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Paper: The ISO–2MASS AGN Survey
Volume: 381, The Second Annual Spitzer Science Center Conference: Infrared Diagnostics of Galaxy Evolution
Page: 422
Authors: Leipski, C.; Haas, M.; Meusinger, H.; Siebenmorgen, R.
Abstract: We combined the ISOCAM Parallel Mode Survey at 6.7 μm (LW2 filter) with the Two Micron All Sky Survey in order to obtain a powerful tool to search for AGN independent of dust extinction. Using moderate color criteria H−K > 0.5 and K−LW2 > 2.7 we have selected a sample of 77 AGN candidates in an effective area of ∼10 square degrees. By means of optical spectroscopy we find 24 (∼ 30%) type–1 QSOs at redshifts 0.1 < z < 2.3; nine of them have z > 0.8. About one third of the ISO–2MASS QSOs show so red optical colors, that they are missed in optical and UV AGN surveys like SDSS, 2DF, or HES. With a surface density of about 2 deg−2 down to R < 18 mag, the ISO– 2MASS QSOs outnumber the 1.35 deg−2 of the SDSS quasar survey by 50%. Since only two of the ISO–2MASS QSOs have also J − K > 2, the inclusion of the ISO mid–infrared photometry significantly extends the capabilities of the pure 2MASS red AGN survey. We suggest that the newly found red AGN resemble young members of the quasar population, and that quasars spend much of their lifetime in a dust enshrouded phase. Subsequent MIR spectroscopy with Spitzer revealed that the emission–line galaxies found by the survey show unusual properties. These sources may represent very dusty but only moderately star forming objects that are frequent in the nearby universe.
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