The population of BzK-selected ULIRGs at z ∼ 2

E. Daddi, M. Dickinson, R. Chary, A. Pope, G. Morrison, D. M. Alexander, F. E. Bauer, W. N. Brandt, M. Giavalisco, H. Ferguson, K. S. Lee, B. D. Lehmer, C. Papovich, A. Renzini

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We investigate the multiwavelength emission of BzK-selected star-forming galaxies at z ∼ 2 in the Great Observatories Origins Deep Survey (GOODS) North region. Most (82%) of the sources are individually detected at 24 μm in the Spitzer MIPS imaging, and one-fourth (26%) in the VLA radio data. Significant detections of the individually undetected objects are obtained through stacking in the radio, submillimeter, and X-ray domains. The typical star-forming galaxy with stellar mass ∼1011 M at z = 2 is an ultraluminous infrared galaxy (ULIRG), with LIR ∼ (1-2) × 1012 L and star formation rate SFR ≈ 200-300 M yr-1, implying a comoving density of ULIRGs at z = 2 at least 3 orders of magnitude above the local one. SFRs derived from the reddening-corrected UV luminosities agree well, on average, with the longer wavelength estimates. The high 24 μm detection rate suggests a relatively large duty cycle for the BzK star-forming phase, which is consistent with the available independent measurements of the space density of passively evolving galaxies at z > 1.4. If the IMF at z = 2 is similar to the local one, and in particular if it is not top-heavy, this suggests that a substantial fraction of the high-mass tail (≳ 1011 M) of the galaxy stellar mass function was completed by z ≈ 1.4.

Original languageEnglish (US)
Pages (from-to)L13-L16
JournalAstrophysical Journal
Issue number1 II
StatePublished - Sep 20 2005


All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Daddi, E., Dickinson, M., Chary, R., Pope, A., Morrison, G., Alexander, D. M., Bauer, F. E., Brandt, W. N., Giavalisco, M., Ferguson, H., Lee, K. S., Lehmer, B. D., Papovich, C., & Renzini, A. (2005). The population of BzK-selected ULIRGs at z ∼ 2. Astrophysical Journal, 631(1 II), L13-L16.