Tamsyn O'Beirne | Searcharxiv

arXiv2026

MUSE-ALMA Haloes XIII. Molecular gas in $z \sim 0.5$ HI-selected galaxies

We present new results from the MUSE-ALMA Haloes survey, covering 79 galaxies associated with strong HI absorption at redshift about 0.5. Our ALMA Cycle 10 observations add 39 systems to the initial 21, bringing the total to 60 galaxies. CO emission is detected in 9 new galaxies, and in 12 of 60 total, doubling the number of CO-emitting HI-selected galaxies and probing 1.2 dex deeper in molecular gas mass than previous studies. These galaxies span a wide range of stellar masses and metallicities. By comparing CO(2-1) and CO(3-2) properties with star formation rates and gas-phase metallicities from VLT/MUSE and HST, we find a dual behaviour in star formation efficiency: low-mass systems follow main-sequence scaling relations, while high-mass systems show suppressed star formation. This diversity indicates that HI absorbers trace both evolved and younger galaxies, providing a key step toward completing the baryon census at redshift about 0.5.

astro-ph.GA↗

arXiv2023

The HI in Ring Galaxies Survey (HI-RINGS) -- Effects of the bar on the HI gas in ring galaxies

We present a new high-resolution neutral atomic hydrogen (HI) survey of ring galaxies using the Australia Telescope Compact Array (ATCA). We target a sample of 24 ring galaxies from the Buta (1995) Southern Ring Galaxy Survey Catalogue in order to study the origin of resonance-, collisional- and interaction-driven ring galaxies. In this work, we present an overview of the sample and study their global and resolved HI properties. In addition, we also probe their star formation properties by measuring their star formation rates (SFR) and their resolved SFR surface density profiles. We find that a majority of the barred galaxies in our sample are HI deficient, alluding to the effects of the bar in driving their HI deficiency. Furthermore, for the secularly evolving barred ring galaxies in our sample, we apply Lindblad's resonance theory to predict the location of the resonance rings and find very good agreement between predictions and observations. We identify rings of HI gas and/or star formation co-located at one or the other major resonances. Lastly, we measure the bar pattern speed ($Ω_{\textrm{bar}}$) for a sub-sample of our galaxies and find that the values range from 10 -- 90 km s$^{-1}$ kpc$^{-1}$, in good agreement with previous studies.

astro-ph.GA↗