Photometric redshifts in the Hawaii-Hubble deep Field-North (H-HDF-N)

G. Yang, Y. Q. Xue, B. Luo, W. N. Brandt, D. M. Alexander, F. E. Bauer, W. Cui, X. Kong, B. D. Lehmer, J. X. Wang, X. B. Wu, F. Yuan, Y. F. Yuan, H. Y. Zhou

Research output: Contribution to journalArticle

4 Scopus citations


We derive photometric redshifts (z phot) for sources in the entire (∼0.4 deg2) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point-spread-function-matched photometry of 15 broad bands from the ultraviolet (U band) to mid-infrared (IRAC 4.5 μm). Our catalog consists of a total of 131,678 sources. We evaluate the z phot quality by comparing z phot with spectroscopic redshifts (z spec) when available, and find a value of normalized median absolute deviation σNMAD = 0.029 and an outlier fraction of 5.5% (outliers are defined as sources having |zphot-zspec |/(1 + zspec) > 0.15) for non-X-ray sources. More specifically, we obtain σNMAD = 0.024 with 2.7% outliers for sources brighter than R = 23 mag, σNMAD = 0.035 with 7.4% outliers for sources fainter than R = 23 mag, σNMAD = 0.026 with 3.9% outliers for sources having z < 1, and σNMAD = 0.034 with 9.0% outliers for sources having z > 1. Our z phot quality shows an overall improvement over an earlier z phot work that focused only on the central H-HDF-N area. We also classify each object as a star or galaxy through template spectral energy distribution fitting and complementary morphological parameterization, resulting in 4959 stars and 126,719 galaxies. Furthermore, we match our catalog with the 2 Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having z spec), we improve their z phot quality by adding three additional active galactic nucleus templates, achieving σNMAD = 0.035 and an outlier fraction of 12.5%. We make our catalog publicly available presenting both photometry and z phot, and provide guidance on how to make use of our catalog.

Original languageEnglish (US)
Article number27
JournalAstrophysical Journal, Supplement Series
Issue number2
StatePublished - Jan 1 2015

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Yang, G., Xue, Y. Q., Luo, B., Brandt, W. N., Alexander, D. M., Bauer, F. E., Cui, W., Kong, X., Lehmer, B. D., Wang, J. X., Wu, X. B., Yuan, F., Yuan, Y. F., & Zhou, H. Y. (2015). Photometric redshifts in the Hawaii-Hubble deep Field-North (H-HDF-N). Astrophysical Journal, Supplement Series, 215(2), [27].