Initial results from NuSTAR observations of the Norma Arm
Abstract
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 degrees-squared of sky area in the 3--79 keV range with a minimum and maximum raw exposure time 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. 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 magnetar. CXOU J163355.1-473804 features a helium-like iron line at 6.7 keV and is classified as a nearby cataclysmic variable. We close by discussing some challenges inherent in imaging crowded regions with NuSTAR, and how the lessons learned in this pilot study can help scientists who wish to use NuSTAR to observe their favorite targets.
- Publication:
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AAS/High Energy Astrophysics Division #14
- Pub Date:
- August 2014
- Bibcode:
- 2014HEAD...1412218B