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arXiv · astro-ph/9907216

The Surface Density of Extremely Red Objects

D. Thompson·S. V. W. Beckwith·R. Fockenbrock·J. Fried·H. Hippelein·J. -S. Huang·B. von Kuhlmann·Ch. Leinert·K. Meisenheimer·S. Phleps·H. -J. Röser·E. Thommes·C. Wolf
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Abstract

We present initial results from a field survey for extremely red objects (EROs, defined here as (R-K') >= 6 mag) covering 154 square arcminutes of sky, from the first of 7 deep, wide-field K' images obtained as part of the Calar Alto Deep Imaging Survey (CADIS). The 5-sigma point source detection limits are K'=20.5 and R=25.0, while extended-source limits are up to 0.5-0.75 mag brighter. We identify a total of 8 bright EROs with K' =< 19.0. Six of these bright EROs are resolved and are likely to be galaxies, while the remaining 2 are unresolved, with colors consistent with their being low-mass galactic stars. We derive a surface density for the 6 bright, extragalactic EROs of 0.039 +/- 0.016 per sq. arcmin, higher by a factor of 4 than previous values. We estimate that the volume density of bright EROs to be as high as that of nearby Seyfert galaxies.

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D. Thompson, S. V. W. Beckwith, R. Fockenbrock, J. Fried, H. Hippelein, J. -S. Huang, B. von Kuhlmann, Ch. Leinert, K. Meisenheimer, S. Phleps, H. -J. Röser, E. Thommes, C. Wolf. 1999-07-19. The Surface Density of Extremely Red Objects. https://doi.org/10.1086/307708

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