Volume 445, Number 1, January I 2006
|Page(s)||29 - 42|
|Section||Cosmology (including clusters of galaxies)|
|Published online||13 December 2005|
RASS-SDSS Galaxy cluster survey
IV. A ubiquitous dwarf galaxy population in clusters
Max-Planck-Institut fur extraterrestrische Physik, 85748 Garching, Germany e-mail: firstname.lastname@example.org
2 INAF – Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34131, Trieste, Italy
3 European Southern Observatory, Karl Scharzschild Strasse 2, 85748, Germany
Accepted: 8 June 2005
We analyze the Luminosity Functions (LFs) of a subsample of 69 clusters from the RASS-SDSS galaxy cluster catalog. When calculated within the cluster physical sizes, given by r200 or r500, all the cluster LFs appear to have the same shape, well fitted by a composite of two Schechter functions with a marked upturn and a steepening at the faint-end. Previously reported cluster-to-cluster variations of the LF faint-end slope are due to the use of a metric cluster aperture for computing the LF of clusters of different masses. We determine the composite LF for early- and late-type galaxies, where the typing is based on the galaxy colors. The late-type LF is well fitted by a single Schechter function with a steep slope ( in the r band, within r200). The early-type LF instead cannot be fitted by a single Schechter function, and a composite of two Schechter functions is needed. The faint-end upturn of the global cluster LF is due to the early-type cluster galaxies. The shape of the bright-end tail of the early-type LF does not seem to depend upon the local galaxy density or the distance from the cluster center. The late-type LF shows a significant variation only very near the cluster center. On the other hand, the faint-end tail of the early-type LF shows a significant and continuous variation with the environment. We provide evidence that the process responsible for creating the excess population of dwarf early type galaxies in clusters is a threshold process that occurs when the density exceeds ∼500 times the critical density of the Universe. We interpret our results in the context of the “harassment” scenario, where faint early-type cluster galaxies are predicted to be the descendants of tidally-stripped late-type galaxies.
Key words: galaxies: clusters: general / galaxies: luminosity function, mass function
© ESO, 2005
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.