TPF-I SWG Report - Exoplanet Exploration Program - NASA

C HAPTER 3
Figure 3-9: Simulated images of a M51-type galaxy at z = 3 as observed with JWST (left) and Darwin
(right).
The Faint Infra Red Extra-galactic Survey (FIRES, Franx et al. 2000), a very deep infrared survey
centered on the Hubble Deep Field South using the Infrared Spectrometer and Array Camera (ISAAC)
instrument mounted on the Very Large Telescope (VLT) (Moorwood 1997) demonstrates that there will
be plenty of targets to investigate with Darwin/TPF-I. With integration times of more than 33 hours for
each of the infrared bands (J, H, and K), limiting AB magnitudes of 26.0, 24.9, and 24.5, respectively, are
reached (Labbé et al. 2003). Recently, this field has been imaged at 3 to 8 μm with the Infrared Array
Camera (IRAC) on the Spitzer Space Telescope with the aim of accurately determining stellar masses for
distant red galaxies (see Fig. 3-8 and Labbé et al. 2005). From these studies, we conclude that, for the
brighter objects, it is possible to obtain good images with a signal-to-noise ratio of 50 within integration
times of 25–50 hours using Darwin/TPF-I.
Darwin/TPF-I will resolve individual OB associations, massive star clusters, and their associated giant
HII regions. By observing multiple fields, interferometric maps of entire galaxies can be obtained at
selected redshifts. By carefully selecting targets of a specific type, the evolution of galaxy structures can
be tracered as functions of redshift and environment. The evolution of metallicity with cosmic age (and
redshift) can be mapped using the various molecular tracers, ices, PAH bands, and noble-gas lines that
fall into the pass-band of Darwin/TPF-I.
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