CANDELS/GOODS-S, CDFS, ECDFS: Photometric Redshifts For Normal and for X-Ray-Detected Galaxies

TL;DR

This paper provides accurate photometric redshifts for sources in the ECDFS, utilizing advanced data and methods, including intermediate-band photometry and hybrid templates, improving the reliability of galaxy and X-ray source distance estimates.

Contribution

Introduces a new approach combining intermediate-band photometry and hybrid templates for improved photometric redshift estimation in deep field surveys.

Findings

Photometric redshift accuracy for normal galaxies is 0.010.

Photometric redshift accuracy for X-ray sources is 0.014.

Reliable counterparts identified for 96% of X-ray sources.

Abstract

We present photometric redshifts and associated probability distributions for all detected sources in the Extended Chandra Deep Field South (ECDFS). The work makes use of the most up-to-date data from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS) and the Taiwan ECDFS Near-Infrared Survey (TENIS) in addition to other data. We also revisit multi-wavelength counterparts for published X-ray sources from the 4Ms-CDFS and 250ks-ECDFS surveys, finding reliable counterparts for 1207 out of 1259 sources ($\sim 96\%$). Data used for photometric redshifts include intermediate-band photometry deblended using the TFIT method, which is used for the first time in this work. Photometric redshifts for X-ray source counterparts are based on a new library of AGN/galaxy hybrid templates appropriate for the faint X-ray population in the CDFS. Photometric redshift accuracy for normal galaxies is 0.010 and for X-ray sources is 0.014, and outlier fractions are $4\%$ and $5.4\%$ respectively. The results within the CANDELS coverage area are even better as demonstrated both by spectroscopic comparison and by galaxy-pair statistics. Intermediate-band photometry, even if shallow, is valuable when combined with deep broad-band photometry. For best accuracy, templates must include emission lines.