Optical Surface Brightness Fluctuations of shell galaxies towards 100 Mpc

TL;DR

This study demonstrates that optical surface brightness fluctuations can be reliably measured in distant shell galaxies up to 100 Mpc using HST imaging, enabling accurate distance estimates and contributing to Hubble constant measurements.

Contribution

The paper introduces a new calibration of SBF magnitudes for the F814W filter and extends SBF distance measurement techniques to galaxies at 100 Mpc.

Findings

Optical SBFs can be measured at distances ≥ 100 Mpc with HST.

Derived Hubble constant H0 = 76 ± 6 km/s/Mpc from SBF distances.

Achieved ~8% statistical and ~6% systematic uncertainties in distance measurements.

Abstract

We measure F814W Surface Brightness Fluctuations (SBF) for a sample of distant shell galaxies with radial velocities ranging from 4000 to 8000 km/s. The distance at galaxies is then evaluated by using the SBF method. For this purpose, theoretical SBF magnitudes for the ACS@HST 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 $\bar{M}_{F814W}$ versus $(F475W-F814W)_0$ calibration and we extend the previous I-band versus $(B-I)_0$ color relation to colors $(B-I)_{0}\leq 2.0$ mag. Coupling our SBF measurements with the theoretical calibration we derive distances with a statistical uncertainty of $\sim 8%$, and systematic error of $\sim 6 %$. The procedure developed to analyze data ensures that the indetermination due to possible unmasked residual shells is well below $\sim 12 %$. The results suggest that \emph{optical} SBFs can be measured at $d \geq 100 Mpc$ with ACS@HST imaging. SBF-based distances coupled with recession velocities corrected for peculiar motion, allow us obtain $H_{0} = 76 \pm 6$ (statistical) $\pm 5$ (systematic) km/s/Mpc.