We measure the molecular-to-atomic gas ratio, R mol, and the star formation rate (SFR) per unit molecular gas mass, SFEmol, in 38 nearby galaxies selected from the Virgo Environment Traced in CO (VERTICO) survey. We stack ALMA 12CO (J = 2−1) spectra coherently using H i velocities from the VIVA survey to detect faint CO emission out to galactocentric radii r gal ∼ 1.2 r 25. We determine the scale lengths for the molecular and stellar components, finding a ∼3:5 relation compared to ∼1:1 in field galaxies, indicating that the CO emission is more centrally concentrated than the stars. We compute R mol as a function of different physical quantities. While the spatially resolved R mol on average decreases with increasing radius, we find that the mean molecular-to-atomic gas ratio within the stellar effective radius R e , R mol(r < R e ), shows a systematic increase with the level of H i, truncation and/or asymmetry (HI perturbation). Analysis of the molecular- and the atomic-to-stellar mass ratios within R e , R ⋆ mol ( r < R e ) and R ⋆ atom ( r < R e ) , shows that VERTICO galaxies have increasingly lower R ⋆ atom ( r < R e ) for larger levels of HI perturbation (compared to field galaxies matched in stellar mass), but no significant change in R ⋆ m o l ( r < R e ) . We also measure a clear systematic decrease of the SFEmol within R e , SFEmol(r < Re ), with increasingly perturbed H i. Therefore, compared to field galaxies from the field, VERTICO galaxies are more compact in CO emission in relation to their stellar distribution, but increasingly perturbed atomic gas increases their R mol and decreases the efficiency with which their molecular gas forms stars.
|Publication status||Published - 2022 Dec 1|
Bibliographical noteFunding Information:
V.V. acknowledges support from the scholarship ANID-FULBRIGHT BIO 2016-56160020 and funding from NRAO Student Observing Support (SOS)—SOSPA7-014. A.D.B., S.V., and V.V. acknowledge partial support from the NSF grants AST2108140 and AST1615960. T.B. acknowledges support from the National Research Council of Canada via the Plaskett Fellowship of the Dominion Astrophysical Observatory. A.R.H.S. gratefully acknowledges funding through the Jim Buckee Fellowship at ICRAR-UWA. T.A.D. acknowledges support from the UK Science and Technology Facilities Council through grants ST/S00033X/1 and ST/W000830/1. B.L. acknowledges support from the Korea Astronomy and Space Science Institute grant funded by the Korea government (MSIT; project No. 2022-1-840-05). L.C.P. acknowledges support from the Natural Sciences and Engineering Research Council of Canada. A.C. acknowledges support from the NRF (grant Nos. 2022R1A2C100298211 and 2022R1A6A1A03053472) by the Korean government. L.C. acknowledges support from the Australian Research Council Discovery Project and Future Fellowship funding schemes (DP210100337, FT180100066).
ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. In addition, publications from NA authors must include the standard NRAO acknowledgment: The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Part of this work was conducted on the unceded territory of the Lekwungen and Coast Salish peoples. We acknowledge and respect the Songhees, Esquimalt, WSÁNEĆ and T’Sou-ke Nations whose historical relationships with the land continue to this day. Support for CARMA construction was derived from the Gordon and Betty Moore Foundation; the Kenneth T. and Eileen L. Norris Foundation; the James S. McDonnell Foundation; the Associates of the California Institute of Technology; the University of Chicago; the states of California, Illinois, and Maryland; and the NSF. CARMA development and operations were supported by the NSF under a cooperative agreement and by the CARMA partner universities. This research is based on observations collected at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie (MPA) and the Instituto de Astrofisica de Andalucia (CSIC).
© 2022. The Author(s). Published by the American Astronomical Society.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science