deep infrared imaging surveys have revealed a class of faint galaxies which exhibit very red optical-to-ir colors (r-k>6). little is known about these mysterious objects due to their extreme optical faintness. one exciting possibility is that these are galaxies with an evolved population of stars at high redshift. if the red colors are due to the presence of an old stellar population, it requires a source redshift of about 2. the existence of evolved galaxies at such a high redshift has profound implications for our understanding of galaxy formation and may place interesting constraints on the geometry of the universe. alternatively, these red colors could be due to the presence of a highly reddened component present within galaxies at a more modest redshift. this could be either a reddened agn or a nuclear star burst. we request observations with the isocam using the lw1 and lw2 bands to determine if these objects are old galaxies at high redshift or a new class of obscured agn. for the first scenario, isocam colors will detect the characteristic roll over of the spectral energy distribution around 4 microns (1.6 microns in the rest frame). if instead they are a new class of reddened agn, the spectral energy distributions should continue to rise from 2-8 microns. without iso data it is not possible to extend the spectral energy distributions of these source to long enough wavelengths to test these models.
Instrument
CAM01
Temporal Coverage
1996-04-09T02:37:23Z/1996-12-15T03:22:57Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
