http://arxiv.org/abs/2210.05381
We measure the molecular-to-atomic gas ratio, $R_{\rm mol}$, and the star formation rate (SFR) per unit molecular gas mass, SFE${\rm mol}$, in 38 nearby galaxies selected from the Virgo Environment Traced in CO (VERTICO) survey. We stack ALMA $^{12}$CO(J=2-1) spectra coherently using \hi\ velocities from the VIVA survey to detect faint CO emission out to galactocentric radii $r{\rm gal} \sim 1.2\,r_{25}$. We determine the scale-lengths for the molecular and stellar components, finding a $\sim$3:5 relation between them, and indicating that CO emission tends to be more centrally concentrated than stellar mass in VERTICO galaxies when compared to field galaxies. While the spatially-resolved $R_{\rm mol}$ shows a decreasing trend with radius similar to field samples, the mean molecular-to-atomic gas ratio within the stellar effective radius $R_{\rm e}$, $R_{\rm mol}(r<R_{\rm e})$, shows a systematic increase with the level of \hi\, truncation and/or asymmetry (perturbation). Analysis of the molecular- and the atomic-to-stellar mass ratios within $R_{\rm e}$, $R^{\rm mol}{\star}(r<R{\rm e})$ and $R^{\rm atom}{\star}(r<R{\rm e})$, respectively, shows that while VERTICO galaxies do not exhibit significant variations in $R^{\rm mol}{\star}(r<R{\rm e})$ with \hi\, perturbation and when compared to galaxies from the field, they do show low $R^{\rm atom}{\star}(r<R{\rm e})$ (i.e., perturbation is enough to lower their $R^{\rm atom}{\star}(r<R{\rm e})$). We measure a systematic decrease of the SFE${\rm mol}$ within $R{\rm e}$, SFE${\rm mol}(r<R{\rm e})$, with increasingly perturbed \hi. Compared to field galaxies, the increasingly perturbed atomic gas in VERTICO galaxies increases their $R_{\rm mol}$ and decreases the efficiency with which their molecular gas forms stars.
V. Villanueva, A. Bolatto, S. Vogel, et. al.
Wed, 12 Oct 22
62/75
Comments: N/A