Splashback Radius of Dark Matter Halo

Introduction

• Read the introduction by Benedikt Diemer on his webpage: > “…A more natural halo boundary is provided by the splashback radius, \(R_{\rm sp}\), the radius where particles reach the apocenter of their first orbit after infall…Particles at the apocenter of their first orbit pile up due to their low radial velocity, creating a caustic that manifests itself as a sharp drop in the density profile. This so-called splashback radius represents a clear boundary between matter orbiting in the halo and matter on a first infall toward the halo.”

Reviews

• Walker et al. 2018 - The physics of galaxy cluster outskirts
  • See Section 1.1 and Figure 1.

Theoretical consideration

• Dimmer & Kravtsov 2014 - Dependence of the Outer Density Profiles of Halos on Their Mass Accretion Rate
  • Important
• Adhikari, Dalal & Chamberlain 2014 - Splashback in accreting dark matter halos
• More, Diemer & Kravtsov - The Splashback Radius as a Physical Halo Boundary and the Growth of Halo Mass
• Shi 2016 - The outer profile of dark matter haloes: an analytical approach
• Diemer 2017 - The Splashback Radius of Halos from Particle Dynamics. I. The SPARTA Algorithm
• Diemer et al. 2017 - The Splashback Radius of Halos from Particle Dynamics. II. Dependence on Mass, Accretion Rate, Redshift, and Cosmology
  • Important
• Mansfield, Kravtsov & Diemer 2017 - Splashback Shells of Cold Dark Matter Halos
  • Shellfish: SHELL Finding In Spheroidal Halos
• Busch & White 2017 - Assembly bias and splashback in galaxy clusters
  • Important
• Snaith et al. 2017 - Haloes at the ragged edge: the importance of the splashback radius
• Adhikari et al. 2018 - Splashback in galaxy clusters as a probe of cosmic expansion and gravity
• Okumura et al. 2018 - Splashback radius of nonspherical dark matter halos from cosmic density and velocity fields
• Renneby, Hilbert & Angulo 2018 - Halo mass and weak galaxy-galaxy lensing profiles in rescaled cosmological N-body simulations

Observational constraints

(Figure from Chang et al. 2018. Claimed detection of splashback radius around redMaPPer clusters using DES)

• Niikura et al. 2015 - Detection of universality of dark matter profile from Subaru weak lensing measurements of 50 massive clusters
  • No detection of splashback signature.
• More et al. 2016 - Detection of the Splashback Radius and Halo Assembly Bias of Massive Galaxy Clusters
  • Claim detection: “We show that the projected number density profiles of Sloan Digital Sky Survey photometric galaxies around galaxy clusters display strong evidence for the splashback radius, a sharp halo edge corresponding to the location of the first orbital apocenter of satellite galaxies after their infall.”
• Umetsu & Diemer 2017 - Lensing Constraints on the Mass Profile Shape and the Splashback Radius of Galaxy Clusters
  • Place lower limit.
• Baxter et al. 2017 - The Halo Boundary of Galaxy Clusters in the SDSS
  • Unclear, results are model sensitive
• Nishizawa et al. 2018 - First results on the cluster galaxy population from the Subaru Hyper Suprime-Cam survey. II. Faint end color-magnitude diagrams and radial profiles of red and blue galaxies at 0.1 < z < 1.1
  • Detection using galaxy number density profiles (Fig 6)
• Chang et al. 2018 - The Splashback Feature around DES Galaxy Clusters: Galaxy Density and Weak Lensing Profiles
  • Important Claim detection: “we find strong evidence of a splashback-like steepening of the galaxy density profile”
• Contigiani, Hoekstra & Bahe 2018 - Weak lensing constraints on splashback around massive clusters
  • Unclear, “We do not detect a significant steepening”, but gives a constraint.
• Shin et al. 2018 arXiv:1811 - Measurement of the Splashback Feature around SZ-selected Galaxy Clusters with DES, SPT and ACT
  • Detection using galaxy number density profile around SZ selected clusters
  • R_sp consistent with prediction from simulation, in different with optically selected clusters
  • Blue galaxies show just power law profile without splashback signiture, consistent with first infall

About accretion rate

• De Boni et al. 2016 - The Mass Accretion Rate of Galaxy Clusters: A Measurable Quantity
• De Boni 2016 - Using the Outskirts of Galaxy Clusters to Determine Their Mass Accretion Rate

General discussion about mass density profiles

• Shi 2016b - Locations of accretion shocks around galaxy clusters and the ICM properties: insights from self-similar spherical collapse with arbitrary mass accretion rates
• Trevisan, Mamon & Stalder 2017 - Group galaxy number density profiles far out: Is the __one-halo’ term NFW out to >10 virial radii?
• Fong et al. 2018 - Prospects for determining the mass distributions of galaxy clusters on large scales using weak gravitational lensing
• Osato et al. 2018 - Strong orientation dependence of surface mass density profiles of dark haloes at large scales
  • “While the orientation dependence at small scales is ascribed to the halo triaxiality, our results indicate even stronger orientation dependence in the so-called two-halo regime”