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Since the time of the Herschels, surveys of bright galaxies have provided
the foundations upon which much of observational cosmology rests.
Traditionally, these have been carried out on large-scale photographic plates,
and only with the recent Sloan Digital Sky Survey CCDs have been successfully
employed to image a significant portion of the northern sky.
Owing to the revolutionary nature of the GAIA mission, the GAIA Galaxy Survey
has little in common with previous galaxy survey projects, its main
advantages being the nearly all-sky coverage, a well-defined selection
function and a very high angular resolution.
The overall measurement capabilities expected from the GAIA Galaxy Survey are
described in the following Chapters.
For the time being, and for a general discussion of its scientific objectives,
it suffices to say that multi-color, multi-epoch photometry at a resolution
better than 0.4 arcsec for some 3 million galaxies will be
obtained.
Growth of structure in the Universe is believed to proceed from small-amplitude
perturbations at very early times. Their growth from the radiation-dominated
era to the present has been extensively studied, particularly in the context
of the popular hierarchical clustering scenario. Many aspects of this picture
are fairly well-established. Others are subject of active definition through
redshift and imaging surveys of galaxies, and the microwave background
experiments. There are several aspects of this research which require very
wide area imaging surveys with high angular resolution to provide
high-reliability catalogues of galaxies and quasars extending to low Galactic
latitudes. Here GAIA will contribute uniquely, by detecting and providing
multi-color surface photometry at high angular resolution for all
sufficiently high surface brightness galaxies. This provides a valuable and
unique dataset at two levels: for study of the large-scale structure of the
Local Universe probed through the spatial distribution of galaxies and for
statistical studies of the photometric structure of their central regions.
Subsections
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Up: 3. Scientific Case for
Previous: 3.2.3 Point Spread Function
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Mattia Vaccari
2000-12-05