$\vec K$-band versus $\vec I$-band surface brightness fluctuations as distance indicators

Abstract

We evaluate the method of optical and infrared Surface Brightness Fluctuations (SBF) as a distance indicator and its application on 8-m class telescopes, such as the Very Large Telescope (VLT). The novelty of our approach resides in the development of Monte Carlo simulations of SBF observations incorporating realistic elliptical galaxy stellar population models, the effects induced by globular clusters and background galaxies, instrumental noise, sky background and PSF blurring. We discuss, for each band and in different observational conditions, the errors on distance measurements arising from stellar population effects, data treatment and observational constraints. With 8-m class telescopes, one can extend I-band SBF measurements out to 6000-10 000 km s-1. Integration times in the K-band are too expensive from the ground, due to the high infrared background for large-scale distance determination projects. Nevertheless ground-based K-band measurements are necessary to understand stellar population effects on the SBF calibration, and to prepare future space-based observations, where this band is more efficient.