Mass accretion rates of clusters of galaxies: CIRS and HeCS

¹ Dipartimento di Fisica, Università di Torino, via P. Giuria 1, 10125 Torino, Italy
e-mail: michele.pizzardo@unito.it
² Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Torino, via P. Giuria 1, 10125 Torino, Italy
³ Dipartimento di Fisica, Università di Trieste, via A. Valerio, 2, 34127 Trieste, Italy
⁴ Istituto Nazionale di Astrofisica (INAF), Sezione di Trieste, via G.B. Tiepolo 11, 34143 Trieste, Italy
⁵ Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Trieste, via A. Valerio 2, 34127 Trieste, Italy
⁶ OmegaLambdaTec GmbH, Lichtenbergstraße 8, 85748 Garching, Germany
⁷ Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA
⁸ Department of Physics and Astronomy, Western Washington University, Bellingham, WA 98225, USA
⁹ Dipartimento di Fisica e Astronomia, Alma Mater Studiorum Università di Bologna, via Gobetti 93/1, 40129 Bologna, Italy
¹⁰ Astrophysics and Space Science Observatory Bologna, via Gobetti 93/2 40129 Bologna, Italy
¹¹ Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy

Received: 23 May 2020
Accepted: 9 December 2020

Abstract

We use a new spherical accretion recipe tested on N-body simulations to measure the observed mass accretion rate (MAR) of 129 clusters in the Cluster Infall Regions in the Sloan Digital Sky Survey (CIRS) and in the Hectospec Cluster Survey (HeCS). The observed clusters cover the redshift range of 0.01 < z < 0.30 and the mass range of ∼10¹⁴ − 10¹⁵ h⁻¹ M_⊙. Based on three-dimensional mass profiles of simulated clusters reaching beyond the virial radius, our recipe returns MARs that agree with MARs based on merger trees. We adopt this recipe to estimate the MAR of real clusters based on measurements of the mass profile out to ∼3R₂₀₀. We use the caustic method to measure the mass profiles to these large radii. We demonstrate the validity of our estimates by applying the same approach to a set of mock redshift surveys of a sample of 2000 simulated clusters with a median mass of M₂₀₀ = 10¹⁴ h⁻¹ M_⊙ as well as a sample of 50 simulated clusters with a median mass of M₂₀₀ = 10¹⁵ h⁻¹ M_⊙: the median MARs based on the caustic mass profiles of the simulated clusters are unbiased and agree within 19% with the median MARs based on the real mass profile of the clusters. The MAR of the CIRS and HeCS clusters increases with the mass and the redshift of the accreting cluster, which is in excellent agreement with the growth of clusters in the ΛCDM model.