We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.

Durham Research Online
You are in:

# The NuSTAR Extragalactic Surveys : source catalog and the Compton-thick fraction in the UDS field.

Masini, A. and Civano, F. and Comastri, A. and Fornasini, F. and Ballantyne, D. R. and Lansbury, G. B. and Treister, E. and Alexander, D. M. and Boorman, P. G. and Brandt, W. N. and Farrah, D. and Gandhi, P. and Harrison, F. A. and Hickox, R. C. and Kocevski, D. D. and Lanz, L. and Marchesi, S. and Puccetti, S. and Ricci, C. and Saez, C. and Stern, D. and Zappacosta, L. (2018) 'The NuSTAR Extragalactic Surveys : source catalog and the Compton-thick fraction in the UDS field.', Astrophysical journal supplement series., 235 (1). p. 17.

## Abstract

We present the results and the source catalog of the NuSTAR survey in the UKIDSS Ultra Deep Survey (UDS) field, bridging the gap in depth and area between NuSTAR's ECDFS and COSMOS surveys. The survey covers a ~0.6 deg2 area of the field for a total observing time of ~1.75 Ms, to a half-area depth of ~155 ks corrected for vignetting at 3–24 keV, and reaching sensitivity limits at half-area in the full (3–24 keV), soft (3–8 keV), and hard (8–24 keV) bands of 2.2 × 10−14 erg cm−2 s−1, 1.0 × 10−14 erg cm−2 s−1, and 2.7 × 10−14 erg cm−2 s−1, respectively. A total of 67 sources are detected in at least one of the three bands, 56 of which have a robust optical redshift with a median of $\langle z\rangle \sim 1.1$. Through a broadband (0.5–24 keV) spectral analysis of the whole sample combined with the NuSTAR hardness ratios, we compute the observed Compton-thick (CT; N H > 1024 cm−2) fraction. Taking into account the uncertainties on each N H measurement, the final number of CT sources is 6.8 ± 1.2. This corresponds to an observed CT fraction of 11.5% ± 2.0%, providing a robust lower limit to the intrinsic fraction of CT active galactic nuclei and placing constraints on cosmic X-ray background synthesis models.