X-ray scaling relations from a complete sample of the richest maxBCG clusters

Chong Ge, Ming Sun, Eduardo Rozo, Neelima Sehgal, Alexey Vikhlinin, William Forman, Christine Jones, Daisuke Nagai

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


We use a complete sample of 38 richest maxBCG clusters to study the ICM-galaxy scaling relations and the halo mass selection properties of the maxBCG algorithm, based on X-ray and optical observations. The clusters are selected from the two largest bins of optical richness in the Planck stacking work with the maxBCG richness N200 ≥ 78. We analyse their Chandra and XMM-Newton data to derive the X-ray properties of the ICM. We then use the distribution of P(X|N), X = TX, LX, YX, to study the mass selection P(M|N) of maxBCG. Compared with previous works based on the whole richness sample, a significant fraction of blended systems with boosted richness is skewed into this richest sample. Parts of the blended haloes are picked apart by the redMaPPer, an updated red-sequence cluster finding algorithm with lower mass scatter. Moreover, all the optical blended haloes are resolved as individual X-ray haloes, following the established LX−TX and LX−YX relations. We further discuss that the discrepancy between ICM-galaxy scaling relations, especially for future blind stacking, can come from several factors, including miscentring, projection, contamination of low-mass systems, mass bias, and covariance bias. We also evaluate the fractions of relaxed and cool core clusters in our sample. Both are smaller than those from SZ or X-ray selected samples. Moreover, disturbed clusters show a higher level of mass bias than relaxed clusters.

Original languageEnglish (US)
Pages (from-to)1946-1971
Number of pages26
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - 2019


  • Galaxies: clusters: general
  • Galaxies: clusters: intracluster medium
  • X-rays: galaxies: clusters

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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