VERTICO

VI. Cold-gas asymmetries in Virgo cluster galaxies

¹ Leiden Observatory, Leiden University, PO Box 9513 2300 RA Leiden, The Netherlands
e-mail: iroberts@strw.leidenuniv.nl
² Herzberg Astronomy and Astrophysics Research Centre, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC 8 V9E 2E7, Canada
³ Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
⁴ Department of Physics & Astronomy, McMaster University, 1280 Main Street W, Hamilton, ON L8S 4M1, Canada
⁵ Department of Astronomy, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
⁶ Department of Physics, Engineering Physics and Astronomy, Queen’s University, Kingston, ON K7L 3N6, Canada
⁷ Aix Marseille Univ, CNRS, CNES, LAM, Marseille 13013, France
⁸ International Centre for Radio Astronomy Research, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
⁹ ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australia
¹⁰ Department of Physics & Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
¹¹ Institute for Earth and Space Exploration, The University of Western Ontario, London, ON N6A 3K7, Canada
¹² Cardiff Hub for Astrophysics Research & Technology, School of Physics & Astronomy, Cardiff University, Queens Buildings, Cardiff CF24 3AA, UK
¹³ Department of Physics & Astronomy, University of Victoria, PO Box 1700 STN CSC Victoria, BC V8W 2Y2, Canada
¹⁴ Observatorio Astronómico Nacional (IGN), C/Alfonso XII, 3, 28014 Madrid, Spain
¹⁵ Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
¹⁶ Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Daejeon 34055, Republic of Korea
¹⁷ Departamento de Física, Universidad Técnica Federico Santa María, Vicuña Mackenna 3939, San Joaquín, Santiago de Chile, Chile
¹⁸ Royal Military College of Canada, PO Box 17000 Station Forces, Kingston, ON K7K 7B4, Canada
¹⁹ Department of Astronomy, University of Maryland, College Park, MD 20742, USA
²⁰ Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
²¹ Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney, NSW 2006, Australia

Received: 5 April 2023
Accepted: 22 May 2023

Abstract

We analyse cold-gas distributions in Virgo cluster galaxies using resolved observations of CO(2-1), which traces molecular hydrogen (H₂), and H I from the Virgo Environment Traced In CO (VERTICO) and VLA Imaging of Virgo in Atomic Gas (VIVA) surveys. From a theoretical perspective, it is expected that environmental processes in clusters will have a stronger influence on diffuse atomic gas compared to the relatively dense molecular gas component, and that these environmental perturbations can compress the cold interstellar medium in cluster galaxies, leading to elevated star formation. In this work we observationally test these predictions for star-forming satellite galaxies within the Virgo cluster. We divided our Virgo galaxy sample into H I-normal, H I-tailed, and H I-truncated classes and show, unsurprisingly, that the H I-tailed galaxies have the largest quantitative H I asymmetries. We also compared Virgo galaxies to a control sample of non-cluster galaxies and find that the former, on average, have H I asymmetries that are 40 ± 10% larger than the latter. There is less separation between control, H I-normal, H I-tailed, and H I-truncated galaxies in terms of H₂ asymmetries, and on average, Virgo galaxies have H₂ asymmetries that are only marginally (20 ± 10%) larger than the control sample. We find a weak correlation between H I and H₂ asymmetries over our entire sample, but a stronger correlation for the galaxies that are strongly impacted by environmental perturbations. Finally, we divided the discs of the H I-tailed Virgo galaxies into a leading half and trailing half according to the observed tail direction. We find evidence for excess molecular gas mass on the leading halves of the disc. This excess molecular gas is accompanied by an excess in the star formation rate such that the depletion time is, on average, unchanged.