NuSTAR J033202-2746.8: Direct Constraints on the Compton Reflection in a Heavily Obscured Quasar at Z Approximately Equal to 2

We report Nuclear Spectroscopic Telescope Array (NuSTAR) observations of NuSTAR J033202-2746.8, a heavily obscured, radio-loud quasar detected in the Extended Chandra Deep Field-South, the deepest layer of the NuSTAR extragalactic survey (approximately 400 ks, at its deepest). NuSTAR J033202-2746.8 is reliably detected by NuSTAR only at E greater than 8 keV and has a very flat spectral slope in the NuSTAR energy band (gamma = 0.55(+0.62/0.64); 3-30 keV). Combining the NuSTAR data with extremely deep observations by Chandra and XMM-Newton (4 Ms and 3 Ms, respectively), we constrain the broad-band X-ray spectrum of NuSTAR J033202-2746.8, indicating that this source is a heavily obscured quasar (N(sub H) = 5.6(+0.9/0.8) 10(exp 23) cm(exp 2)) with luminosity L(sub 10-40 keV) approximately equaling 6.4 10(exp 44) erg s(exp 1). Although existing optical and near-infrared (near-IR) data, as well as follow-up spectroscopy with the Keck and VLT telescopes, failed to provide a secure redshift identification for NuSTAR J033202-2746.8, we reliably constrain the redshift z = 2.00 +/- 0.04 from the X-ray spectral features (primarily from the iron K edge). The NuSTAR spectrum shows a significant reflection component (R = 0.55+0.44 0.37), which was not constrained by previous analyses of Chandra and XMM-Newton data alone. The measured reflection fraction is higher than the R approximately 0 typically observed in bright radio-loud quasars such as NuSTAR J033202-2746.8, which has L(sub 1.4 GHz) approximately equal to 10(exp 27) W Hz(exp 1). Constraining the spectral shape of active galactic nuclei (AGNs), including bright quasars, is very important for understanding the AGN population, and can have a strong impact on the modeling of the X-ray background. Our results show the importance of NuSTAR in investigating the broad-band spectral properties of quasars out to high redshift.