NuSTAR HARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. I. HARD X-RAY MORPHOLOGY AND SPECTROSCOPY OF THE DIFFUSE EMISSION

作者：Mori Kaya; Hailey Charles J; Krivonos Roman; Hong Jaesub; Ponti Gabriele; Bauer Franz; Perez Kerstin; Nynka Melania; Zhang Shuo; Tomsick John A; Alexander David M; Baganoff Frederick K; Barret Didier; Barriere Nicolas; Boggs Steven E; Canipe Alicia M; Christensen Finn E; Craig William W; Forster Karl; Giommi Paolo; Grefenstette Brian W; Grindlay Jonathan E; Harrison Fiona A; Hornstrup Allan; Kitaguchi Takao; Koglin Jason E; Luu Vy; Madsen Kristen K

来源：Astrophysical Journal, 2015, 814(2): 94.

DOI：10.1088/0004-637X/814/2/94

• Galaxy: center
• radiation mechanisms: non-thermal
• X-rays: general
• X-rays: ISM

We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456-2901 into non-thermal X-ray filaments, molecular clouds, point sources, and a previously unknown central component of hard X-ray emission (CHXE). NuSTAR detects four non-thermal X-ray filaments, extending the detection of their power-law spectra with Gamma similar to 1.3-2.3 up to similar to 50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4 keV Fe K alpha fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broadband X-ray spectral analysis with a Monte-Carlo based X-ray reflection model self-consistently determined their intrinsic column density (similar to 10(23) cm(-2)), primary X-ray spectra (power-laws with Gamma similar to 2) and set a lower limit of the X-ray luminosity of Sgr A* flare illuminating the Sgr A clouds to L-X >= 10(38) erg s(-1). Above similar to 20 keV, hard X-ray emission in the central 10 pc region around Sgr A* consists of the candidate PWN G359.95-0.04 and the CHXE, possibly resulting from an unresolved population of massive CVs with white dwarf masses M-WD similar to 0.9M(circle dot). Spectral energy distribution analysis suggests that G359.95-0.04 is likely the hard X-ray counterpart of the ultra-high gamma-ray source HESS J1745-290, strongly favoring a leptonic origin of the GC TeV emission.

• 出版日期2015-12-1