Are Brightest Halo Galaxies Central Galaxies

By R. Skibba, F. V. D. Bosch, Xiaohu Yang, S. More, H. Mo, F. Fontanot. 2010

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It is generally assumed that the central galaxy in a dark matter halo, that is the galaxy with the lowest specific potential energy, is also the brightest halo galaxy (BHG), and that it resides at rest at the centre of the dark matter potential well. This central galaxy paradigm (CGP) is an essential assumption made in various fields of astronomical research. In this paper, we test the validity of the CGP using a large galaxy group catalogue constructed from the Sloan Digital Sky Survey. For each group, we compute two statistics, and , which quantify the offsets of the line-of-sight velocities and projected positions of brightest group galaxies relative to the other group members. By comparing the cumulative distributions of and to those obtained from detailed mock group catalogues, we rule out the null hypothesis that the CGP is correct. Rather, the data indicate that in a non-zero fraction f(BNC)(M) of all haloes of mass M the BHG is not the central galaxy, but instead a satellite galaxy. In particular, we find that f(BNC) increases from similar to 0.25 in low-mass haloes (1012 h-1

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7903a7393c8eeb66df1bbbd2485e7611589b840e

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Citations in the corpus

Satellite kinematics – III. Halo masses of central galaxies in SDSS (2010, unknown): “As discussed in the text, we do not believe that our results are significantly affected by the fact that not all central galaxies are the brightest (or most massive) galaxies in their dark matter haloes, as shown by Skibba et al. (2010).”
Constraining the galaxy–halo connection over the last 13.3 Gyr: star formation histories, galaxy mergers and structural properties (2017, methodology): “In the case of satellite kinematics it has been noted that this method tends to give higher halo masses than other methods (like those described above, see e.g., More et al. 2011; Skibba et al. 2011; Rodŕıguez-Puebla et al. 2011).”
Cosmological Constraints from a Combination of Galaxy Clustering and Lensing -- III. Application to SDSS Data (2012, background): “It is worth mentioning that results based on groups might be potentially affected by the offset of central galaxies (see e.g. Skibba et al. 2011).”
Measures of Galaxy Environment I - What is "Environment"? (2011, methodology): “We have also assumed that central galaxies are always the brightest galaxy in a halo and lie at the centre of their potential well, although in a non-zero fraction of haloes, especially massive haloes, this assumption is not valid (Skibba et al. 2011).”
THE CONNECTION BETWEEN GALAXIES AND DARK MATTER STRUCTURES IN THE LOCAL UNIVERSE (2012, background): “Second, the assumption that galaxy with the most stellar mass is the central is not always true (e.g. Skibba et al. 2011) and can bias results based on the central galaxies.”
Galaxy evolution in groups and clusters: satellite star formation histories and quenching time-scales in a hierarchical Universe (2012, background): “2 http://www.mpa-garching.mpg.de/SDSS/DR7/ c© 2012 RAS, MNRAS 000, 1–25 is not always the one closest to the minimum of a halo’s potential well, particularly at high halo mass (Skibba et al. 2011).”
The dark side of galaxy colour (2013, background): “In reality, the halo may continue to form stars from 3 See their Figure 18 for a demonstration of this point. c© 0000 RAS, MNRAS 000, 000–000 its existing gas supply after this epoch, leading to a delay between zform and the actual quenching of star formation.”
Galaxy evolution in groups and clusters: star formation rates, red sequence fractions and the persistent bimodality (2011, methodology): “Using the Yang et al. (2007) group catalogue, Skibba et al. (2011) found evidence that up to 40 per cent of massive (>1014 M ) haloes have galaxies closest to halo centre that are not the brightest, with a decreasing fraction at lower halo mass.”
The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at z ∼ 1.4 (2015, background): “Such a model neglects the substantial relative velocity found for the brightest halo galaxies by Skibba et al. (2011) (see also Hikage et al. 2012 for the off-centerig effect of central galaxies), although emission line galaxies reside in less massive halos so that such an effect is expected to be…”
Weighing the Giants - I. Weak-lensing masses for 51 massive galaxy clusters: project overview, data analysis methods and cluster images (2012, background): “In many clusters, the BCG is indeed located near the bottom of the gravitational well of the cluster (e.g. Allen 1998; Smith et al. 2005; von der Linden et al. 2007; Best et al. 2007), but this is not always the case (Lin & Mohr 2004; Skibba et al. 2011).”
Towards a realistic population of simulated galaxy groups and clusters (2013, background): “Indeed, recent observational studies (e.g. Skibba et al. 2011; Balogh et al. 2011) have shown that there can sometimes be relatively large offsets between the BCG and these other choices of centre .”
Stellar Mass—Halo Mass Relation and Star Formation Efficiency in High-Mass Halos (2014, background): “They could thus be most naturally identified as analogs of central galaxies in smaller mass halos (although note that not all of the BCGs are closest to the center, e.g., Skibba et al. 2011).”
Intrinsic alignments of SDSS-III BOSS LOWZ sample galaxies (2014, background): “The assumption that the brightest galaxy truly resides at the center of the halo fails for about c© 0000 RAS, MNRAS 000, 000–000 25%-40% of the groups within our mass range (Skibba et al. 2011; Hikage et al. 2013), in which case the brightest galaxy is in fact a satellite galaxy.”