Photometric Redshifts in the Hawaii-Hubble Deep Field-North (H-HDF-N)

Abstract

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 σ_NMAD = 0.029 and an outlier fraction of 5.5% (outliers are defined as sources having |z_phot - z_spec |/(1 + z_spec ) > 0.15) for non-X-ray sources. More specifically, we obtain σ_NMAD = 0.024 with 2.7% outliers for sources brighter than R = 23 mag, σ_NMAD = 0.035 with 7.4% outliers for sources fainter than R = 23 mag, σ_NMAD = 0.026 with 3.9% outliers for sources having z < 1, and σ_NMAD = 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 σ_NMAD = 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.