Identification of Luminous Infrared Galaxies at 1 z 2.5aaBased on observations made with the Spitzer Space Telescope, operated by the Jet Propulsion Laboratory under NASA contract 1407. bbBased on observations collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. ccBased on observations collected at the Canada-France-Hawaii Telescope, which is operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique and the University of Hawaii. ddBased on observations obtained at Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement with the National Science Foundation. eeBased on observations collected at the German-Spanish Astronomical Center, Calar Alto, operated jointly by Max-Planck-Institut fr Astronomie and Instituto de Astrofsica de Andalucia (CSIC). ffBased on
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We present preliminary results on 24 m detections of luminous infrared galaxies at z 1 with the Multiband Imaging Photometer for Spitzer (MIPS). Observations were performed in the Lockman Hole and the Extended Groth Strip (EGS) and were supplemented by data obtained with the Infrared Array Camera (IRAC) between 3 and 9 m. The positional accuracy of 2 for most MIPS/IRAC detections provides unambiguous identifications of their optical counterparts. Using spectroscopic redshifts from the Deep Extragalactic Evolutionary Probe survey, we identify 24 m sources at z 1 in the EGS, while the combination of the MIPS/IRAC observations with BVRIJHK ancillary data in the Lockman Hole also shows very clear cases of galaxies with photometric redshifts at 1 z 2.5. The observed 24 m fluxes indicate infrared luminosities greater than 1011 L, while the data at shorter wavelengths reveal rather red and probably massive (M M*) galaxy counterparts. It is the first time that this population of luminous objects is detected up to z 2.5 in the infrared. Our work demonstrates the ability of the MIPS instrument to probe the dusty universe at very high red shift and illustrates how the forthcoming Spitzer deep surveys will offer a unique opportunity to illuminate a dark side of cosmic history not explored by previous infrared experiments.