Extremely Red Objects in the Lockman Hole Academic Article uri icon


  • We investigate extremely red objects (EROs) using near- and mid-infrared observations in five passbands (3.6 to 24 m) obtained from the Spitzer Space Telescope, and deep ground-based R and K imaging. The great sensitivity of the Infrared Array Camera (IRAC) camera allows us to detect 64 EROs (a surface density of 2.90 0.36 arcmin-2; [3.6]AB < 23.7) in only 12 minutes of IRAC exposure time, by means of an R - [3.6] color cut (analogous to the traditional red R - K cut). A pure infrared K - [3.6] red cut detects a somewhat different population and may be more effective at selecting z > 1.3 EROs. We find 17% of all galaxies detected by IRAC at 3.6 or 4.5 m to be EROs. These percentages rise to about 40% at 5.8 m, and about 60% at 8.0 m. We utilize the spectral bump at 1.6 m to divide the EROs into broad redshift slices using only near-infrared colors (2.2/3.6/4.5 m). We conclude that two-thirds of all EROs lie at redshift z > 1.3. Detections at 24 m imply that at least 11% of 0.6 < z < 1.3 EROs and at least 22% of z > 1.3 EROs are dusty star-forming galaxies.

published proceedings

  • The Astrophysical Journal Supplement Series

author list (cited authors)

  • Wilson, G., Huang, J., Prez-Gonzlez, P. G., Egami, E., Ivison, R. J., Rigby, J. R., ... Surace, J.

citation count

  • 20

complete list of authors

  • Wilson, G||Huang, J-S||Pérez-González, PG||Egami, E||Ivison, RJ||Rigby, JR||Alonso-Herrero, A||Barmby, P||Dole, H||Fazio, GG||Le Floc’h, E||Papovich, C||Rigopoulou, D||Bai, L||Engelbracht, CW||Frayer, D||Gordon, KD||Hines, DC||Misselt, KA||Miyazaki, S||Morrison, JE||Rieke, GH||Rieke, MJ||Surace, J

publication date

  • September 2004