This work considers the Virgo cluster of galaxies, focusing on its structure, kinematics, and morphological landscape. Our principal aim is to estimate the virial mass of the cluster. For this purpose, we present a sample of 1537 galaxies with radial velocities V_LG_<2600km/s situated within a region of 30x20 degrees around M87. About half of the galaxies have distance estimates. We selected 398 galaxies with distances in the (17+/-5)Mpc range. Based on their 1D and 2D number-density profiles and their radial velocity dispersions, we made an estimate for the virial mass of the Virgo cluster. Results. We identify the infall of galaxies towards the Virgo cluster core along the Virgo Southern Extention filament. From a 1D profile of the cluster, we obtain the virial mass estimate of (6.3+/-0.9)x10^14^ solar masses, which is in tight agreement with its mass estimate via the external infall pattern of galaxies. We conclude that the Virgo cluster outskirts between the virial radius and the zero-velocity radius do not contain significant amounts of dark matter beyond the virial radius.
A deep optical galaxy search in the southern Milky Way - aimed at reducing the width of the Zone of Avoidance - revealed 3279 galaxy candidates on the IIIaJ film copies of the ESO/SRC survey above the diameter limit of D greater than approximately 0.2 arcmin. Only 112 (3.4%) were previously catalogued. The surveyed region (266<l<296 and -10<b<+8) lies in the extension of the Hydra and Antlia clusters. Optical properties of the unveiled galaxies such as positions, diameters, magnitudes, morphological types are given in Table 1. Cross-identifications with the IRAS PSC (Cat. <II/125>) are given in Table 2.
In this second paper of the catalogue series of galaxies behind the southern Milky Way, we report on the deep optical galaxy search in the Crux region (289{deg}<~l<~318{deg} and -10{deg}<~b<~10{deg}) and the Great Attractor region (316{deg}<~l<~338{deg} and -10{deg}<~b<~10{deg}). The galaxy catalogues are presented, a brief description of the galaxy search given, as well as a discussion on the distribution and characteristics of the uncovered galaxies. A total of 8183 galaxies with major diameters D>~0.2 arcmin were identified in this ~850 square degree area: 3759 galaxies in the Crux region and 4423 galaxies in the Great Attractor region. Of the 8183 galaxies, 229 (2.8%) were catalogued before in the optical (3 in radio) and 251 galaxies have a reliable (159), or likely (92) cross-identification in the IRAS Point Source Catalogue (3.1%). A number of prominent overdensities and filaments of galaxies are identified. They are not correlated with the Galactic foreground extinction and hence indicative of extragalactic large-scale structures. Redshifts obtained at the South African Astronomical Observatory (SAAO) for 518 of the newly catalogued galaxies in the Crux and Great Attractor regions (Fairall et al., 1998, Cat. <J/A+AS/127/463>; Woudt et al., 1999, Cat. <J/A+A/352/39>) confirm distinct voids and clusters in the area here surveyed. With this optical galaxy search, we have reduced the width of the optical `Zone of Avoidance' for galaxies with extinction-corrected diameters larger than 1.3' from extinction levels A_B>~1.0mag to A_B>~3.0mag: the remaining optical Zone of Avoidance is now limited by |b|<~3{deg} (see Fig. 16).
V- and I- band CCD photometry of the central 0.18 square degree of Abell 168 was observed in November and December 1993 at the 1.05m Kiso Schmidt telescope (f/3.1). The CCD chip has 1000x1018 pixels, the pixel size is 0.752arcsec, giving a field of view of 12.0x12.7 arcmin. The total observed region was covered by 7 individual CCD fields. Note that some revisions were made by the author (TOMITA Akihiko) compared to the original publication.
Results of optical, radio, and submillimeter studies of the nearby galaxy cluster A1185 are presented. Coordinates have been obtained for 115 galaxies that are either cluster members or field galaxies in the direction of A1185. Radio spectra for a number of galaxies in this cluster have been derived using observations on the RATAN-600 radio telescope at 2.7,3.9,7.6, and 31 cm, together with data published in other study. At the cluster center some of the galaxies have either flat or inverted spectra.
We present photometry and spectroscopy for seven deep fields containing distant clusters of galaxies with 0.35<z<0.55. Positions and photometric parameters, including r-magnitudes g-r and r-i colors, surface brightnesses, and photometric profile types are given for about 2000 galaxies. Low-resolution spectroscopy is obtained from which redshifts are determined for 289 objects, of which 190 are cluster members.
This catalog represents the combination of results published in two papers: Ferguson, H.C. 1989 A.J. 98, 367 (Paper II) and Ferguson, H.C. and Sandage, A. 1990 A.J. 100, 1 (Paper III). See the Historical Notes section below. Please note that the data from Paper II were previously archived as catalog VII/160. This catalog supersedes that earlier dataset. The following paragraphs describe the data included from the two papers. (Paper II) This paper presents a catalog of 2678 galaxies within an area of nearly 40 deg^2^ centered on the Fornax Cluster at {alpha}=3h35m and {delta}=-35.7deg. The data have been obtained from visual inspection of 26 deep large-scale (10.9arcsec/mm) plates taken with the du Pont 2.5m reflector at the Las Campanas Observatory, and from digital photometry of an ESO/SRC blue survey plate covering roughly the same area of the sky. The catalog is essentially diameter limited, with a limiting diameter of 17arcsec at an isophoto of B_T_ =26.5. Within this survey region, the catalog includes 340 likely cluster members and 2338 likely background galaxies. For cluster members, this listing should be complete to B_T_=18 (corresponding to M_BT_=13.0, assuming a distance modulus of m-M=31.9) and contains likely members down to B_T_=20. Cluster membership is for the most part based on galaxy morphology. By virtue of their low surface brightness, dwarf galaxies in the cluster can be distinguished with a high degree of certainty from background galaxies. Radial velocities are included for 89 galaxies in the survey, providing a reliable indicator of membership in these cases. As additional support for our rejection of background galaxies, we model the spatial distribution of various types of galaxies as the sum of a King model cluster component superimposed on a uniform background. Using maximum-likelyhood fits to these spatial distributions, we find a core radius of 0.7deg. for a King model fit to the cluster, and show that there are few, if any, cluster members contained in the sample of background galaxiesBD (Paper III) Five nearby groups of galaxies have been surveyed using large-scale plates from the 2.5 m duPont Telescope at Las Campanas Observatory. Catalogs of galaxies brighter than B_T_ ~ 20 are presented for the Leo, Dorado, NGC 1400, NGC 5044, and Antlia groups. A total of 1044 galaxies are included, from visual inspection of 14 plates, covering 31deg square. Galaxies have been classified in the extended Hubble system, and group memberships have been assigned based on velocity (where available) and morphology. About half the galaxies listed are likely members of one of the nearby groups. The catalogs are complete to B_T_ ~ 18, although the completeness limits vary slightly from group to group. Based on King model fits to the surface density profiles, the core radii of the groups range from 0.3 to 1 Mpc, and central densities range from 120 to 1900 galaxies Mpc^-3^ brighter than M_BT_ = -12.5. Dynamical analysis indicates that all of the groups of likely to be gravitationally bound.
We have previously identified an excess population of predominantly red galaxies around a sample of 31 radio-loud quasars (RLQs) at 1<z<2. Here we show that these fields have a surface density of extremely red objects (EROs, with R-K>6) 2.7 times higher than the general field. Assuming these EROs are passively evolved galaxies at the quasar redshifts, they have characteristic luminosities of only ~L*. Only one of four RLQ fields has an excess of J-K-selected EROs with J-K>2.5; thus, those objects are mostly unrelated to the quasars. We also present new multiwavelength data and analyses on the fields of four of these quasars at z_q_~1.54, obtained to build more detailed pictures of the environments of these quasars and the galaxies within them.
Cosmic Dawn II (CoDa II) is a new, fully-coupled radiation-hydrodynamics simulation of cosmic reionization and galaxy formation and their mutual impact, to redshift z<6. With 4096^3^ particles and cells in a 94Mpc box, it is large enough to model global reionization and its feedback on galaxy formation while resolving all haloes above 10^8^M_{sun}_. Using the same hybrid CPU-GPU code RAMSES-CUDATON as CoDa I in Ocvirk et al. (2016MNRAS.463.1462O), CoDa II modified and re-calibrated the subgrid star-formation algorithm, making reionization end earlier, at z>~6, thereby better matching the observations of intergalactic Lyman-alpha opacity from quasar spectra and electron-scattering optical depth from cosmic microwave background fluctuations. CoDa II predicts a UV continuum luminosity function in good agreement with observations of high-z galaxies, especially at z=6. As in CoDa I, reionization feedback suppresses star formation in haloes below ~2x10^9^M_{sun}_, though suppression here is less severe, a possible consequence of modifying the star-formation algorithm. Suppression is environment-dependent, occurring earlier (later) in overdense (underdense) regions, in response to their local reionization times. Using a constrained realization of {LAMBDA}CDM constructed from galaxy survey data to reproduce the large-scale structure and major objects of the present-day Local Universe, CoDa II serves to model both global and local reionization. In CoDa II, the Milky Way and M31 appear as individual islands of reionization, i.e. they were not reionized by the progenitor of the Virgo cluster, nor by nearby groups, nor by each other. Description: The galaxy catalogs for redshifts z=10 down to z=6 (the simulation ended at z=5.8) are provided. Galaxies are identified as Friends-of-Friends dark matter haloes with a linking length ll=0.2. Stars are associated to each halo if they are within a sphere of radius r200. Magnitudes are computed using a BPASS stellar population model, as detailed in the article. No dust opacity is considered.
We discuss the X-ray and optical properties of the massive galaxy cluster MACSJ1206.2-0847 (z=0.4385), discovered in the Massive Cluster Survey (MACS). Our Chandra observation of the system yields a total X-ray luminosity of 2.4x10^45^erg/s (0.1-2.4keV) and a global gas temperature of 11.6+/-0.7keV, very high values typical of MACS clusters. In both optical and X-ray images, MACSJ1206.2-0847 appears close to relaxed in projection, with a pronounced X-ray peak at the location of the brightest cluster galaxy (BCG); we interpret this feature as the remnant of a cold core. A spectacular giant gravitational arc, 15-arcsec in length, bright (V~21) and unusually red (R-K=4.3), is seen 20-arcsec west of the BCG; we measure a redshift of z=1.036 for the lensed galaxy. From our Hubble Space Telescope image of the cluster, we identify the giant arc and its counter image as a sevenfold imaged system. An excess of X-ray emission in the direction of the arc coincides with a mild galaxy overdensity and could be the remnant of a minor merger with a group of galaxies. We derive estimates of the total cluster mass as well as of the mass of the cluster core using X-ray, dynamical and gravitational-lensing techniques. For the mass enclosed by the giant arc (r<119kpc), our strong-lensing analysis based on Hubble Space Telescope imaging yields a very high value of 1.1x10^14^M_{sun}_, inconsistent with the much lower X-ray estimate of 0.5x10^14^M_{sun}_. Similarly, the virial estimate of 4x10^15^M_{sun}_ for the total cluster mass, derived from multi-object spectroscopy with Canada-France-Hawaii Telescope (CFHT) and the VLT of 38 cluster members, is significantly higher than the corresponding X-ray estimate of 1.7x10^15^M_{sun}_. We take the discrepancy between X-ray and other mass estimates to be indicative of pronounced substructure along the line of sight during an ongoing merger event, an interpretation that is supported by the system's very high velocity dispersion of 1580km/s.
