Vla Imaging of Virgo Spirals in Atomic Gas (Viva). I. The Atlas and the H I Properties

Abstract

We present the results of a new VLA H i Imaging survey of Virgo galaxies, the VLA Imaging survey of Virgo galaxies in Atomic gas (VIVA). The survey includes high-resolution H i data of 53 carefully selected late type galaxies (48 spirals and five irregular systems). The goal is to study environmental effects on H i gas properties of cluster galaxies to understand which physical mechanisms affect galaxy evolution in different density regions, and to establish how far out the impact of the cluster reaches. As a dynamically young cluster, Virgo contains examples of galaxies experiencing a variety of environmental effects. Its nearness allows us to study each galaxy in great detail. We have selected Virgo galaxies with a range of star formation properties in low to high density regions (at projected distances from M87, d 87 = 0.3-3.3 Mpc). Contrary to previous studies, more than half of the galaxies in the sample (∼60%) are fainter than 12 mag in B T . Overall, the selected galaxies represent the late type Virgo galaxies (S0/a to Sd/Irr) down to m p 14.6 fairly well in morphological type, systemic velocity, subcluster membership, H i mass, and deficiency. The H i observations were done in C short (CS) configuration of the VLA radio telescope, with a typical spatial resolution of 15 and a column density sensitivity of ≈ 3-5 × 10 19 cm −2 in 3σ per 10 km s −1 channel. The survey was supplemented with data of comparable quality from the NRAO archive, taken in CS or C configuration. In this paper, we present H i channel maps, total intensity maps, velocity fields, velocity dispersions, global/radial profiles, position-velocity diagrams and overlays of H i/1.4 GHz continuum maps on the optical images. We also present H i properties such as total flux (S H i ), H i mass (M H i ), linewidths (W 20 and W 50 ), velocity (V H i ), deficiency (def H i ), and size (D eff H i and D iso H i ), and describe the H i morphology and kinematics of individual galaxies in detail. The survey has revealed details of H i features that were never seen before. In this paper, we briefly discuss differences in typical H i morphology for galaxies in regions of different galaxy densities. We confirm that galaxies near the cluster core (d 87 0.5 Mpc) have H i disks that are smaller compared to their stellar disks (D H i /D 25 < 0.5). Most of these galaxies in the core also show gas displaced from the disk, which is either currently being stripped or falling back after a stripping event. At intermediate distances (d 87 ∼ 1 Mpc) from the center, we find a remarkable number of galaxies with long one-sided H i tails pointing away from M87. In a previous letter, we argue that these galaxies are recent arrivals, falling into the Virgo core for the first time. In the outskirts, we find many gas-rich galaxies, with gas disks extending far beyond their optical disks. Interestingly, we also find some galaxies with H i disks that are smaller compared to their stellar disks at large clustercentric distances.

The influence of the cluster environment on the star formation efficiency of 12 Virgo spiral galaxies

“…B.13): has a strongly truncated gas disk with a one-sided arm structure to the west (Vollmer et al 2004a;Chung et al 2009). This arm structure consists of resettling ISM which has been pushed to larger galactic radii by a ram pressure stripping event ∼300 Myr ago (Vollmer et al 2004a;Boselli et al 2006).…”

“…The VLA Imaging of Virgo in Atomic gas (VIVA; Chung et al 2009) provide the Hi observations, while the mid-infrared (MIR) to farinfrared (FIR) imaging are obtained from the Spitzer Survey of Virgo (SPITSOV; Kenney et al 2009;Wong et al, in prep.). The observations from SPITSOV are more sensitive by a factor of √ 2 than the SINGS observations as SPITSOV is largely interested in detecting extraplanar and outer galaxy IR emission (Wong et al, in prep.).…”

Gas loss in simulated galaxies as they fall into clusters

“…Long tails of HI and ionized gas are observed in galaxies in several nearby clusters, consistent with the description given here (e.g., refs. 21,22,[25][26][27].…”

Molecular Gas Properties Under Icm Pressure in the Cluster Environment

“…Therefore it is unlikely that we are missing much CO 1 arcmin HI (green) 12CO (2-1) (white contours) FUV (blue) Hα (red) Optical (black) ICM wind direction (black arrows) Figure 2. The 12CO is more extended in the same direction as the H i gas (in the west; right side) (VIVA, Chung et al 2009), while its old stellar disk (DSS2 blue) is not disturbed. Both 12CO gas and H i gas are compressed in the south.…”

“…As shown by H i imaging data (e.g. Chung et al 2009), a number of H i-deficient galaxies are not only severely truncated within the stellar disk but are also disturbed (e.g. NGC 4522; Kenney et al 2004).…”