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The NuSTAR Hard X-Ray Survey of the Norma Arm Region

Fornasini, Francesca M. and Forster, Karl and Grefenstette, Brian W. and Harrison, Fiona A. and Madsen, Kristin K. and Mao, Peter H. and Miyasaka, Hiromasa and Rana, Vikram (2017) The NuSTAR Hard X-Ray Survey of the Norma Arm Region. Astrophysical Journal Supplement Series, 229 (2). Art. No. 33. ISSN 0067-0049.

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We present a catalog of hard X-ray sources in a square-degree region surveyed by the Nuclear Spectroscopic Telescope Array (NuSTAR) in the direction of the Norma spiral arm. This survey has a total exposure time of 1.7 Ms, and the typical and maximum exposure depths are 50 ks and 1 Ms, respectively. In the area of deepest coverage, sensitivity limits of 5 × 10^(−14) and 4 × 10^(−14) erg s^(−1) cm^(−2) in the 3–10 and 10–20 keV bands, respectively, are reached. Twenty-eight sources are firmly detected, and 10 are detected with low significance; 8 of the 38 sources are expected to be active galactic nuclei. The three brightest sources were previously identified as a low-mass X-ray binary, high-mass X-ray binary, and pulsar wind nebula. Based on their X-ray properties and multiwavelength counterparts, we identify the likely nature of the other sources as two colliding wind binaries, three pulsar wind nebulae, a black hole binary, and a plurality of cataclysmic variables (CVs). The CV candidates in the Norma region have plasma temperatures of ≈10–20 keV, consistent with the Galactic ridge X-ray emission spectrum but lower than the temperatures of CVs near the Galactic center. This temperature difference may indicate that the Norma region has a lower fraction of intermediate polars relative to other types of CVs compared to the Galactic center. The NuSTAR logN–logS distribution in the 10–20 keV band is consistent with the distribution measured by Chandra at 2–10 keV if the average source spectrum is assumed to be a thermal model with kT ≈ 15 keV, as observed for the CV candidates.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Forster, Karl0000-0001-5800-5531
Grefenstette, Brian W.0000-0002-1984-2932
Harrison, Fiona A.0000-0003-2992-8024
Madsen, Kristin K.0000-0003-1252-4891
Miyasaka, Hiromasa0000-0002-8074-4186
Rana, Vikram0000-0003-1703-8796
Additional Information:© 2017 American Astronomical Society. Received 2016 October 12. Accepted 2017 February 19. Published 2017 April 6. We thank the referee for feedback that helped improve the clarity of the work presented in this paper. This work made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR operations, software, and calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS), jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). We also made use of observations taken by the Chandra X-ray Observatory and of software provided by the Chandra X-ray Center (CXC) in the application packages CIAO and Sherpa. This work also made use of data products from observations made with ESO telescopes at the La Silla or Paranal Observatories under ESO program ID 179.B-2002. In addition, F.M.F. acknowledges support from the National Science Foundation Graduate Research Fellowship and thanks G. K. Keating for helpful conversations on some of the statistical measures and figures in the paper. JAT acknowledges support from Chandra grants GO4-15138X and GO5-16152X. FEB acknowledges support from CONICYT-Chile grants Basal-CATA PFB-06/2007, FONDECYT Regular 1141218, "EMBIGGEN" Anillo ACT1101, and the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to the Millennium Institute of Astrophysics (MAS). JCS acknowledges support from FONDECYT 3140310. RK acknowledges support from the Russian Science Foundation (grant 14-12-01315). DB thanks the French Space Agency (CNES) for financial support.
Group:NuSTAR, Astronomy Department
Funding AgencyGrant Number
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1141218
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)ACT1101
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
Millennium Institute of Astrophysics (MAS)UNSPECIFIED
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3140310
Russian Science Foundation14-12-01315
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20170407-140117671
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Official Citation:Francesca M. Fornasini et al 2017 ApJS 229 33
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75859
Deposited By: Ruth Sustaita
Deposited On:07 Apr 2017 22:19
Last Modified:04 Dec 2019 23:47

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