A Study of Dwarf Galaxies in Five Rich Clusters III: Final Results
Abstract
A population of 760 dwarf galaxy candidates have been found in five intermediate redshift clusters using ACS Investigation Team data. The clusters studied are A1689 (z=0.1832), A1703 (z=0.2580), A2218 (z=0.1756), CL0024+16 (z=0.395), and MS1358+62 (z=0.328). In order to alleviate uncertainty due to obscuration of dwarfs by larger galaxies, an obstacle especially pervasive in the dense cluster centers, we have subtracted the light from giant elliptical galaxies. This was accomplished through modeling of elliptical isophotes using a nonlinear least-squares algorithm capable of fitting light from up to five galaxies at once. Cluster membership was determined using SExtractor and Bayesian Photometric Redshifts (BPZ). The photometrically assigned redshifts were compared to published spectroscopic redshifts and revealed an RMS error of Δz=0.068(1+zspec). Completeness was tested through the addition onto our images of model dE galaxies with effective radii and colors similar to the detected population. Running our detection apparatus on these modified images tells us about the completeness of our search in terms of color, luminosity, and cluster location. The final population of dwarf galaxies was used to create completeness corrected r-band luminosity functions (LF) for each galaxy cluster. The data were better fit using a Gaussian function on the bright end combined with a Schechter function on the faint end than with a Schechter function alone. Analysis of these LF's also includes a decomposition by both color and clustercentric radii. A paucity of dwarf galaxies was found in the central regions of these clusters. Dynamical implications of these results are discussed. ACS was developed under NASA contract NAS5-32865, and this research was supported by NASA grant NAG5-7697.
- Publication:
-
American Astronomical Society Meeting Abstracts #213
- Pub Date:
- January 2009
- Bibcode:
- 2009AAS...21341905R