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 deg^2 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 〈z〉 ∼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; NH>10^24 cm^−2) fraction. Taking into account the uncertainties on each NH 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 AGN and placing constraints on cosmic X-ray background synthesis models.
Masini, A., Civano, F., Comastri, A., Fornasini, F., Ballantyne, D.R., Lansbury, G.B., et al. (2018). The NuSTAR Extragalactic Surveys: source catalog and the Compton-thick fraction in the UDS field. ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1, 1-23 [10.3847/1538-4365/aaa83d].
The NuSTAR Extragalactic Surveys: source catalog and the Compton-thick fraction in the UDS field
MASINI, ALBERTO;A. Comastri;
2018
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 deg^2 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 〈z〉 ∼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; NH>10^24 cm^−2) fraction. Taking into account the uncertainties on each NH 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 AGN and placing constraints on cosmic X-ray background synthesis models.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
