PEARLS: NuSTAR and XMM-Newton Extragalactic Survey of the JWST North Ecliptic Pole Time-domain Field III

TL;DR

This paper reports on a multi-year NuSTAR and XMM-Newton survey of the JWST NEP TDF, detecting hundreds of X-ray sources, analyzing their flux distribution, and characterizing obscured and Compton-thick AGN populations.

Contribution

It provides new deep X-ray survey data over a larger area, with updated source counts and obscuration statistics, extending previous work on the NEP field.

Findings

Detected 75 NuSTAR sources and 274 XMM sources at 99% reliability.

Measured a flatter logN-logS slope consistent with Euclidean expectations.

Found approximately 36% of sources are heavily obscured, with a 9% fraction of Compton-thick AGN.

Abstract

The James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-Domain Field (TDF) has been monitored by NuSTAR and XMM-Newton with a regular cadence for five years starting in 2019. The survey has accumulated 3.5Ms of NuSTAR exposure and 228 ks quasi-simultaneous XMM-Newton observations covering 0.31 deg^2. This paper presents the results from the most recent two-years' 2Ms NuSTAR and 166 ks XMM observations in NuSTAR cycles 8 and 9. These observations reached a 20%-area flux of 2.20 x 10^-14 erg cm^-2 s^-1 in the 8-24 keV band. 75 NuSTAR sources and 274 XMM-Newton sources are detected at 99% reliability level. The logN-logS measured in cycles 8+9 are consistent with those measured in the previous cycle 5+6 NuSTAR NEP survey, but in a larger area (0.3 deg^2 compared with 0.19 deg^2). The slope of the cycles 8+9 8-24 keV logN-logS curve is flatter than other works ({\alpha}89 = 1.13 +/- 0.46), but is consistent with the Euclidean value of {\alpha} = 1.50. In addition, we found ~36% of the NuSTAR sources to be heavily obscured (NH >= 10^23 cm^-2). The Compton-thick (NH >= 10^24 cm^-2) (CT-) AGN fraction is 9+18-8% in the NEP-TDF, which is consistent with the measurements in previous surveys.