Testing the Large-scale Environments of Cool-core and Non-cool-core Clusters with Clustering Bias

Elinor Medezinski, Nicholas Battaglia, Jean Coupon, Renyue Cen, Massimo Gaspari, Michael A. Strauss, David N. Spergel

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


There are well-observed differences between cool-core (CC) and non-cool-core (NCC) clusters, but the origin of this distinction is still largely unknown. Competing theories can be divided into internal (inside-out), in which internal physical processes transform or maintain the NCC phase, and external (outside-in), in which the cluster type is determined by its initial conditions, which in turn leads to different formation histories (i.e., assembly bias). We propose a new method that uses the relative assembly bias of CC to NCC clusters, as determined via the two-point cluster-galaxy cross-correlation function (CCF), to test whether formation history plays a role in determining their nature. We apply our method to 48 ACCEPT clusters, which have well resolved central entropies, and cross-correlate with the SDSS-III/BOSS LOWZ galaxy catalog. We find that the relative bias of NCC over CC clusters is b = 1.42 ± 0.35 (1.6σ different from unity). Our measurement is limited by the small number of clusters with core entropy information within the BOSS footprint, 14 CC and 34 NCC clusters. Future compilations of X-ray cluster samples, combined with deep all-sky redshift surveys, will be able to better constrain the relative assembly bias of CC and NCC clusters and determine the origin of the bimodality.

Original languageEnglish (US)
Article number54
JournalAstrophysical Journal
Issue number1
StatePublished - Feb 10 2017

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • cosmology: observations
  • dark matter
  • galaxies: clusters
  • large-scale structure of universe


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