Skip to main content

Infrared surface brightness fluctuactions - distance scale and constraints on extragalactic stellar populations


Research objectives and content
We propose to calibrate and apply infrared (1-2.5pim) surface brightness fluctuation (SBF) measurements of galaxies as a cosmological distance indicator, addressing the problem thoroughly from an observational perspective using several telescopes including the Hubble Space Telescope (HST) and Keck 10-m telescopes and from a theoretical perspective using the most advanced galaxian stellar population models developed at the Institut d'Astrophysique de Paris. Unlike most cosmological distance indicators, surface brightness fluctuation (SBF) measurements are appealing because of their well-understood physical basis; SBF work at optical distances has been developed as a useful distance indicator over the last 10 yr. As SBFs of ellipticals are dominated by late-type stars, infrared (IR) measurements with the Keck telescopes offer the potential to measure distances 2-3 times as far as previous optical SBF work. Using state-of-the-art stellar population models, we will investigate the predicted behavior of IR SBFs with stellar population variations and compare with observations. A primary motivation for this project is to provide the European community with the best tools for exploiting some of the outstanding capabilities of the upcoming Very Large Telescope (VLT). Distance measurements out to 100 h-1 Mpc and consequently, a value of the Hubble constant uncontaminated by local peculiar velocities seem within reach.
Training content (objective benefit and expected impact)
Beyond the immediate scientific return described above, the significant improvement of stellar population models widely used by the European cosmological community will have considerable impact for exploiting the capacilities of the ESO/VLT that will be operational in 1998. Links with industry / industrial relevance (22).
The project has indirect implication for industry through the definition of new requirements for future infrared instruments.

Funding Scheme

RGI - Research grants (individual fellowships)


Boulevard Arago 98 Bis
75014 Paris

Participants (1)

Not available