The NuSTAR extragalactic survey of the James Webb Space Telescope North Ecliptic Pole time-domain field. Issue 4 (6th October 2021)

• Record Type: Journal Article
• Authors: Zhao, X; Civano, F; Fornasini, F M; Alexander, D M; Cappelluti, N; Chen, C T; Cohen, S H; Elvis, M; Gandhi, P; Grogin, N A; Hickox, R C; Jansen, R A; Koekemoer, A; Lanzuisi, G; Maksym, W P; Masini, A; Rosario, D J; Ward, M J; Willmer, C N A; Windhorst, R A
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 508:Issue 4(2021)
• Page Start: 5176
• Page End: 5195
• Publication Date: 2021-10-06
• Subjects: surveys -- galaxies: active -- X-rays: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab2885
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present the NuSTAR extragalactic survey of the James Webb Space Telescope ( JWST ) North Ecliptic Pole (NEP) Time-Domain Field. The survey covers a ∼0.16 deg 2 area with a total exposure of 681 ks acquired in a total of nine observations from three epochs. The survey sensitivities at 20 per cent of the area are 2.39, 1.14, 2.76, 1.52, and 5.20 × 10 −14 erg cm −2 s −1 in the 3–24, 3–8, 8–24, 8–16, and 16–24 keV bands, respectively. The NEP survey is one of the most sensitive extragalactic surveys with NuSTAR so far. A total of 33 sources were detected above 95 per cent reliability in at least one of the five bands. We present the number counts, log N -log S, measured in the hard X-ray 8–24 and 8–16 keV bands, uniquely accessible by NuSTAR down to such faint fluxes. We performed source detection on the XMM – Newton and Chandra observations of the same field to search for soft X-ray counterparts of each NuSTAR detection. The soft band positions were used to identify optical and infrared associations. We present the X-ray properties (hardness ratio and luminosity) and optical-to-X-ray properties of the detected sources. The measured fraction of candidate Compton-thick ( N $\rm _H\ge 10^{24}\, cm^{-2}$ ) active galactic nuclei, derived from the hardness ratio, is between 3 and 27 per cent. As this survey was designed to have variability as its primary focus, we present preliminary results on multiepoch flux variability in the 3–24 keV band.