Evolution of the red sequence giant to dwarf ratio in galaxy clusters out to z ∼ 0.5

C. Bildfell, H. Hoekstra, A. Babul, D. Sand, M. Graham, J. Willis, S. Urquhart, A. Mahdavi, C. Pritchet, D. Zaritsky, J. Franse, P. Langelaan

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

We analyse deep g′ and r′ band data of 97 galaxy clusters imaged with MegaCam on the Canada-France-Hawaii telescope. We compute the number of luminous (giant) and faint (dwarf) galaxies using criteria based on the definitions of de Lucia et al. Due to excellent image quality and uniformity of the data and analysis, we probe the giant-to-dwarf ratio (GDR) out to z ∼ 0.55. With X-ray temperature (T x) information for the majority of our clusters, we constrain, for the first time, the T x-corrected giant and dwarf evolution separately. Our measurements support an evolving GDR over the redshift range 0.05 ≤ z ≤ 0.55. We show that modifying the (g′ - r′), mr′ and K-correction used to define dwarf and giant selection does not alter the conclusion regarding the presence of evolution. We parametrize the GDR evolution using a linear function of redshift (GDR =αz+β) with a best-fitting slope of α = 0.88 ± 0.15 and normalization β = 0.44 ± 0.03. Contrary to claims of a large intrinsic scatter, we find that the GDR data can be fully accounted for using observational errors alone. Consistently, we find no evidence for a correlation between GDR and cluster mass (via T x or weak lensing). Finally, the data suggest that the evolution of the GDR at z < 0.2 is driven primarily by dry merging of the massive giant galaxies, which when considered with previous results at higher redshift, suggests a change in the dominant mechanism that mediates the GDR.

Original languageEnglish (US)
Pages (from-to)204-221
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume425
Issue number1
DOIs
StatePublished - Sep 1 2012

Keywords

  • Galaxies: clusters: general
  • Galaxies: elliptical and lenticular, cD
  • Galaxies: evolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Bildfell, C., Hoekstra, H., Babul, A., Sand, D., Graham, M., Willis, J., Urquhart, S., Mahdavi, A., Pritchet, C., Zaritsky, D., Franse, J., & Langelaan, P. (2012). Evolution of the red sequence giant to dwarf ratio in galaxy clusters out to z ∼ 0.5. Monthly Notices of the Royal Astronomical Society, 425(1), 204-221. https://doi.org/10.1111/j.1365-2966.2012.21426.x