Evidence of Halo Assembly Bias in Massive Clusters

Hironao Miyatake; Surhud More; Masahiro Takada; David N Spergel; Rachel Mandelbaum; Eli S Rykoff; Eduardo Rozo

doi:10.1103/PhysRevLett.116.041301

Evidence of Halo Assembly Bias in Massive Clusters

Phys Rev Lett. 2016 Jan 29;116(4):041301. doi: 10.1103/PhysRevLett.116.041301. Epub 2016 Jan 25.

Authors

Hironao Miyatake^{1

2

3}, Surhud More², Masahiro Takada², David N Spergel^{1

2}, Rachel Mandelbaum⁴, Eli S Rykoff^{5

6}, Eduardo Rozo⁷

Affiliations

¹ Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton New Jersey 08544, USA.
² Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo, Chiba 277-8583, Japan.
³ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA.
⁴ Department of Physics, McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
⁵ Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA.
⁶ SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
⁷ Department of Physics, University of Arizona, 1118 E 4th St, Tucson, Arizona 85721, USA.

PMID: 26871319
DOI: 10.1103/PhysRevLett.116.041301

Abstract

We present significant evidence of halo assembly bias for SDSS redMaPPer galaxy clusters in the redshift range [0.1, 0.33]. By dividing the 8,648 clusters into two subsamples based on the average member galaxy separation from the cluster center, we first show that the two subsamples have very similar halo mass of M_{200m}≃1.9×10^{14} h^{-1}M_{⊙} based on the weak lensing signals at small radii R≲10 h^{-1}Mpc. However, their halo bias inferred from both the large-scale weak lensing and the projected autocorrelation functions differs by a factor of ∼1.5, which is a signature of assembly bias. The same bias hypothesis for the two subsamples is excluded at 2.5σ in the weak lensing and 4.4σ in the autocorrelation data, respectively. This result could bring a significant impact on both galaxy evolution and precision cosmology.