As part of the Advanced Camera for Survey(ACS) Virgo Cluster Survey, we have measured Surface Brightness Fluctuations (SBF) in a sample of 100 early-type Virgo galaxies. Distances derived from these measurements are needed to explore the three-dimensional structure of the Virgo Cluster, study the intrinsic parameters of globular clusters associated with the program galaxies, and compare with the galaxy distances derived from globular cluster luminosity functions. Our SBF measurements have been performed in the F850LP bandpass of the Wide Field Channel of the ACS on the Hubble Space Telescope. These are the first measurements of this kind, and we present the first SBF calibration for this bandpass. The measured fluctuations depend on galaxy stellar population variations, which we quantify by galaxy color (g475 − z850)0, where g475 and z850 are the galaxy magnitudes, respectively, in the F475W and F850LP ACS filters. We derive the following calibration for the absolute SBF magnitude M850: M850 = −2.06 ± 0.04 + (2.0 ± 0.2) × [(g475 − z850)0 − 1.3] in the range 1.3 < (g475 − z850)0 ≤ 1.6, and M850 = −2.06 ± 0.04 + (0.9 ± 0.2) × [(g475 − z850)0 − 1.3] in the range 1.0 ≤ (g475 − z850)0 ≤ 1.3. The quoted zero-point uncertainty here includes all sources of internal error; there is an additional systematic uncertainty of ∼0.15 mag, due to the uncertainty in the distance scale calibration. Physically, the two different color regimes correspond to different galaxy types: giant ellipticals and S0s at the red end, and early-type dwarfs at the blue end. For the first time in SBF studies, we are able to provide a firm empirical calibration of SBF in early–type dwarf galaxies. Our results agree with stellar population model predictions from Bruzual & Charlot (2003) in the range 1.3 < (g475−z850)0 ≤ 1.6, while our empirical slope is somewhat steeper than the theoretical prediction in the range 0.9 ≤ (g475 − z850)0 ≤ 1.3.

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Also archived in: arXiv: astro-ph/0506314 v2 15 Jun 2005 We thank Stephane Charlot for providing theoretical stellar population models in the ACS filters and Gerhard Meurer for useful discussions. Support for program GO-9401 was provided through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. ACS was developed under NASA contract NAS 5-32865. S.M. and J.P.B. acknowledge additional support from NASA grant NAG5-7697 to the ACS Team. P.C. acknowledges support provided by NASA LTSA grant NAG5-11714. M.J.W. acknowledges support through NSF grant AST-0205960. D.M. acknowledges support provided by NSF grants AST-0071099, AST-0206031, AST-0420920 and AST-0437519, by NASA grant NNG04GJ48G, and by grant HST-AR-09519.01-A from STScI. M.M. acknowledges support from the Sherman M. Fairchild foundation. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.ISSN:1538-4357 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus