Initial results from NuSTAR observations of the Norma arm

Arash Bodaghee, John A. Tomsick, Roman Krivonos, Daniel Stern, Franz E. Bauer, Francesca M. Fornasini, Nicolas Barriere, Steven E. Boggs, Finn Erland Christensen, William W. Craig, Eric V. Gotthelf, Charles J. Hailey, Fiona A. Harrison, Jaesub Hong, Kaya Mori, William W. Zhang

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Results are presented for an initial survey of the Norma Arm gathered with the focusing hard X-Ray Telescope NuSTAR. The survey covers 0.2 deg(2) of sky area in the 3-79 keV range with a minimum and maximum raw depth of 15 ks and 135 ks, respectively. Besides a bright black-hole X-ray binary in outburst (4U 1630-47) and a new X-ray transient (NuSTAR J163433-473841), NuSTAR locates three sources from the Chandra survey of this region whose spectra are extended above 10 keV for the first time: CXOU J163329.5-473332, CXOU J163350.9-474638, and CXOU J163355.1-473804. Imaging, timing, and spectral data from a broad X-ray range (0.3-79 keV) are analyzed and interpreted with the aim of classifying these objects. CXOU J163329.5-473332 is either a cataclysmic variable or a faint low-mass X-ray binary. CXOU J163350.9-474638 varies in intensity on year-long timescales, and with no multi-wavelength counterpart, it could be a distant X-ray binary or possibly a magnetar. CXOU J163355.1-473804 features a helium-like iron line at 6.7 keV and is classified as a nearby cataclysmic variable. Additional surveys are planned for the Norma Arm and Galactic Center, and those NuSTAR observations will benefit from the lessons learned during this pilot study.
Original languageEnglish
Article number10
JournalAstrophysical Journal
Issue number68
Publication statusPublished - 2014


  • binaries: general
  • novae, cataclysmic variables
  • stars: neutron
  • X-rays: binaries

Cite this

Bodaghee, A., Tomsick, J. A., Krivonos, R., Stern, D., Bauer, F. E., Fornasini, F. M., Barriere, N., Boggs, S. E., Christensen, F. E., Craig, W. W., Gotthelf, E. V., Hailey, C. J., Harrison, F. A., Hong, J., Mori, K., & Zhang, W. W. (2014). Initial results from NuSTAR observations of the Norma arm. Astrophysical Journal, 791(68), [10].