NuSTAR Hard X-Ray Survey of the Galactic Center Region I: Hard X-Ray Morphology and Spectroscopy of the Diffuse Emission
Journal
Date Issued
2015
Author(s)
Mori, Kaya
•
Hailey, Charles J.
•
Krivonos, Roman
•
Hong, Jaesub
•
•
Bauer, Franz
•
Perez, Kerstin
•
Nynka, Melania
•
Zhang, Shuo
•
Tomsick, John A.
•
Alexander, David M.
•
Baganoff, Frederick K.
•
Barret, Didier
•
Barrière, 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.
•
Mao, Peter H.
•
Miyasaka, Hiromasa
•
•
Pivovaroff, Michael J.
•
Puccetti, Simonetta
•
Rana, Vikram
•
Stern, Daniel
•
Westergaard, Niels J.
•
Zhang, William W.
•
Zoglauer, Andreas
Abstract
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 Γ ∼ 1.3-2.3 up 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 Kα 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 (∼10^23 cm^-2), primary X-ray spectra (power-laws with Γ ∼ 2) and set a lower limit of the X-ray luminosity of Sir A* flare illuminating the Sgr A clouds to L_X ≳ 10^38 erg s^-1. Above ∼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 ∼ 0.9 M_☉. 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.
Volume
814
Issue
2
Start page
94
Issn Identifier
0004-637X
Ads BibCode
2015ApJ...814...94M
Rights
open.access
File(s)![Thumbnail Image]()
![Thumbnail Image]()
Loading...
Name
1510.04631.pdf
Description
postprint
Size
4.15 MB
Format
Adobe PDF
Checksum (MD5)
9627aa1151430c3319db1217c7198f3c
Loading...
Name
Mori_2015_ApJ_814_94.pdf
Description
Pdf editoriale
Size
4.31 MB
Format
Adobe PDF
Checksum (MD5)
58ba50383b5d16332cd9f5553a5fadda