MUSE ALMA Haloes Survey
The interactions between gas and galaxies are of paramount importance to our understanding of structure formation. A fundamental element of such baryon cycle studies is a complete census of the condensed matter (stars and cold gas) in both galaxies and their immediate surroundings, the so-called circumgalactic medium. Of particular importance are the processes of converting molecular gas into stars and deciphering whether this <100K gas is tracing gas flows. The MUSE-ALMA Haloes survey has assembled probes of the neutral atomic gas H I, ionised gas and stellar component for a sample of 79 z∼0.5 galaxies. This is achieved by combining absorption line spectroscopy of background quasars to probe the low density circumgalactic gas with emission line tracers of both ionised gas and stars. This webpage provides the release of the data characterising the molecular phase of some of the MUSE-ALMA Haloes targets so as to reach a complete census of their condensed baryons. ALMA’s unique millimetre coverage and high sensitivity is ideal to characterise the CO emission of these z∼0.5 H I-selected galaxies. By measuring the molecular mass, kinematics, gas flows and gas fractions, this project then: i) quantifies the role of molecular gas in H I-rich galaxies, ii) characterises the molecular phase of gas flows from morphokinematics analyses, and iii) establishes a census of the condensed baryons in the interstellar and circumgalactic media. Ultimately, these results will provide unique insights into the baryon cycle - a crucial component
Proposers:
PI: Celine Peroux (European Southern Observatory, Germany)
co-PIs: Varsha Kulkarni (University of South Carolina, US), Laurent Chemin (Universidad Andres Bello, Chile)
co-Is: Ramona Augustin (Potsdam, Germany), Andy Biggs (Astronomy Technology Centre, UK), Victoria Bollo (European Southern Observatory, Germany), Benedetta Casavecchia (MPA, Germany), Aleksandra Hamanowicz (Space Telescope Institute, Baltimore, US), Rob Ivison (European Southern Observatory, Germany), Arjun Karki (University of South Carolina, US), Simon Weng (European Southern Observatory, Germany), Martin Zwaan (European Southern Observatory, Germany)
Team members:
Tamsyn O'Beirne (European Southern Observatory, Germany & Swinburne, Australia)
Jianhang Chen, Capucine Barfety, Linda Tacconi, Natascha Forster-Schreiber (all MPE, Germany)
Contact person for questions: Celine Peroux
Main deliveries:
The data delivery folder can be found here and includes all the final products for each field, with the naming conventions following the ALMA observatory recommendations.
Publications:
A pilot study was provided in Peroux et al. 2019.
Example of multi-phase kinematics enable by MUSE ALMA Haloes data are presented in Szakacs et al. 2021.
The MUSE ALMA Haloes survey is described in Peroux et al. 2022.
The first MUSE-ALMA Haloes Large Programme paper reports CO detections in Bollo et al. 2026.
The MUSE-ALMA Haloes Large Programme data release paper is Peroux et al. 2026.
Detailed kinematic studies are provided in Barfety et al. 2026.
A census of the baryons in the primary targets is available from O Beirne et al. 2026.
This links to all MUSE ALMA Haloes papers.
Additional resources:
Here is the team website.