TY - JOUR
T1 - Luminous red galaxies in clusters
T2 - Central occupation, spatial distributions and miscentring
AU - Hoshino, Hanako
AU - Leauthaud, Alexie
AU - Lackner, Claire
AU - Hikage, Chiaki
AU - Rozo, Eduardo
AU - Rykoff, Eli
AU - Mandelbaum, Rachel
AU - More, Surhud
AU - More, Anupreeta
AU - Saito, Shun
AU - Vulcani, Benedetta
N1 - Publisher Copyright:
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2015/4/28
Y1 - 2015/4/28
N2 - Luminous red galaxies (LRG) from the Sloan Digital Sky Survey are among the best understood samples of galaxies and are employed in a broad range of cosmological studies. In this paper, we study how LRGs occupy massive haloes via counts in clusters and reveal several unexpected trends. Using the red-sequence Matched-filter Probabilistic Percolation (redMaPPer) cluster catalogue, we derive the central occupation of LRGs as a function richness. We show that clusters contain a significantly lower fraction of central LRGs than predicted from the two-point correlation function. At halo masses of 1014.5M⊙, we find Ncen = 0.73 compared to Ncen = 0.89 from correlation studies. Our central occupation function for LRGs converges to 0.95 at large halo masses. A strong anticorrelation between central luminosity and cluster mass at fixed richness is required to reconcile our results with those based on clustering studies. We derive the probability that the brightest cluster member is not the central galaxy. We find PBNC ≈ 20-30 per cent which is a factor of ~2 lower than the value found by Skibba et al. Finally, we study the radial offsets of bright non-central LRGs from cluster centres and show that bright non-central LRGs follow a different radial distribution compared to red cluster members. This work demonstrates that even the most massive clusters do not always have an LRG at the centre, and that the brightest galaxy in a cluster is not always the central galaxy.
AB - Luminous red galaxies (LRG) from the Sloan Digital Sky Survey are among the best understood samples of galaxies and are employed in a broad range of cosmological studies. In this paper, we study how LRGs occupy massive haloes via counts in clusters and reveal several unexpected trends. Using the red-sequence Matched-filter Probabilistic Percolation (redMaPPer) cluster catalogue, we derive the central occupation of LRGs as a function richness. We show that clusters contain a significantly lower fraction of central LRGs than predicted from the two-point correlation function. At halo masses of 1014.5M⊙, we find Ncen = 0.73 compared to Ncen = 0.89 from correlation studies. Our central occupation function for LRGs converges to 0.95 at large halo masses. A strong anticorrelation between central luminosity and cluster mass at fixed richness is required to reconcile our results with those based on clustering studies. We derive the probability that the brightest cluster member is not the central galaxy. We find PBNC ≈ 20-30 per cent which is a factor of ~2 lower than the value found by Skibba et al. Finally, we study the radial offsets of bright non-central LRGs from cluster centres and show that bright non-central LRGs follow a different radial distribution compared to red cluster members. This work demonstrates that even the most massive clusters do not always have an LRG at the centre, and that the brightest galaxy in a cluster is not always the central galaxy.
KW - Galaxies: clusters: general
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U2 - 10.1093/mnras/stv1271
DO - 10.1093/mnras/stv1271
M3 - Article
AN - SCOPUS:84940032069
SN - 0035-8711
VL - 452
SP - 998
EP - 1013
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -