Galaxy groups and clouds in the local (z∼ 0.01) Universe

By Dmitry I. Makarov, I. Karachentsev. 2010

153 citations recorded by the source corpus.

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 10 914 galaxies at |b| > 15° with radial velocities VLG < 3500 km s−1. 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/LK= 6 M⊙/L⊙. The sample of our groups, where each group has n≥ 4 members, is characterized by the following medians: mean projected radius 〈R〉= 268 kpc, radial velocity dispersion σV= 74 km s−1, K-band luminosity LK= 1.2 × 1011 L⊙, virial and projected masses Mvir= 2.4 × 1012 and Mp= 3.3 × 1012 M⊙, respectively. Accounting for measurement error reduces the median masses by 30 per cent. For 97 per cent of identified groups the crossing time does not exceed the cosmic time, 13.7 Gyr, with the median at 3.8 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 10 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 the local Universe. We have obtained the local value of matter density to be Ωm= 0.08 ± 0.02 within a distance of ∼40 Mpc assuming H0= 73 km s−1 Mpc−1. It is significantly smaller than the cosmic value, 0.28, in the standard ΛCDM model. The discrepancy between the global and local quantities of Ωm may be caused by the existence of a dark matter component unrelated to the virial masses of the galaxy systems.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/5509b0c47321f9d179948ba4d5f0071e7c40ab8e

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Citations in the corpus

COSMICFLOWS-2: THE DATA (2013, background): “Alternative group catalogs exist: locally (Makarov & Karachentsev 2011) and on large scales (Crook et al. 2007).”
Galaxy Groups Within 3500 km s−1 (2017, methodology): “In an FOF-based recipe, Makarov & Karachentsev (2011) do introduce a mass effect with an assumption about how Ks-band luminosity and mass are correlated.”
ELVIS: Exploring the Local Volume in Simulations (2013, background): “…avenue for characterizing the faint end of the global luminosity function and for studying resolved stellar populations as beacons from an earlier age (see, e.g. Makarov & Karachentsev 2011; Weisz et al. 2011; ? sgarriso@uci.edu McConnachie 2012; Karachentsev & Kaisina 2013; Tully et al. 2013).”
The stellar mass-halo mass relation of isolated field dwarfs : a critical test of ΛCDM at the edge of galaxy formation (2016, background): “Only one of these has reported X-ray emission (Romanowsky et al. 2009), but they do span a similar mass range to the Giodini et al. (2012) sample (Zhang et al. 2007; Makarov & Karachentsev 2011; Peñarrubia et al. 2016).”
Flux- and volume-limited groups/clusters for the SDSS galaxies: catalogues and mass estimation (2014, methodology): “…several other techniques for group and cluster extraction have been developed, well reviewed by Gal (2006) and recently applied by Yang et al. (2005), Koester et al. (2007), Yang et al. (2007), Hao et al. (2010), Makarov & Karachentsev (2011), Wen et al. (2012), and Muñoz-Cuartas & Müller (2012).”