The Physics of the Cold and Warm Interstellar Medium Through Radio Recombination Lines
Abstract
The interplay between star formation and the interstellar medium (ISM) gives rise to a feedback cycle that is one of the key drivers of galaxy evolution. The coldest gas in the ISM provides the fuel for star formation, and, in turn, the ISM is affected by feedback in the form of photons, shocks, and cosmic rays. Radio recombination lines (RRLs) offer a unique way of characterizing the gas in the ISM as extinction free probes of the gas kinematics, density, temperature, and radiation field. Hydrogen RRLs (HRRLs) probe gas where hydrogen is ionized, while carbon RRLs (CRRLs) probe cold gas in the HI-to-H2 transition layers. The superb sensitivity, spatial resolution, large field of view, and frequency resolution and coverage of the Square Kilometre Array (SKA) will allow for efficient observations of RRLs, that will make significant impacts to the study of the diffuse ISM. By observing RRLs with the SKA we will be able to determine the thermal and turbulent balance, chemical enrichment, sizes, and ionization rate of the cold and ionized gases from degree-scales down to arcsecond scales in our Galaxy.
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BibTeX
@misc{salas2026physics,
title = {{The Physics of the Cold and Warm Interstellar Medium Through Radio Recombination Lines}},
author = {Pedro Salas and Kimberly L. Emig and Matteo Luisi and Antoine Gusdorf and Lucie Cros and Loren D. Anderson and Alexander Tielens},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.32834},
eprint = {2610.32834},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.32834},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - The Physics of the Cold and Warm Interstellar Medium Through Radio Recombination Lines
AU - Pedro Salas
AU - Kimberly L. Emig
AU - Matteo Luisi
AU - Antoine Gusdorf
AU - Lucie Cros
AU - Loren D. Anderson
AU - Alexander Tielens
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.32834
UR - https://arxiv.org/abs/2610.32834
AB - The interplay between star formation and the interstellar medium (ISM) gives rise to a feedback cycle that is one of the key drivers of galaxy evolution. The coldest gas in the ISM provides the fuel for star formation, and, in turn, the ISM is affected by feedback in the form of photons, shocks, and cosmic rays. Radio recombination lines (RRLs) offer a unique way of characterizing the gas in the ISM as extinction free probes of the gas kinematics, density, temperature, and radiation field. Hydrogen RRLs (HRRLs) probe gas where hydrogen is ionized, while carbon RRLs (CRRLs) probe cold gas in the HI-to-H_2 transition layers. The superb sensitivity, spatial resolution, large field of view, and frequency resolution and coverage of the Square Kilometre Array (SKA) will allow for efficient observations of RRLs, that will make significant impacts to the study of the diffuse ISM. By observing RRLs with the SKA we will be able to determine the thermal and turbulent balance, chemical enrichment, sizes, and ionization rate of the cold and ionized gases from degree-scales down to arcsecond scales in our Galaxy.
ER -