Chandra survey in the AKARI North Ecliptic Pole Deep Field – I. X-ray data, point-like source catalogue, sensitivity maps, and number counts

Abstract

We present data products from the 300 ks Chandra survey in the AKARI North Ecliptic Pole (NEP) deep field. This field has a unique set of 9-band infrared photometry covering 2-24 µm from the AKARI Infrared Camera, including mid-infrared (MIR) bands not covered by Spitzer. The survey is one of the deepest ever achieved at ∼15 µm, and is by far the widest among those with similar depths in the MIR. This makes this field unique for the MIR-selection of AGN at z ∼ 1.We design a source detection procedure, which performs joint Maximum Likelihood PSF fits on all of our 15 mosaicked Chandra pointings covering an area of 0.34 deg 2 . The procedure has been highly optimized and tested by simulations. We provide a point source catalog with photometry and Bayesian-based 90 per cent confidence upper limits in the 0.5-7, 0.5-2, 2-7, 2-4, and 4-7 keV bands. The catalog contains 457 X-ray sources and the spurious fraction is estimated to be ∼1.7 per cent. Sensitivity and 90 per cent confidence upper flux limits maps in all bands are provided as well.We search for optical MIR counterparts in the central 0.25 deg 2 , where deep Subaru Suprime-Cam multiband images exist. Among the 377 X-ray sources detected there, ∼80 per cent have optical counterparts and ∼60 per cent also have AKARI mid-IR counterparts. We cross-match our X-ray sources with MIR-selected AGN from Hanami et al. Around 30 per cent of all AGN that have MID-IR SEDs purely explainable by AGN activity are strong Compton-thick AGN candidates.

The Chandra Cosmos Legacy Survey: Overview and Point Source Catalog

“…CMLDetect has been adapted to run on Chandra data by replacing the XMM-Newton PSF library with the Chandra one (see Krumpe et al 2015 for another application of CMLDetect). Moreover, this new tool can also work with different PSFs simultaneously.…”

Overview of North Ecliptic Pole Deep Multi-Wavelength Survey (Nep-Deep)

“…Hanami et al (2012) showed that the rest-frame 8 µm and 5 µm luminosities are good tracers of star-forming and AGN activities from their Polycyclic Aromatic Hydrocarbons (PAH) and dusty tori emissions, respectively. As for the AGN dominated MIR-selected sources (inferred from their MIR SEDs), Krumpe et al (2014) found a high (∼ 40%) X-ray detection rate, while sources without any sign of AGN activity in their MIR SEDs have a very low X-ray detection rate of 3%. They also concluded that roughly 30% of IR-selected AGN are strong Comptonthick AGN candidates; this is about to be verified by rest-frame X-ray stacking (Miyaji et al in prep.).…”

“…As for the optical-NIR data, new band-merged catalogue (u * , g , r , i , z , Y , J, K s ) was generated from (Oi et al, 2014). The 300 ks Chandra X-ray image data are also published in Krumpe et al (2014).…”

Spitzer Observations of the North Ecliptic Pole

“…The NEP (centered at R.A. = 18 h 00 m 00 s , decl.= 66 d 33 m 38 552) is the natural extragalactic deep field and has one of the deepest observations by several space observatories, including Planck and AKARI (Serjeant et al 2012). Furthermore, it has extensive observations from the X-ray to the millimeter (Kollgaard et al 1994;Gioia et al 2003;Lee et al 2007;Jeon et al 2010Jeon et al , 2014Krumpe et al 2015), with additional observations by WISE (Jarrett et al 2011). The field was specifically chosen to match the observations by the Cosmic Infrared Background Experiment (CIBER; Bock et al 2013;Zemcov et al 2014 as per msp) to study the extragalactic background light fluctuation (Cooray et al 2004(Cooray et al , 2012aMatsumoto et al 2005;Zemcov et al 2014;Matsuura et al 2017).…”

“…The Spitzer infrared observations in the NEP could additionally be utilized (in conjunction with the already existing X-ray observations; Krumpe et al 2015) to identify AGNs (Stern et al 2005). The NEP imaging data are particularly important for studies of diffuse light background fluctuations arising from individually undetected sources directly probing early star formation (Cooray et al 2004(Cooray et al , 2012aZemcov et al 2014).…”