Advancing extragalactic spectral line studies with the Square Kilometre Array Observatory
Jacco Th. van Loon, Viviana Casasola, Manuela Bischetti, Sandra Etoka, Hans-Rainer Klöckner, Mamta Pandey-Pommier, Mark Sargent, Nick Seymour, Andrea Tarchi
astro-ph.GA, astro-ph.CO, astro-ph.IM, astro-ph.SR
Submitted: 2026-07-03
Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/vanLoon01. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopes
License: http://creativecommons.org/licenses/by-nc-sa/4.0/
The gist: We present an overview of the Square Kilometre Array Observatory (SKAO) science potential in the area of extragalactic spectral lines besides 21-cm neutral hydrogen.
Terminology
Abstract
We present an overview of the Square Kilometre Array Observatory (SKAO) science potential in the area of extragalactic spectral lines besides 21-cm neutral hydrogen. It highlights the main points from the SKAO Science Book chapters on individual topics, but is augmented by additional prospects. The SKAO will push studies and use of masers, kilomasers, megamasers, molecular and radio-recombination-line emission and absorption to a wider variety of environments, including to very high redshift where it may detect the first molecule (HeH+). It will open the door to measurements of hydrogen and helium isotopes, probing the conditions for star formation and Big Bang nucleosynthesis. While the planned SKAO of the 2030s (AA*) is destined to forge major progress, an SKAO as initially envisaged (AA4) will truly transform the landscape, and an extension towards higher frequencies (up to 24 GHz) would enable water maser and ammonia surveys in nearby galaxies and systematic molecular gas inventories at redshift 5.
Sources
- The hyperfine transition of 3He+ as a probe of the intergalactic medium
- Anticipated Performance of the Square Kilometre Array -- Phase 1 (SKA1)
- Revealing deuterium Balmer lines in HII regions with VLT-UVES
- Spectrally and spatially resolved (sub)millimeter HCN-to-HCO$^{+}$ flux ratios in nearby ultraluminous infrared galaxies
- MeerKAT discovery of a high-redshift strongly-lensed hydroxyl gigamaser
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