Galaxy groups in the Local universe (Makarov+, 2010) ================================================================================ Galaxy groups and clouds in the Local (z~0.01) universe Makarov D.I, Karachentsev I.D. ================================================================================ ADC_Keywords: Galaxy catalogs Keywords: galaxies: catalogues Description: We present an all-sky catalogue of 395 nearby galaxy groups revealed in the Local Supercluster and its surroundings. The groups and their associations are identified among 10914 galaxies at |b|>15deg with radial velocities V_LG<3500 km/s. Our group finding algorithm requires the group members to be located inside their zero-velocity surface. Hereby, we assume that individual galaxy masses are proportional to their total $K$-band luminosities, M/L_K = 6 Msun/Lsun. The sample of our groups, where each group has $n\geq 4$ members, is characterized by the following medians: harmonic radius R_h=204 kpc, radial velocity dispersion \sigma_V=74 km/s, K-band luminosity L_K=1.2x10^11 Lsun, virial and projected masses Mvir=2.4x10^12 and Mp=3.3x10^12 Msun/Lsun, respectively. Accounting for measurement error reduces the median masses by 30 per cent. For 98 per cent of identified groups the crossing time does not exceed the cosmic time, 13.7 Gyr, having the median at 2.2 Gyr. We examine different properties of the groups, in particular, of the known nearby groups and clusters in Virgo and Fornax. About a quarter of our groups can be classified as fossil groups where the dominant galaxy is at least ten times brighter than the other group members. In total, our algorithm identifies 54 per cent of galaxies to be members of groups. Together with triple systems and pairs they gather 82 per cent of the $K$-band light in Local universe. We have obtained the local value of matter density to be \Omega_m=0.08+-0.02 within a distance of ~40 Mpc assuming H0=73 km/s/Mpc. It is significantly smaller than the cosmic value, 0.28, in the standard \LambdaCDM model. The discrepancy between the global and local quantities of \Omega_m may be caused by the existence of Dark Matter component unrelated to the virial masses of galaxy systems. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file galaxies.dat 131 10766 List of members of groups and associations in the Local Supercluster groups.dat 229 1085 Groups catalogue in the Local Supercluster -------------------------------------------------------------------------------- Byte-by-byte Description of file: galaxies.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 2- 31 A30 --- name Galaxy name 36- 37 I2 h RAh Right ascension (J2000.0) 38- 39 I2 min RAm Right ascension (J2000.0) 40- 43 F4.1 s RAs Right ascension (J2000.0) 44 A1 --- DE- Declination sign (J2000.0) 45- 46 I2 deg DEd Declination (J2000.0) 47- 48 I2 arcmin DEm Declination (J2000.0) 49- 50 I2 arcsec DEs Declination (J2000.0) 54- 57 I4 km/s VLG Radial velocity respect to the Local Group 61- 62 I2 --- T ?Morphological type of the galaxy 66- 70 F5.2 Mag Kmag ?Corrected K-band total magnitude 74- 97 A24 --- group ?Group identificator 101-130 A30 --- assoc ?Association identificator -------------------------------------------------------------------------------- Byte-by-byte Description of file: groups.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 2- 25 A24 --- group Group identificator 30- 31 I2 h RAh Right ascension (J2000.0) 32- 33 I2 min RAm Right ascension (J2000.0) 34- 37 F4.1 s RAs Right ascension (J2000.0) 38 A1 --- DE- Declination sign (J2000.0) 39- 40 I2 deg DEd Declination (J2000.0) 41- 42 I2 arcmin DEm Declination (J2000.0) 43- 44 I2 arcsec DEs Declination (J2000.0) 48- 50 I3 --- N Population of the group 54- 57 I4 km/s VLG Radial velocity respect to the Local Group 61- 64 I4 km/s Sigma Standard deviation of velocity in the group 68- 70 I3 kpc Rh Projected harmonic radius of the group 74- 78 F5.2 --- lgL lg of total K-band luminosity of the group 83- 87 F5.2 --- lgMp lg of projected mass 91- 96 F6.1 --- ML mass-to-K-light ratio 102-106 F5.2 --- lgMpc ?lg of corrected projected mass 110-114 F6.1 --- MLc ?corrected mass-to-K-light ratio 119-122 F4.2 --- lgII lg of Isolation Index 126-132 I7 --- PGC1 ?PGC-number of brightest galaxy in the group 136-159 A24 --- gal1 name of brightest galaxy 163-164 I2 --- T1 ?Morphological type of the brightest galaxy 168-172 F5.2 Mag Kmag1 ?Corrected K-magnitude of the brightest galaxy 176-182 I7 --- PGC2 ?PGC-number of second bright galaxy in the group 186-215 A30 --- gal2 name of second bright galaxy 219-220 I2 --- T2 ?Morphological type of second bright galaxy 224-228 F5.2 Mag Kmag2 ?Corrected K-magnitude of second bright galaxy -------------------------------------------------------------------------------- ================================================================================ (End) 06-Aug-2010