Brightest Cluster Galaxies Trace Weak Lensing Mass Bias and Halo Triaxiality in The Three Hundred Project

Ricardo Herbonnet*, Adrian Crawford*, Camille Avestruz*, Elena Rasia, Carlo Giocoli, Massimo Meneghetti, Anja von der Linden, Weiguang Cui, Gustavo Yepes

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Galaxy clusters have a triaxial matter distribution. The weak-lensing signal, an important part in cosmological studies, measures the projected mass of all matter along the line of sight, and therefore changes with the orientation of the cluster. Studies suggest that the shape of the brightest cluster galaxy (BCG) in the centre of the cluster traces the underlying halo shape, enabling a method to account for projection effects. We use 324 simulated clusters at four redshifts between 0.1 and 0.6 from ‘The Three Hundred Project’ to quantify correlations between the orientation and shape of the BCG and the halo. We find that haloes and their embedded BCGs are aligned, with an average ∼20 degree angle between their major axes. The bias in weak lensing cluster mass estimates correlates with the orientation of both the halo and the BCG. Mimicking observations, we compute the projected shape of the BCG, as a measure of the BCG orientation, and find that it is most strongly correlated to the weak-lensing mass for relaxed clusters. We also test a 2D cluster relaxation proxy measured from BCG mass isocontours. The concentration of stellar mass in the projected BCG core compared to the total stellar mass provides an alternative proxy for the BCG orientation. We find that the concentration does not correlate to the weak-lensing mass bias, but does correlate with the true halo mass. These results indicate that the BCG shape and orientation for large samples of relaxed clusters can provide information to improve weak-lensing mass estimates.
Original languageEnglish
Pages (from-to)2178-2193
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume513
Issue number2
Early online date11 Apr 2022
DOIs
Publication statusPublished - 1 Jun 2022

Keywords / Materials (for Non-textual outputs)

  • galaxies: clusters: general
  • galaxies: haloes
  • galaxies: structure
  • gravitational lensing: weak
  • methods: numerical

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