How Galaxies Lose Their Gas

SH20_lostGas.pngToby Brown et al. present the Virgo Environment Traced in CO (VERTICO) survey, a new effort to map 12CO(2− 1), 13CO(2−1), and C18O(2−1) in 51 Virgo Cluster galaxies with the Atacama Compact Array, part of the Atacama Large Millimeter/submillimeter Array (ALMA). The primary motivation of VERTICO is to understand the physical mechanisms that perturb molecular gas disks, and therefore star formation and galaxy evolution, in dense environments. This first paper contains an overview of VERTICO’s design and sample selection, 12CO(2−1) observations, and data reduction procedures. The authors characterize global 12CO(2 − 1) fluxes and molecular gas masses for the 49 detected VERTICO galaxies, provide upper limits for the two non-detections, and produce resolved 12CO(2 − 1) data products (median resolution = 8 arcsec ≈ 640 pc). Azimuthally averaged 12CO(2 − 1) radial intensity profiles are presented along with derived molecular gas radii. The authors demonstrate the scientific power of VERTICO by comparing the molecular gas size–mass scaling relation for their galaxies with a control sample of field galaxies, highlighting the strong effect that radius definition has on this correlation. They discuss the drivers of the form and scatter in the size–mass relation and highlight areas for future work. VERTICO is an ideal resource for studying the fate of molecular gas in cluster galaxies and the physics of environment- driven processes that perturb the star formation cycle. Upon public release, the survey will provide a homogeneous legacy dataset for studying galaxy evolution in our closest cluster.

Image Caption: Upper: CO 2-1 emission from galaxies in the Virgo cluster, plus the optical image. Lower: Molecular gas in the merging galaxy system NGC 4567 and 4568.

Publication: Toby Brown ( Herzberg Astronomy and Astrophysics Research Centre, McMaster University) et al., VERTICO: The Virgo Environment Traced In CO Survey, 2021 Astrophysical Journal Supplement Series (accepted), arXiv:2111:00937.

NRAO Press Release: A Cosmic Whodunit: ALMA Study Confirms What’s Robbing Galaxies of Their Star-Forming Gas

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