The Nustar Extragalactic Surveys: Overview and Catalog from the COSMOS Field

Civano, F.; Hickox, R.C.; Puccetti, S.; Comastri, A.; Mullaney, J.R.; Zappacosta, L.; LaMassa, S.M.; Aird, J.; Alexander, D.M.; Ballantyne, D.R.; Bauer, F.E.; Brandt, W.N.; Boggs, S.E.; Christensen, F.E.; Craig, W.W.; Del-Moro, A.; Elvis, M.; Forster, K.; Gandhi, P.; Grefenstette, B.W.; Hailey, C.J.; Harrison, F.A.; Lansbury, G.B.; Luo, B.; Madsen, K.; Saez, C.; Stern, D.; Treister, E.; Urry, M.C.; Wik, D.R.; Zhang, W.

Abstract

To provide the census of the sources contributing to the X-ray background peak above 10 keV, Nuclear Spectroscopic Telescope Array (NuSTAR) is performing extragalactic surveys using a three-tier "wedding cake" approach. We present the NuSTAR survey of the COSMOS field, the medium sensitivity, and medium area tier, covering 1.7 deg2 and overlapping with both Chandra and XMM-Newton data. This survey consists of 121 observations for a total exposure of ~3 Ms. To fully exploit these data, we developed a new detection strategy, carefully tested through extensive simulations. The survey sensitivity at 20% completeness is 5.9, 2.9, and 6.4 × 10−14 $\mathrm{erg}\;{\mathrm{cm}}^{-2}\;{{\rm{s}}}^{-1}$ in the 3–24, 3–8, and 8–24 keV bands, respectively. By combining detections in 3 bands, we have a sample of 91 NuSTAR sources with 1042–1045.5 $\mathrm{erg}\;{{\rm{s}}}^{-1}$ luminosities and redshift z = 0.04–2.5. Thirty-two sources are detected in the 8–24 keV band with fluxes ~100 times fainter than sources detected by Swift-BAT. Of the 91 detections, all but 4 are associated with a Chandra and/or XMM-Newton point-like counterpart. One source is associated with an extended lower energy X-ray source. We present the X-ray (hardness ratio and luminosity) and optical-to-X-ray properties. The observed fraction of candidate Compton-thick active galactic nuclei measured from the hardness ratio is between 13%–20%. We discuss the spectral properties of NuSTAR J100259+0220.6 (ID 330) at z = 0.044, with the highest hardness ratio in the entire sample. The measured column density exceeds 1024 cm−2, implying the source is Compton-thick. This source was not previously recognized as such without the >10 keV data.

Citation

Civano, F., Hickox, R., Puccetti, S., Comastri, A., Mullaney, J., Zappacosta, L., …Zhang, W. (2015). The Nustar Extragalactic Surveys: Overview and Catalog from the COSMOS Field. Astrophysical Journal, 808(2), Article 185. https://doi.org/10.1088/0004-637x/808/2/185

• Journal Article Type: Article
• Online Publication Date: Aug 3, 2015
• Publication Date: Aug 3, 2015
• Deposit Date: May 31, 2016
• Publicly Available Date: Jul 15, 2016
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 808
• Issue: 2
• Article Number: 185
• DOI: https://doi.org/10.1088/0004-637x/808/2/185
• Public URL: https://durham-repository.worktribe.com/output/1379837
• Related Public URLs: http://adsabs.harvard.edu/abs/2015ApJ...808..185C