A multi-scale view of molecular gas and magnetic fields in the Antennae galaxies

@misc{lasrado2026multiscale,
  title = {{A multi-scale view of molecular gas and magnetic fields in the Antennae galaxies}},
  author = {Akhil Lasrado and Enrique Lopez-Rodriguez and Claudia Cicone and Axel Weiss and Andreas Lundgren and Boy Lankhaar and Robert Wissing and Sijing Shen},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.03346},
  eprint = {2610.03346},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.03346},
}

TY  - UNPB
TI  - A multi-scale view of molecular gas and magnetic fields in the Antennae galaxies
AU  - Akhil Lasrado
AU  - Enrique Lopez-Rodriguez
AU  - Claudia Cicone
AU  - Axel Weiss
AU  - Andreas Lundgren
AU  - Boy Lankhaar
AU  - Robert Wissing
AU  - Sijing Shen
PY  - 2026
DA  - 2026/10/02
PB  - arXiv
DO  - 10.48550/arxiv.2610.03346
UR  - https://arxiv.org/abs/2610.03346
AB  - Major mergers are transformative events in galaxy evolution, dynamically reshaping the stellar and gas makeup of the hosts, as well as the galaxy-scale magnetic fields (B-fields) that permeate their interstellar medium (ISM), altering both B-field strength and configuration. In this work, we study in detail the link between the co-evolving gas and B-fields in the cold ISM phase of the nearby Antennae galaxy merger (NGC 4038/4039), using CO(3-2) data from the LAsMA receiver at the APEX telescope and ALMA, together with archival 154 μm dust polarization data from the SOFIA/HAWC+. We characterize trends between measurements of molecular gas intensity and velocity dispersion with polarization measurements at kpc-scales with the APEX and SOFIA data. We find anti-correlations with CO intensity (ρ≲−0.6) and CO velocity dispersion (ρ≲−0.4), which are signposts of geometric depolarization. Since dust polarization measurements are a density-weighted line-of-sight integrated average of B-field vectors below the beam size, the ALMA data can serve as a proxy of density structures below the SOFIA beam on a channel-by-channel basis. Through a geometric analysis of structures in the ALMA channels, we identify salient kinematic features in the overlap region strongly aligned with the SOFIA-inferred B-field orientation. This indicates that these kinematic features might dominantly lend their orientation to the measured field direction, assuming a correspondence between molecular gas structures and galactic B-fields, owing to their density or high polarization fraction. We also identify a modest trend (ρ∼0.5) between the coherence of the molecular gas, a proxy of the line-of-sight angular dispersion, at small scales, and the SOFIA polarization fraction, showing that the polarization fraction measured at ∼2 kpc scales is sensitive to structures at ∼50 pc scales.
ER  -