Surface density of extremely red objects with R - J ≥ 5
Geneva Observatory, 51 Ch. des Maillettes, Sauverny 1290, Switzerland e-mail: Angela.Hempel@obs.unige.ch
2 Max Planck Institute for Astronomy (MPIA), Königstuhl 17, 69117 Heidelberg, Germany e-mail: firstname.lastname@example.org
3 The Palomar Observatory, California Institute of Technology, Pasadena, CA 91125, USA e-mail: email@example.com
Accepted: 5 April 2005
We present the results of a wide-field survey for extremely red objects (EROs), based on J and R band imaging. The survey covers 2.89 deg2, consisting of 50 single fields, each approximately 210 arcmin2 in size. This survey provides a sample of 60 extended objects with a colour of and J band magnitudes more than 10σ above background (). Thirty five of these objects have been detected in both J and R-band. We derive a surface density for such EROs of arcmin-2, which is about seven times lower than for galaxies with . Stellar population models suggest that these EROs are massive galaxies with an old stellar population in a redshift range of . For this scenario, we estimate the co-moving volume density to be ( Mpc-3.
Key words: Galaxy: evolution / galaxies: high-redshift / galaxies: elliptical and lenticular, cD
© ESO, 2005