The NuSTAR Extragalactic Surveys: Initial Results and Catalog from the Extended Chandra Deep Field South

TL;DR

This paper reports initial results and a catalog from the NuSTAR survey of the Extended Chandra Deep Field South, detecting 49 significant X-ray sources, including one potentially new source, and analyzing their properties across multiple energy bands.

Contribution

It provides the deepest NuSTAR extragalactic survey data for ECDFS, including a catalog of 49 significant sources and analysis of their spectral and redshift properties, with the discovery of a potential new X-ray source.

Findings

Detected 49 significant sources in the ECDFS with NuSTAR.

Sources span redshifts 0.21-2.7 and luminosities 0.7-300 x 10^43 erg/s.

Identified one new potential X-ray source without Chandra or XMM counterparts.

Abstract

We present initial results and the source catalog from the NuSTAR survey of the Extended Chandra Deep Field South (hereafter, ECDFS) - currently the deepest contiguous component of the NuSTAR extragalactic survey program. The survey covers the full ~30 arcmin x 30 arcmin area of this field to a maximum depth of ~360 ks (~220 ks when corrected for vignetting at 3-24 keV), reaching sensitivity limits of ~1.3 x 10^-14 erg/cm2/s (3-8 keV), ~3.4 x 10^-14 erg/cm2/s (8-24 keV) and ~3.0 x 10^-14 erg/cm2/s (3-24 keV). Fifty four (54) sources are detected over the full field, although five of these are found to lie below our significance threshold once contaminating flux from neighboring (i.e., blended) sources is taken into account. Of the remaining 49 that are significant, 19 are detected in the 8-24 keV band. The 8-24 keV to 3-8 keV band ratios of the twelve sources that are detected in both bands span the range 0.39-1.7, corresponding to a photon index range of Gamma ~ 0.5-2.3, with a median photon index of 1.70 +/- 0.52. The redshifts of the 49 sources in our main sample span the range z = 0.21-2.7, and their rest-frame 10-40 keV luminosities (derived from the observed 8-24 keV fluxes) span the range L(10-40 keV) ~ (0.7-300) x 10^43 erg/s, sampling below the "knee" of the X-ray luminosity function out to z ~ 0.8-1. Finally, we identify one NuSTAR source that has neither a Chandra nor an XMM-Newton counterpart, but that shows evidence of nuclear activity at infrared wavelengths, and thus may represent a genuine, new X-ray source detected by NuSTAR in the ECDFS.