Detection of Radial Surface Brightness Fluctuations and Color Gradients in Elliptical Galaxies with the Advanced Camera for Surveys

We study surface brightness fluctuations (SBF) in a sample of 8 ellipticalgalaxies using Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) datadrawn from the Hubble Space Telescope (HST) archive. SBF magnitudes in theF814W bandpass, and galaxy colors from F814W, F435W, and F606W images -- whenavailable -- are presented. Galaxy surface brightness profiles are determinedas well. We present the first SBF--broadband color calibration for the ACS/WFCF814W bandpass, and (relative) distance moduli estimates for 7 of our galaxies. We detect and study in detail the SBF variations within individual galaxiesas a probe of possible changes in the underlying stellar populations.Inspecting both the SBF and color gradients in comparison to model predictions,we argue that SBF, and SBF-gradients, can in principle be used for unravelingthe different evolutionary paths taken by galaxies, though a more comprehensivestudy of this issue would be required. We confirm that the radial variation ofgalaxy stellar population properties should be mainly connected to the presenceof radial chemical abundance gradients, with the outer galaxy regions beingmore metal poor than the inner ones.Comment: 47 pages, 13 figures, ApJ, accepte