TheHerschelVirgo Cluster Survey

Abstract

Aims. We investigate the dust-to-gas mass ratio and the environmental effects on the various components of the interstellar medium for a spatially resolved sample of Virgo spirals. Methods. We have used the IRAM-30 m telescope to map over their full extent NGC 4189, NGC 4298, NGC 4388, and NGC 4299 in the 12 CO(1-0) and the 12 CO(2-1) lines. We observed the same lines in selected regions of NGC 4351, NGC 4294, and NGC 4424. The CO observations are combined with Herschel maps in 5 bands between 100-500 μm from the HeViCS survey, and with HI data from the VIVA survey, to obtain spatially resolved dust and gas distributions. We studied the environmental dependencies by adding to our sample eight galaxies with 12 CO(1-0) maps from the literature. Results. We estimate the integrated mass of molecular hydrogen for the galaxies observed in the CO lines. We find molecular-to-total gas mass fractions between 0.04 ≤ f mol ≤ 0.65, with the lowest values for the dimmest galaxy in the B-band. The integrated dust-togas ratio ranges between 0.011 and 0.004. For the 12 mapped galaxies we derive the radial distributions of the atomic gas, molecular gas, and dust. We also study the effect of different CO-to-H 2 conversion factors. Both the molecular gas and the dust distributions show steeper radial profiles for HI-deficient galaxies and the average dust-to-gas ratio for these galaxies increases or stays radially constant. On scales of ∼3 kpc, we find a strong correlation between the molecular gas and the 250 μm surface brightness that is tighter than average for non-deficient galaxies. The correlation becomes linear if we consider the total gas surface mass density. However, the inclusion of atomic hydrogen does not improve the statistical significance of the correlation. Conclusions. The environment can modify the distributions of molecules and dust within a galaxy, although these components are more tightly bound than the atomic gas.

Galaxy And Mass Assembly (GAMA): Gas Fueling of Spiral Galaxies in the Local Universe. I. The Effect of the Group Environment on Star Formation in Spiral Galaxies

“…However, environment-driven shifts in the spatial distribution of gas and dust with respect to the stellar component, as observed, e.g., in galaxies in the Virgo Cluster (Cortese et al 2012a;Pappalardo et al 2012), as well as systematic differences in the dust content of galaxies of a given mass as a function of environment, can be envisaged and represent a major source of uncertainty in the attenuation corrections applied and by extension in our analysis.…”

“…This might account for the empirical result that the dust content of spiral galaxies in the Virgo Cluster shows a lack of strong variation as a function of cluster-centric radius Tuffs et al 2002). In addition, the observed radial gradients in the dust-to-gas ratio indicate that gas is much more efficiently removed than dust (Cortese et al 2012b;Pappalardo et al 2012), especially within the optical stellar disk. As the dust in the outer regions of the disk has a smaller effect on the observed NUV flux than that in the inner regions, this will mitigate the effect of stripping on the attenuation corrections.…”

“…If the dust content of galaxies is systematically different in the group and field environment, this will affect the attenuation corrections applied. However, with the stripping of material from galaxies by various mechanisms known to affect galaxies in groups, as seen in the Virgo Cluster (e.g., Chung et al 2009;Pappalardo et al 2012), it appears likely that any systematic difference will tend toward the ratio of gas to stars being smaller in groups. This would lead to overcorrections of the observed emission, making any observed suppression of star formation activity a lower limit on the actual suppression.…”

Cosmic Evolution of Dust in Galaxies: Methods and Preliminary Results

“…Furthermore, these observations have also revealed the spatially resolved dust properties in nearby galaxies and accordingly provided new constraints on dust evolution models in galaxies (e.g., Meixner et al 2010;Pappalardo et al 2012;P12). In spite of these significant progresses in observational studies, theoretical studies have not yet explained many of these latest new observational results.…”

Determining the Halo Mass Scale Where Galaxies Lose Their Gas*

“…Theoretical investigations have shown that this process can remove significant amounts of both diffuse and cold gas from within the optical radius of galaxies in rich cluster environments (Quilis et al 2000;Roediger & Brüggen 2007, 2008Tonnesen & Bryan 2009). Observational investigations have shown both dramatic stripping of the gas content of galaxies in cluster environments (Kenney & Koopmann 1999;Kenney et al 2004;Cortese et al 2011;Pappalardo et al 2012;Boselli et al 2014;Fumagalli et al 2014;Jáchym et al 2014;Jaffé et al 2015) and statistical evidence from rotation curve asymmetries in cluster galaxies with normal morphology that ram pressure stripping is likely important in those environments (Bösch et al 2013).…”