RASS-SDSS Galaxy cluster survey

Free access article

Issue		A&A Volume 445, Number 1, January I 2006


Page(s)		29 - 42
Section		Cosmology (including clusters of galaxies)
DOI		http://dx.doi.org/10.1051/0004-6361:20052954

A&A 445, 29-42 (2006)
DOI: 10.1051/0004-6361:20052954

IV. A ubiquitous dwarf galaxy population in clusters

P. Popesso¹, A. Biviano², H. Böhringer¹ and M. Romaniello³

¹ Max-Planck-Institut fur extraterrestrische Physik, 85748 Garching, Germany
e-mail: ppopesso@eso.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

(Received 1 March 2005 / Accepted 8 June 2005 )

Abstract
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 u-r colors. The late-type LF is well fitted by a single Schechter function with a steep slope ( $\alpha=-2.0$ 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 $\sim$ 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

SIMBAD Objects

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.