The Universe

Galactic survey

At the beginning of the mission, Spitzer will hold a series of imaging surveys in the mid and far infrared. Census Deep and a small region of space, including one centered on the Hubble Deep Field (English) , study the young and distant universe with redshifts of about 5, which corresponds to about 12 billion years.

 Shallower surveys will be conducted over larger areas, which will greatly increase the number of cataloged infrared galaxies. A survey will cover about 70 square degrees, or 350 times the area of ​​the full moon, and come to a redshift of 2.5, corresponding to about ten billion light years. This survey will reveal more than 2 million galaxies, some 30,000 galaxies per square degree. And like any extragalactic survey, the Spitzer data will be supplemented with other observation programs at other wavelengths and other space and ground telescopes.

Origin and Evolution of Galaxies

At a cosmological redshift of 5, the visible light emitted by young galaxies is redshifted to near-infrared, which places it within the Spitzer observational regime. Astronomers will use this to observe protogalaxies with dust rising in the young and distant Universe. Examining the properties of galaxies with different redshifts, or with different ages, scientists will trace the history of star formation rate as a function of the environment, and try to explain why the overall rate of star formation was much higher for 7 billion years now. These data will also study the spatial distribution of galaxies and the fraction of them appears in clusters. The Spitzer data, combined with X-ray data, will also study the contribution of galaxies "starburst" and active galactic nuclei to the global infrared luminosity.

Cosmic Infrared Background

The cosmic infrared background brightness is a very diffuse and weak, presumably produced by the juxtaposition of a very large number of galaxies that are too faint to be detected individually. Studying the intensity of the CIRB at different wavelengths, astronomers can interpret the history of star formation, galaxy formation and the presence or absence of dust in the first generation of galaxies. Spitzer not only confirms the recent detection of this background radiation, but will characterize the sources that produce it.

Infrared Optically Unidentified Sources

It is well known that some celestial objects release more of their radiation at certain wavelengths. Spitzer is sure to discover unusual infrared sources with no optical identification. Spitzer spectroscopic measurements will allow astronomers to obtain the redshift, and therefore the distance of these mysterious objects. The Spitzer data will be combined with observations at other wavelengths, like X-rays and radio waves to help study these newly discovered sources.

Victims Discoveries

The combination of high sensitivity, high observing efficiency, large format infrared detectors and a long life cryogenic represent a giant leap beyond current capabilities. This powerful combination will produce a rich legacy of scientific results that will be studied for decades. As history has repeatedly shown, astronomers expect the unexpected chance discoveries of unanticipated phenomena.