arrangement of various phases) change dramatically, with significant consequences on the star-formation properties and on the overall galaxy evolution. We need to know, in particular, how star formation proceeds in quasi-pristine or pristine environments and what is the role of accreting clouds and compact objects in regulating the star formation process. To circumvent systematic biases in column density determinations and to examine the ISM enrichment as a function of the environment, next far-UV missions should be versatile enough to observe stellar clusters and individual O/B stars at distances of few Mpc to few 100s Mpc respectively, with a spectral resolution power R ∼ 10 5 and 10 4 respectively. Such requirements are also necessary to perform statistical analyses of background quasar lines of sight intersecting the CGM of galaxies at various redshifts. The CGM is an important component of galaxies that connects the galaxy to the cosmic web and is, as such, at the center of many processes that we do not yet fully understand. With future UV missions, we ought to be able to fill the gap between the various physical scales and phases and to comprehend the role of gas exchanges and flows for galaxy evolution. We advocate a far-UV space telescope that will be able to tackle these issues. Such an observatory would enable access to the range ≈ 900 − 3100 Å, and would require an exceptionally large mirror > 5 m. The optimal observation mode would be spectropolarimetry with a resolution of R 10 5 .

Vibrationally Resolved Absorption and Fluorescence Cross Sections of Adamantane in the Far-ultraviolet Spectral Range on an Absolute Scale

“…With only a few spectral high-resolution UV satellite missions flying until 2023, however, several future UV satellite projects have already been scheduled (SPARC; Jewell et al 2018), are under construction (WSO-UV; Shustov et al 2021), and/or are scheduled to successfully leave their conceptional phase soon (POLLUX; Muslimov et al 2018). The idea of understanding the chemical evolution of the galaxy through a broad multispectral observation (Lebouteiller et al 2019) requires the knowledge of numerous molecular fingerprints, from simple to complex molecular species, for their unambiguous identification and interpretation.…”