The contribution of halos with different mass ratios to the overall growth of cluster-sized halos

Doron Lemze, Marc Postman, Shy Genel, Holland C. Ford, Italo Balestra, Megan Donahue, Daniel Kelson, Mario Nonino, Amata Mercurio, Andrea Biviano, Piero Rosati, Keiichi Umetsu, David Sand, Anton Koekemoer, Massimo Meneghetti, Peter Melchior, Andrew B. Newman, Waqas A. Bhatti, G. Mark Voit, Elinor MedezinskiAdi Zitrin, Wei Zheng, Tom Broadhurst, Matthias Bartelmann, Narciso Benitez, Rychard Bouwens, Larry Bradley, Dan Coe, Genevieve Graves, Claudio Grillo, Leopoldo Infante, Yolanda Jimenez-Teja, Stephanie Jouvel, Ofer Lahav, Dan Maoz, Julian Merten, Alberto Molino, John Moustakas, Leonidas Moustakas, Sara Ogaz, Marco Scodeggio, Stella Seitz

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


We provide a new observational test for a key prediction of the ΛCDM cosmological model: the contributions of mergers with different halo-to-main-cluster mass ratios to cluster-sized halo growth. We perform this test by dynamically analyzing 7 galaxy clusters, spanning the redshift range 0.13 < z c < 0.45 and caustic mass range 0.4-1.5 M , with an average of 293 spectroscopically confirmed bound galaxies to each cluster. The large radial coverage (a few virial radii), which covers the whole infall region, with a high number of spectroscopically identified galaxies enables this new study. For each cluster, we identify bound galaxies. Out of these galaxies, we identify infalling and accreted halos and estimate their masses and their dynamical states. Using the estimated masses, we derive the contribution of different mass ratios to cluster-sized halo growth. For mass ratios between ∼0.2 and ∼0.7, we find a ∼1σ agreement with ΛCDM expectations based on the Millennium simulations I and II. At low mass ratios, ≲ 0.2, our derived contribution is underestimated since the detection efficiency decreases at low masses, ∼2 × 1014 M . At large mass ratios, ≳ 0.7, we do not detect halos probably because our sample, which was chosen to be quite X-ray relaxed, is biased against large mass ratios. Therefore, at large mass ratios, the derived contribution is also underestimated.

Original languageEnglish (US)
Article number91
JournalAstrophysical Journal
Issue number2
StatePublished - Oct 20 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • dark matter
  • galaxies: kinematics and dynamics


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