Virgo Cluster Region Research Articles

A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)

The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band (NB) Hα+[NII] imaging survey carried out with MegaCam at the Canada–France–Hawaii Telescope. The survey covers the whole Virgo cluster region from its core to one virial radius (104 deg2). The sensitivity of the survey is of f(Hα) ~ 4 × 10−17 erg s−1 cm−2 (5σ detection limit) for point sources and Σ(Hα) ~ 2 × 10−18 erg s−1 cm−2 arcsec−2 (1σ detection limit at 3 arcsec resolution) for extended sources, making VESTIGE the deepest and largest blind NB survey of a nearby cluster. This paper presents the survey in all its technical aspects, including the survey design, the observing strategy, the achieved sensitivity in both the NB Hα+[NII] and in the broad-band r filter used for the stellar continuum subtraction, the data reduction, calibration, and products, as well as its status after the first observing semester. We briefly describe the Hα properties of galaxies located in a 4 × 1 deg2 strip in the core of the cluster north of M87, where several extended tails of ionised gas are detected. This paper also lists the main scientific motivations for VESTIGE, which include the study of the effects of the environment on galaxy evolution, the fate of the stripped gas in cluster objects, the star formation process in nearby galaxies of different type and stellar mass, the determination of the Hα luminosity function and of the Hα scaling relations down to ~106 M⊙ stellar mass objects, and the reconstruction of the dynamical structure of the Virgo cluster. This unique set of data will also be used to study the HII luminosity function in hundreds of galaxies, the diffuse Hα+[NII] emission of the Milky Way at high Galactic latitude, and the properties of emission line galaxies at high redshift.

THE EXTENDED VIRGO CLUSTER CATALOG

We present a new catalog of galaxies in the wider region of the Virgo cluster, based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The Extended Virgo Cluster Catalog (EVCC) covers an area of 725 deg^2 or 60.1 Mpc^2. It is 5.2 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches out to 3.5 times the virial radius of the Virgo cluster. We selected 1324 spectroscopically targeted galaxies with radial velocities less than 3000 kms^-1. In addition, 265 galaxies that have been missed in the SDSS spectroscopic survey but have available redshifts in the NASA Extragalactic Database are also included. Our selection process secured a total of 1589 galaxies of which 676 galaxies are not included in the VCC. The certain and possible cluster members are defined by means of redshift comparison with a cluster infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification based on the visual inspection of optical images and a characterization of galaxies from their spectroscopic features. SDSS u, g, r, i, and z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC galaxies with the VCC in terms of morphology, spatial distribution, and luminosity function. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths.

H I DISTRIBUTION AND TULLY-FISHER DISTANCES OF GAS-POOR SPIRAL GALAXIES IN THE VIRGO CLUSTER REGION

We present aperture synthesis observations in the 21 cm line of pointings centered on the Virgo Cluster region spirals NGC 4307, NGC 4356, NGC 4411B, and NGC 4492 using the Very Large Array (VLA) radiotelescope in its CS configuration. These galaxies were identified in a previous study of the three-dimensional distribution of HI emission in the Virgo region as objects with a substantial dearth of atomic gas and Tully-Fisher (TF) distance estimates that located them well outside the main body of the cluster. We have detected two other galaxies located in two of our fields and observed bands, the spiral NGC 4411A and the dwarf spiral VCC 740. We provide detailed information of the gas morphology and kinematics for all these galaxies. Our new data confirm the strong HI-deficiency of all the main targets but NGC 4411B, which is found to have a fairly normal neutral gas content. The VLA observations have also been used to discuss the applicability of TF techniques to the five largest spirals we have observed. We conclude that none of them is actually suitable for a TF distance evaluation, whether due to the radical trimming of their neutral hydrogen disks (NGC 4307, NGC 4356, and NGC 4492) or to their nearly face-on orientation (NGC 4411A and B).

Optically Unseen H i Detections toward the Virgo Cluster Detected in the Arecibo Legacy Fast ALFA Survey

We report the discovery by the Arecibo Legacy Fast ALFA (ALFALFA) survey of eight H I features not coincident with stellar counterparts in the Virgo Cluster region. All of the H I clouds have cz < 3000 km s-1 and, if at the Virgo distance, H I masses between 1.9 × 107 and 1.1 × 109 M☉. Four of the eight objects were reported or hinted at by previous studies and "rediscovered" by ALFALFA. While some clouds appear to be associated with optical galaxies in their vicinity, others show no clear association with a stellar counterpart. Two of them are embedded in relatively dense regions of the cluster and are associated with M49 and M86; they were previously known. The others are mostly located in peripheral regions of the cluster. Especially notable are a concentration of objects toward the so-called M cloud, 3°-5° to the northwest of M87, and a complex of several clouds projected roughly halfway between M87 and M49. The object referred to as VIRGOHI 21 and proposed to be a "dark galaxy" is also detected and shown to be a tidal feature associated with NGC 4254.

Chiral Property of Spiral and Barred Spiral Galaxies in the Local Supercluster

We present an analysis of the chiral property of 667 spiral and barred spiral galaxies in the Local Supercluster (radial velocity <3 000 km s−1). The arms of a galaxy (spiral or barred spiral) can be distinguished according to their orientation (leading or trailing) relative to the direction of the rotation. We use environment of each galaxy as a subsample in order to study the chiral property of galaxies. In addition, equatorial position angle distributions of leading and trailing arm galaxies are studied. We classify our database according as their morphology, diameters, radial velocities, axial ratios and magnitudes. The distribution of trailing and leading arm galaxies in the Local Supercluster is found homogeneous. A significant dominance of either trailing or leading structures is noticed within the Virgo cluster region, suggesting that the aggregation of these structures might have already started there. The rotation axes of the galaxies in the Virgo cluster is found to lie in the equatorial plane. Chirality of galaxies is found strong for the subsamples that showed a random alignment in the equatorial position angle distribution. Possible explanations of the results will be presented.

Results From VLA Observations of Five Spiral Galaxies In The Virgo Cluster Region

AbstractNew HI synthesis observations have been made for the five spiral galaxies NGC 4307, NGC 4356, NGC 4411a/b and NGC 4492, located in the Virgo Cluster Region, with the Very Large Array in its CS configuration. All these objects, but NGC 4411a, belong to a sample of spirals identified in previous single-dish studies of the HI distribution within the Virgo Cluster and its outskirts. The thirteen members of that sample were selected for showing neutral gas deficiencies as strong as those of the inner galaxies of Virgo and other rich clusters, but apparently lying on the infall region.The goal of the present observations is to progress further on the identification of the external mechanisms that may be responsible for the reduction of the interstellar gas in spiral galaxies and thus contribute to the study of the evolution of galaxies in high-density environments. In particular, the results of this work are relevant for the ongoing debate on the pre-processing of galaxies prior to entering the cluster environment.

Tracing the warm-hot intergalactic medium in the local Universe

We present a simple method for tracing the spatial distribution and predicting the physical properties of the Warm-Hot Intergalactic Medium (WHIM), from the map of galaxy light in the Local Universe. Under the assumption that biasing is local and monotonic we map the ∼2 h -1 Mpc smoothed density field of galaxy light into the mass-density field, from which we infer the spatial distribution of the WHIM in the Local Supercluster. Taking into account the scatter in the WHIM density-temperature and density-metallicity relation, extracted from the z = 0 outputs of high-resolution and large-box-size hydrodynamical cosmological simulations, we are able to quantify the probability of detecting WHIM signatures in the form of absorption features in the X-ray spectra, along arbitrary directions in the sky. To illustrate the usefulness of this semi-analytical method we focus on the WHIM properties in the Virgo cluster region.

Radio continuum spectra of galaxies in the Virgo cluster region

New radio continuum observations of galaxies in the Virgo cluster region at 4.85, 8.6, and 10.55 GHz are presented. These observations are combined with existing measurements at 1.4 and 0.325 GHz. The sample includes 81 galaxies where spectra with more than two frequencies could be derived. Galaxies that show a radio-FIR excess exhibit central activity (HII, LINER, AGN). The four Virgo galaxies with the highest absolute radio excess are found within 2 ◦ of the center of the cluster. Galaxies showing flat radio spectra also host active centers. There is no clear trend between the spectral index and the galaxy's distance to the cluster center.

H I view of the Virgo cluster outskirts: implications on galaxy evolution

The H I deficiency pattern of the spiral population in the Virgo cluster region reveals a significant number of galaxies at very large clustercentric distances with gaseous deficiencies comparable to those measured in the cluster centers. We have used the output of cosmological -body simulations to investigate whether the gas-deficient galaxies on the outskirts of the Virgo cluster may have previously passed through its core. We find that the maximum radius reached by infalling galaxies as they bounce out of a Virgo-like cluster must be less than 2.5 virial radii, which results in a predicted velocity-distance diagram noticeably different from the one drawn by the data. The latter is fairly well reproduced, however, after including in the simulations distance errors at the 20% relative rms level. Yet, for several objects apparently over 5 Mpc in front or behind the Virgo center the assumption that they are instead close enough to the cluster to have passed already through its core strains the bounds of plausibility. Hence, unless these outlying H I-deficient Virgo's spirals have grossly incorrect distances, they cannot have lost their gas by interactions with the intracluster medium. This suggests that the evolution of spirals might begin already on the suburbs of clusters.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The Three-dimensional Structure of the Virgo Cluster Region from Tully-Fisher and H [CSC]i[/CSC] Data

The distances and H I contents of 161 spiral galaxies in the region of the Virgo cluster are used to gain insight into the complicated structure of this galaxy system. Special attention has been paid to the investigation of the suggestion presented in an earlier work that some peripheral Virgo groups may contain strongly gas-deficient spiral galaxies. The three-dimensional galaxy distribution has been inferred from quality distance estimates obtained by averaging distance moduli based on the Tully-Fisher relationship taken from eight published data sets previously homogenized, resulting in a relation with a dispersion of 0.41 mag. Previous findings that the spiral distribution is substantially more elongated along the line of sight than in the plane of the sky are confirmed by the current data. In addition, an important east-west disparity in this effect has been detected. The overall width-to-depth ratio of the Virgo cluster region is about 1 : 4, with the most distant objects concentrated in the western half. The filamentary structure of the spiral population and its orientation are also reflected by the H I–deficient objects alone. The H I deficiency pattern shows a central enhancement extending from ~16 to 22 Mpc in line-of-sight distance; most of this enhancement arises from galaxies that belong to the Virgo cluster proper. However, significant gas deficiencies are also detected outside the main body of the cluster in a probable group of galaxies at line-of-sight distances ~25–30 Mpc, lying in the region dominated by the southern edge of the M49 subcluster and clouds W' and W, as well as in various foreground galaxies. In the Virgo region, the H I content of the galaxies then is not a straightforward indicator of cluster membership.

Kinematic Disturbances in Optical Rotation Curves among 89 Virgo Disk Galaxies

For 89 galaxies, mostly spirals, in the Virgo cluster region, we have obtained optical long-slit major axis spectra of the ionized gas. We find: (1) One-half of the Virgo galaxies we observed have regular rotation patterns, while the other 50% exhibit kinematic disturbances ranging from mild to major. Velocity complexities are generally consistent with those resulting from tidal encounters or accretion events. Since kinematic disturbances are expected to fade within ~10^9 years, many Virgo galaxies have experienced several significant kinematic disturbances during their lifetimes. (2) A few Virgo galaxies have ionized gas of limited extent, with velocities exceptionally low for their luminosities. In these galaxies the gas must be not rotationally supported. (3) There is a remarkable difference in the distribution of galaxy systemic velocity for galaxies with Regular rotation curves and galaxies with Disturbed rotation curves. Galaxies with regular rotation patterns show a flat distribution with systemic velocity, while galaxies with disturbed kinematics have a Gaussian distribution very similar to that for the elliptical galaxies in Virgo. This suggests that spirals with disturbed kinematics are preferentially on radial orbits, which bring them to the cluster core, where tidal interactions are strong and/or more common. These interactions may alter the morphology of the galaxy, and may also play a role in driving the Virgo cluster toward dynamical equilibrium.

Surface photometry of spiral galaxies in the Virgo cluster region

view Abstract Citations (11) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Surface Photometry of Spiral Galaxies in the Virgo Cluster Region Yasuda, Naoki ; Okamura, Sandanori ; Fukugita, Masataka Abstract Photographic surface photometry is carried out for 246 spiral galaxies in the Virgo cluster region north of declination +5^deg^. The sample contains all spiral galaxies of "certain" and "possible" Virgo members in the Virgo Cluster Catalogue of Binggeli, Sandage, & Tammann. The sample also includes those galaxies which were used in the Tully-Fisher analyses of the Virgo cluster given in the literature. A catalog is presented for positions, B-band total magnitudes and inclinations for these galaxies, and they are compared with the data given in previous studies. Publication: The Astrophysical Journal Supplement Series Pub Date: February 1995 DOI: 10.1086/192123 Bibcode: 1995ApJS...96..359Y Keywords: Astronomical Photometry; Spiral Galaxies; Surface Properties; Virgo Galactic Cluster; Astronomical Catalogs; Astronomical Photography; Astronomy; GALAXIES: CLUSTERS: INDIVIDUAL NAME: VIRGO; GALAXIES: PHOTOMETRY full text sources ADS | data products SIMBAD (248) NED (246)

The UV Content of Virgo Cluster Galaxies

I present a preliminary analysis of three UV images of the Virgo cluster region, obtained by the FAUST experiment (Bowyer et al. 1993) in April 1992. FAUST is a wide-field imaging telescope covering an 8° area with effective resolution of 3′.5. The experiment was constructed by the Berkeley Space Astronomy Group together with the Laboratoire d'Astrophysique Spatiale of the CNES. It operated on board the Shuttle during the mission ATLAS-1.

Prospects for 1019eV cosmic ray studies in South Australia

We discuss some of the important elements necessary for the successful operation of a very large cosmic ray array. Some of these points are illustrated using a detector Monte Carlo. The importance of composition measurement is stressed, particularly in regard to anisotropy interpretation. We review some of the issues connected with the other uncertainty in anisotropy studies, the galactic magnetic field, and show that with reasonable assumptions about its large scale structure, an experimental site in the southern hemisphere would have a good view of both the Virgo cluster region and the Magellanic Clouds. The features of a possible site at Woomera in South Australia are discussed. Finally, some technical aspects of solar power and communication technology are reviewed. Some options for the array control, data collection procedures and system timing are outlined.

Virial mass and kinematics of the Virgo cluster

From line of sight velocities of galaxies in the Virgo cluster region given by Binggeli, Sandage and Tammann, 352 member galaxies in central 6°core of the cluster are determined by the maximum likelihood principle. Based on these member galaxies it is obtained that for the cluster the virial mass μ ν = 2.7×10 14 μ ⊙, total luminosity L B = 2.0×10 12 L ⊙, mass-luminosity ratio μ ν L B = 136 , and luminosity mass μ L = 4.1×10 13 μ ⊙. The velocity dispersion profile of the Virgo cluster is quite similar to that of the Coma, and a tendency of the observed velocity dispersion decreasing towards the cluster center is found. There is a strong morphological segregation in both space and velocity for the cluster members, early-type galaxies being more concentrated towards the cluster center and showing a smaller velocity dispersion than late types ( σ = 615 versus 827 km/ s). It is indicated from discussions on the virial mass and the mass segregation that the period of dynamic evolution when the Virgo cluster has been undergone is relatively quite short, almost no effect of mass segregation is shown, and it should be a young irregular cluster of galaxies.

Vacuum ultraviolet imagery of the Virgo cluster region. III - Diffuse far-ultraviolet radiation at high Galactic latitudes

Far-ultraviolet radiation over a wide sky region of −110° 60° was observed by a rocket-borne two-dimensional imager in the wavelength around 150 nm. The background far-ultraviolet radiation from the Virgo cluster region was also observed in the pointing phase of the same rocket experiment. Contributions from several components, such as airglows, faint stars, or molecular hydrogen emission, to the observed radiation were examined, and the diffuse far-ultraviolet background radiation at high Galactic latitudes was derived.

The radial velocity membership of the Virgo Cluster

Applying the principle of maximum likelihood to the radial velocity data of 572 galaxies in the Virgo Cluster region, we found 434 to be members of the cluster. The mean heliocentric velocity is 1247 ±37 km/s, and the dispersion is 752 ±27 km/s. Analysis shows that although Virgo Cluster has subcluster structures, we can still use the normal distribution as a reasonable first approxiaation to the distribution for the cluster members. The galaxies of different types seem to have different spatial distributions, the late type galaxies may still be in the stage of infall.

Vacuum ultraviolet imagery of the Virgo Cluster region. II - Total far-ultraviolet flux of galaxies

view Abstract Citations (19) References (78) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Vacuum Ultraviolet Imagery of the Virgo Cluster Region. II. Total Far-Ultraviolet Flux of Galaxies Kodaira, K. ; Watanabe, T. ; Onaka, T. ; Tanaka, W. Abstract The total flux in the far-ultraviolet region around 150 nm was measured for more than 40 galaxies in the central region of the Virgo Cluster, using two imaging telescopes on board a sounding rocket. The observed far-ultraviolet flux shows positive correlations with the H I 21 cm flux and the far-infrared flux for spiral galaxies, and with the X-ray flux and the radio continuum flux for elliptical galaxies. The former correlations of spiral galaxies are interpreted in terms of star formation activity, which indicates substantial depletion in the Virgo galaxies in accordance with the H I stripping. The latter correlations of elliptical galaxies indicate possible far-ultraviolet sources of young population, in addition to evolved hot stars. Far- ultraviolet fluxes from two dwarf elliptical galaxies were obtained tentatively, indicating star formation activity in elliptical galaxies. A high-resolution UV imagery by HST would be effective to distinguish the young population and the old population in elliptical galaxies. Publication: The Astrophysical Journal Pub Date: November 1990 DOI: 10.1086/169355 Bibcode: 1990ApJ...363..422K Keywords: Astronomical Photometry; Far Ultraviolet Radiation; Virgo Galactic Cluster; Color-Color Diagram; Elliptical Galaxies; Hot Stars; Spiral Galaxies; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: PHOTOMETRY; ULTRAVIOLET: GENERAL full text sources ADS | data products SIMBAD (100) NED (89) MAST (1) Related Materials (2) Part 1: 1989ApJ...342..238O Part 3: 1991ApJ...379..532O

Vacuum Ultraviolet Background Radiation Around the Virgo Cluster Region

The vacuum ultraviolet (λeff = 156 nm and δλ ≅ 30 nm) observation around the Virgo Cluster region (l = 280°–320° and b = 60°–80°) was performed by the GUV experiment, a rocket-borne two-dimensional imager. The diffuse background radiation in the high galactic latitude region was obtained after subtraction of the contributions from airglow, stars, and galaxies in the field of view. A comparison with HI 21 cm radio observations indicates a weak correlation of the diffuse ultraviolet (UV) background radiation with HI column density, suggesting a low scattering efficiency of the interstellar dust grains in the far-UV and the existence of the isotropic component in the diffuse background radiation.

FURTHER IMPROVED FORMULAE FOR THE TRANSFORMATION OF CATALOGUE OF GALAXIES AND CLUSTERS OF GALAXIES MAGNITUDES INTO THE BTS SYSTEM

ABSTRACT New formulae are presented to transform the CGCG magnitudes to the BS^T_ system developed by de Vaucouleurs and his collaborators. Formulae are provided for both the case where data from the Second Reference Catalogue are used and where data from the Uppsala General Catalogue are used. The regression formulae depend strongly on the mean surface brightness of the galaxy and less strongly on total brightness. The coefficients of these variables are different for galaxies in Volume 1 of the CGCG compared to galaxies in Volumes 2-6. The constant term in the regression formula depends on the morphological tape, the CGCG volume, and whether the galaxy is in the Virgo cluster region for Volumes 1 and 2. The calculation of the weights of the observations has been improved so that the distribution of the normalized residuals is close to a Gaussian distribution.