Recent arrival of faint cluster galaxies on the red sequence: luminosity functions from 119���deg²of CFHTLS

Abstract

The global star formation rate has decreased significantly since z∼ 1, for reasons that are not well understood. Red‐sequence galaxies, dominating in galaxy clusters, represent the population that have had their star formation shut off, and may therefore be the key to this problem. In this work, we select 127 rich galaxy clusters at 0.17 ≤z≤ 0.36, from 119 deg2 of the Canada–France–Hawaii Telescope Legacy Survey (CFHTLS) optical imaging data, and construct the r′‐band red‐sequence luminosity functions (LFs). We show that the faint end of the LF is very sensitive to how red‐sequence galaxies are selected, and an optimal way to minimize the contamination from the blue cloud is to mirror galaxies on the redder side of the colour–magnitude relation. The LFs of our sample have a significant inflexion centred at , suggesting a mixture of two populations. Combining our survey with low‐redshift samples constructed from the Sloan Digital Sky Survey, we show that there is no strong evolution of the faint end of the LF (or the red‐sequence dwarf‐to‐giant ratio) over the redshift range 0.2 ≲z≲ 0.4, but from z∼ 0.2 to ∼0 the relative number of red‐sequence dwarf galaxies has increased by a factor of ∼3, implying a significant build‐up of the faint end of the cluster red sequence over the last 2.5 Gyr.

Weak-lensing-inferred scaling relations of galaxy clusters in the RCS2: mass-richness, mass-concentration, mass-bias, and more

“…Galaxies clusters are identified using a modified version of the algorithm presented in Lu et al (2009). This is a simplified version of the Gladders & Yee (2005) red-sequence cluster-finding method.…”

The red-sequence of 72 WINGS local galaxy clusters

“…High-z studies find a deficiency of faint red galaxies in comparison to local galaxy clusters, as the luminous-to-faint ratio is seen to evolve from higher values at high-z to lower values at low-z (see, among others, De Lucia et al 2004;Tanaka et al 2005;De Lucia et al 2007;Stott et al 2007;Lu et al 2009;Rudnick et al 2009;Stott et al 2009;Capozzi et al 2010;and Andreon 2008;Crawford et al 2009 for different conclusions). This is generally interpreted as evidence of a large number of relatively faint galaxies having moved to the RS only recently, most probably due to the quenching of star formation caused by the highdensity environment.…”

Abell 1758N from an optical point of view: new insights on a merging cluster with diffuse radio emission

“…therein). In particular, the difference between passive and starforming galaxies is larger in g -r color than in r -i color (see Lu et al 2009, their Fig. 6) but r -i color has a much smaller scatter (Lopes 2007, his Fig.…”

“…4.1, these galaxies seem to trace the whole A1758N system and not its substructure. When more than two colors are available, it is very effective to select cluster galaxies in the color-color space (Goto et al 2002) and both SDSS r -i and g -r colors are generally used at z < 0.4 (Lu et al 2009;Lopes 2007: his Eq. (1) and refs.…”