The NuSTAR Serendipitous Survey: The 40-month Catalog and the Properties of the Distant High-Energy X-ray Source Population

Lansbury, G.B.; Stern, D.; Aird, J.; Alexander, D.M.; Fuentes, C.; Harrison, F.A.; Treister, E.; Bauer, F.E.; Tomsick, J.A.; Balokovic, M.; Del Moro, A.; Gandhi, P.; Ajello, M.; Annuar, A.; Ballantyne, D.R.; Boggs, S.E.; Brandt, N.; Brightman, M.; Chen, C.J.; Christensen, F.E.; Civano, F.; Comastri, A.; Craig, W.W.; Forster, K.; Grefenstette, B.W.; Hailey, C.J.; Hickox, R.; Jiang, B.; Jun, H.; Koss, M.; Marchesi, S.; Melo, A.D.; Mullaney, J.R.; Noirot, G.; Schulze, S.; Walton, D.J.; Zappacosta, L.; Zhang, W.

Abstract

We present the first full catalog and science results for the NuSTAR serendipitous survey. The catalog incorporates data taken during the first 40 months of NuSTAR operation, which provide ~20Ms of effective exposure time over 331 fields, with an areal coverage of 13 sq deg, and 497 sources detected in total over the 3-24 keV energy range. There are 276 sources with spectroscopic redshifts and classifications, largely resulting from our extensive campaign of ground-based spectroscopic followup. We characterize the overall sample in terms of the X-ray, optical, and infrared source properties. The sample is primarily comprised of active galactic nuclei (AGNs), detected over a large range in redshift from z = 0.002 - 3.4 (median of = 0.56), but also includes 16 spectroscopically confirmed Galactic sources. There is a large range in X-ray flux, from log( f_3-24keV / erg s^-1 cm^-2 ) ~ -14 to -11, and in rest-frame 10-40 keV luminosity, from log( L_10-40keV / erg s^-1 ) ~ 39 to 46, with a median of 44.1. Approximately 79% of the NuSTAR sources have lower energy (<10 keV) X-ray counterparts from XMM-Newton, Chandra, and Swift/XRT. The mid-infrared (MIR) analysis, using WISE all-sky survey data, shows that MIR AGN color selections miss a large fraction of the NuSTAR-selected AGN population, from ~15% at the highest luminosities (Lx > 10^44 erg s^-1) to ~80% at the lowest luminosities (Lx < 10^43 erg s^-1). Our optical spectroscopic analysis finds that the observed fraction of optically obscured AGNs (i.e., the Type 2 fraction) is F_Type2 = 53(+14-15)%, for a well-defined subset of the 8-24 keV selected sample. This is higher, albeit at a low significance level, than the Type 2 fraction measured for redshift- and luminosity-matched AGNs selected by <10 keV X-ray missions.

Citation

Lansbury, G., Stern, D., Aird, J., Alexander, D., Fuentes, C., Harrison, F., …Zhang, W. (2017). The NuSTAR Serendipitous Survey: The 40-month Catalog and the Properties of the Distant High-Energy X-ray Source Population. Astrophysical Journal, 836(1), Article 99. https://doi.org/10.3847/1538-4357/836/1/99

• Journal Article Type: Article
• Acceptance Date: Dec 7, 2016
• Online Publication Date: Feb 10, 2017
• Publication Date: Feb 10, 2017
• Deposit Date: Jan 20, 2017
• Publicly Available Date: Feb 7, 2017
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 836
• Issue: 1
• Article Number: 99
• DOI: https://doi.org/10.3847/1538-4357/836/1/99
• Public URL: https://durham-repository.worktribe.com/output/1365752
• Related Public URLs: https://arxiv.org/abs/1612.06389