The GALEX Ultraviolet Virgo Cluster Survey (GUViCS)

Abstract

We study the role of the environment on galaxy evolution using a sample of 868 galaxies in the Virgo cluster and in its surrounding regions that are selected from the GALEX Ultraviolet Virgo Cluster Survey (GUViCS) with the purpose of understanding the origin of the red sequence in dense environments. The sample spans a wide range in morphological types (from dwarf ellipticals to Im and BCD) and stellar masses (10 7 M star 10 11.5 M ). We collected multifrequency data covering the whole electromagnetic spectrum for most of the galaxies, including UV, optical, mid-and far-infrared imaging data, as well as optical and HI spectroscopic data. We first identify the different dynamical substructures that compose the Virgo cluster, and we calculate the local density of galaxies using different methods. We then study the distribution of galaxies belonging to the red sequence, the green valley, and the blue cloud within the different cluster substructures or as a function of galaxy density. Our analysis indicates that all the most massive galaxies (M star 10 11 M ) are slow rotators and are the dominant galaxies of the different cluster substructures, which are generally associated with a diffuse X-ray emission. They are probably the result of major merging events that occurred at early epochs, as also indicated by their very old stellar populations. Slow rotators of lower stellar mass (10 8.5M star 10 11 M ) are also preferentially located within the different high-density substructures of the cluster. Their position in the velocity space indicates that they are virialised within the cluster; thus, they are Virgo members since its formation. They have been shaped by gravitational perturbations occurring within the infalling groups that later form the cluster (pre-processing). On the contrary, low-mass star-forming systems are extremely rare in the inner regions of the Virgo cluster A, where the density of the intergalactic medium is at its maximum. Our ram pressure stripping models consistently indicate that these star-forming systems can be rapidly deprived of their interstellar medium during their interaction with the intergalactic medium. The lack of gas quenches their star-formation activity transforming them into quiescent dwarf ellipticals. This mild transformation does not perturb the kinematic properties of these galaxies, which still have rotation curves typical of star-forming systems.

Under pressure: quenching star formation in low-mass satellite galaxies via stripping

“…This picture is supported by observations of local clusters, which find very few star-forming satellites at stellar masses of 10 9.5 M versus the ∼ 30% quenched fraction measured for group and Milky Way-like hosts (e.g. Smith et al 2012;Boselli et al 2014b;Phillips et al 2015;Sánchez-Janssen et al 2016). …”

The GALEX Ultraviolet Virgo Cluster Survey (GUViCS)

“…In this region the sky coverage is 94% (Boselli et al 2014a) at the depth of the All Imaging Survey (AIS), where the completeness is 20 mag, and 65% at the depth of the Medium Imaging Survey (MIS; 21.5 mag) 1 . Unfortunately, because of a failure of the farultraviolet (FUV) detector, this survey was completed only in the NUV.…”

“…Boselli et al , 2008aBoselli et al ,b, 2014a). The UV data extracted from this survey have been recently published in Voyer et al (2014), and the study of the physical properties of Virgo cluster galaxies derived from a multifrequency analysis have been presented in Boselli et al (2014a). In two other companion papers we presented the study of the extraplanar star formation activity of a few gas stripped galaxies in the cluster (Boissier et al 2012) and of the diffuse Galactic emission of the UV scattered light in the Virgo direction (Boissier et al 2015).…”

H i observations of galaxies in the southern filament of the Virgo Cluster with the Square Kilometre Array Pathfinder KAT-7 and the Westerbork Synthesis Radio Telescope

“…Subclusters around the ellipticals M86 and M49 (whose systemic velocities are, respectively, −181 and 950 km s −1 , Kim et al 2014) are merging with the main cluster around the central elliptical M87. Several H I imaging surveys of the cluster revealed that the H I discs of its central late-type galaxies are truncated to well within the optical discs, suggesting that ICM-ISM interactions play an important role in driving the evolution of galaxies in the inner region of the cluster (Warmels 1988;Cayatte et al 1990;Chung et al 2009;Boselli et al 2014). Wide-area H I surveys like HIPASS (H I Parkes All-Sky Survey, Barnes et al 2001), ALFALFA (Arecibo Legacy Fast ALFA, Giovanelli et al 2005) and AGES (Arecibo Galaxy Environment Survey, Auld et al 2006) done with singledish telescopes have helped detect many low H I mass galaxies such as early-type and late-type dwarf galaxies, but also starless dark galaxies and several H I clouds (e.g.…”