Optical Surface Brightness Fluctuations of Shell Galaxies toward 100 Mpc

We measure F814W surface brightness fluctuations (SBFs) for a sample of distant shell galaxies with radial velocities ranging from 4000 to 8000 km s −1 . The distance at galaxies is then evaluated by using the SBF method. For this purpose, theoretical SBF magnitudes for the HST ACS filters are computed for single-burst stellar populations covering a wide range of ages ( t = 1.5–14 Gyr) and metallicities ( Z = 0.008–0.04). Using these stellar population models, we provide the first F814W versus (F 475W − F 814W) 0 calibration and we extend the previous M 1 versus ( B − I ) 0 color relation to colors ( B − I ) 0 ⩽ 2.0 mag. Coupling our SBF measurements with the theoretical calibration we derive distances with a statistical uncertainty of ~8%, and systematic error of ~6%. The procedure developed to analyze data ensures that the indetermination due to possible unmasked residual shells is well below ~12%. The results suggest that optical SBFs can be measured at d ⩾ 100 Mpc with HST ACS imaging. SBF-based distances coupled with recession velocities corrected for peculiar motion, allow us obtain H 0 = 76 ± 6 (statistical) ±5 (systematic) km s −1 Mpc −1 .