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NuSTAR J033202-2746.8: Direct Constraints on the Compton Reflection in a Heavily Obscured Quasar at z ≈ 2

Del Moro, A.; Mullaney, J.R.; Alexander, D.M.; Comastri, A.; Bauer, F.E.; Treister, E.; Stern, D.; Civano, F.; Ranalli, P.; Vignali, C.; Aird, J.A.; Ballantyne, D.R.; Baloković, M.; Boggs, S.E.; Brandt, W.N.; Christensen, F.E.; Craig, W.W.; Gandhi, P.; Gilli, R.; Hailey, C.J.; Harrison, F.A.; Hickox, R.C.; LaMassa, S.M.; Lansbury, G.B.; Luo, B.; Puccetti, S.; Urry, C.M.; Zhang, W.W.

NuSTAR J033202-2746.8: Direct Constraints on the Compton Reflection in a Heavily Obscured Quasar at z ≈ 2 Thumbnail


A. Del Moro

J.R. Mullaney

A. Comastri

F.E. Bauer

E. Treister

D. Stern

F. Civano

P. Ranalli

C. Vignali

J.A. Aird

D.R. Ballantyne

M. Baloković

S.E. Boggs

W.N. Brandt

F.E. Christensen

W.W. Craig

P. Gandhi

R. Gilli

C.J. Hailey

F.A. Harrison

R.C. Hickox

S.M. LaMassa

G.B. Lansbury

B. Luo

S. Puccetti

C.M. Urry

W.W. Zhang


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 (~400 ks, at its deepest). NuSTAR J033202-2746.8 is reliably detected by NuSTAR only at E > 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 ($N_{\rm H}=5.6^{+0.9}_{-0.8}\times 10^{23}$ cm–2) with luminosity L 10-40 keV ≈ 6.4 × 1044 erg s–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 ~ 0 typically observed in bright radio-loud quasars such as NuSTAR J033202-2746.8, which has L 1.4 GHz ≈ 1027 W Hz–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.


Del Moro, A., Mullaney, J., Alexander, D., Comastri, A., Bauer, F., Treister, E., …Zhang, W. (2014). NuSTAR J033202-2746.8: Direct Constraints on the Compton Reflection in a Heavily Obscured Quasar at z ≈ 2. Astrophysical Journal, 786(1),

Journal Article Type Article
Publication Date May 1, 2014
Deposit Date Jun 25, 2014
Publicly Available Date Aug 5, 2014
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 786
Issue 1
Keywords Galaxies: active, infrared: Galaxies, quasars: General, quasars: individual (NuSTAR J033202-2746.8), X-rays
Public URL


Published Journal Article (795 Kb)

Copyright Statement
© 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A.

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