Diffuse Optical Light in Galaxy Clusters I: Abell 3888

• Main Authors: Krick, J. E, Bernstein, R. A, Pimbblet, K. A
• Format: Journal Article
• Language: English
• Published: 20-09-2005
• Subjects: Physics - Astrophysics of Galaxies; Physics - Cosmology and Nongalactic Astrophysics; Physics - Earth and Planetary Astrophysics; Physics - High Energy Astrophysical Phenomena; Physics - Instrumentation and Methods for Astrophysics; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.astro-ph/0509609

Astron.J.131:168-184,2006 We are undertaking a program to measure the characteristics of the
intracluster light (total flux, profile, color, and substructure) in a sample
of 10 galaxy clusters with a range of cluster mass, morphology, and redshift.
We present here the methods and results for the first cluster in that sample,
A3888. We have identified an intracluster light (ICL) component in A3888 in V
and r that contains 13\pm5% of the total cluster light and extends to
700h_{70}^{-1}kpc (~0.3 r_{200}) from the center of the cluster. The ICL color
in our smallest radial bin is V-r = 0.3 \pm 0.1, similar to the central cluster
ellipticals. The ICL is redder than the galaxies at 400 < r < 700h_{70}^{-1}kpc
although the uncertainty in any one radial bin is high. Based on a comparison
of V-r color with simple stellar models, the ICL contains a component which
formed more than 7 Gyr ago (at z > 1), coupled with a high metallicity
(1.0Z_{\odot} < Z_{ICL} \la 2.5Z_{\odot}), and a more centralized component
which contains stars formed within the past 5 Gyr (at z ~ 1). The profile of
the ICL can be roughly fit by a shallow exponential in the outer regions and a
steeper exponential in the central region. We also find a concentration of
diffuse light around a small group of galaxies 1.4h_{70}^{-1}Mpc from the
center of the cluster. In addition, we find 3 low surface brightness features
near the cluster center which are blue (V-r = 0.0) and contain a total flux of
0.1M*. Based on these observations and X-ray and galaxy morphology, we suggest
that this cluster is entering a phase of significant merging of galaxy groups
in the core, whereupon we expect the ICL fraction to grow significantly with
the formation of a cD galaxy as well as the in-fall of groups.