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Extended hard-X-ray emission in the inner few parsecs of the Galaxy

Perez, Kerstin M. and Hailey, Charles J. and Bauer, Franz E. and Krivonos, Roman A. and Mori, Kaya and Baganoff, Frederick K. and Boggs, Steven E. and Christensen, Finn E. and Craig, William W. and Grefenstette, Brian W. and Grindlay, Jonathan E. and Harrison, Fiona A. and Hong, Jaesub and Madsen, Kristin K. and Nynka, Melania and Stern, Daniel and Tomsick, John A. and Wik, Daniel R. and Zhang, Shuo and Zhang, William W. and Zoglauer, Andreas (2015) Extended hard-X-ray emission in the inner few parsecs of the Galaxy. Nature, 520 (7549). pp. 646-649. ISSN 0028-0836. http://resolver.caltech.edu/CaltechAUTHORS:20150209-221241720

[img] MS PowerPoint (Figure 1 - The 20–40 keV image of the inner 5′ × 5′ (12 pc × 12 pc) of the Galaxy) - Supplemental Material
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[img] MS PowerPoint (Figure 2 - Profiles of the 20–40 keV data and spatial model along Galactic longitude and latitude.) - Supplemental Material
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[img] MS PowerPoint (Figure 3 - Unfolded broadband X-ray spectrum of the southwest region) - Supplemental Material
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[img] Image (JPEG) (Extended Data Figure 1: The best-fit 20–40 keV spatial model and residual image) - Supplemental Material
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[img] Image (JPEG) (Extended Data Figure 2: Profiles of the 20–40 keV data and exponential spatial model along Galactic longitude and latitude) - Supplemental Material
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[img] Image (JPEG) (Extended Data Figure 3: Regions used for extraction of background spectra for NuSTAR observations 30001002001 (red), 30001002003 (white), and 30001002004 (green)) - Supplemental Material
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[img] Image (JPEG) (Extended Data Figure 4: Unfolded 2–40 keV energy spectrum from the southwest region indicated in Fig. 1) - Supplemental Material
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[img] Image (JPEG) (Extended Data Figure 5: Unfolded 2–40 keV energy spectrum from the northeast region indicated in Fig. 1) - Supplemental Material
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[img] Image (JPEG) (Extended Data Figure 6: Unfolded 2–40 keV energy spectrum from the northeast region indicated in Fig. 1) - Supplemental Material
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[img] Image (JPEG) (Extended Data Table 1: Best fit 2D Gaussian Models) - Supplemental Material
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[img] Image (JPEG) (Extended Data Table 2: Fits with hard emission modelled as power law) - Supplemental Material
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[img] Image (JPEG) (Extended Data Table 3: Fits with hard emission modelled as thermal bremsstrahlung) - Supplemental Material
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Abstract

The Galactic Centre hosts a puzzling stellar population in its inner few parsecs, with a high abundance of surprisingly young, relatively massive stars bound within the deep potential well of the central supermassive black hole, Sagittarius A*. Previous studies suggest that the population of objects emitting soft X-rays (less than 10 kiloelectronvolts) within the surrounding hundreds of parsecs, as well as the population responsible for unresolved X-ray emission extending along the Galactic plane, is dominated by accreting white dwarf systems. Observations of diffuse hard X-ray (more than 10 kiloelectronvolts) emission in the inner 10 parsecs, however, have been hampered by the limited spatial resolution of previous instruments. Here we report the presence of a distinct hard-X-ray component within the central 4 X 8 parsecs, as revealed by subarcminute-resolution images in the 20–40 kiloelectronvolt range. This emission is more sharply peaked towards the Galactic Centre than is the surface brightness of the soft-X-ray population. This could indicate a significantly more massive population of accreting white dwarfs, large populations of lowmass X-ray binaries or millisecond pulsars, or particle outflows interacting with the surrounding radiation field, dense molecular material or magnetic fields. However, all these interpretations pose significant challenges to our understanding of stellar evolution, binary formation, and cosmic-ray production in the Galactic Centre.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1038/nature14353DOIArticle
http://www.nature.com/nature/journal/v520/n7549/full/nature14353.htmlPublisherArticle
http://rdcu.be/cHt1PublisherFree ReadCube access
ORCID:
AuthorORCID
Bauer, Franz E.0000-0002-8686-8737
Krivonos, Roman A.0000-0003-2737-5673
Mori, Kaya0000-0002-9709-5389
Boggs, Steven E.0000-0001-9567-4224
Harrison, Fiona A.0000-0003-2992-8024
Madsen, Kristin K.0000-0003-1252-4891
Stern, Daniel0000-0003-2686-9241
Additional Information:© 2015 Macmillan Publishers Limited. Received 15 December 2014 Accepted 24 February 2015, Published 30 April 2015. This work was supported by NASA contract no. NNG08FD60C, and 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 NASA. 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 thank A. Canipe, J. Dodaro, D. Hong and T. V. T. Luu for assistance with data preparation and analysis. F.E.B. acknowledges support from Basal-CATA PFB-06/2007, CONICYT-Chile (FONDECYT 1141218 and EMBIGGEN Anillo ACT1101), and Project IC120009 ‘‘Millennium Institute of Astrophysics (MAS)’’ funded by the Iniciativa Cientı´fica Milenio del Ministerio de Economı´a, Fomento y Turismo.
Group:NuSTAR, Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
NASANNG08FD60C
Basal-CATAPFB-06/2007
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1141218
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)EMBIGGEN Anillo ACT1101
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
Record Number:CaltechAUTHORS:20150209-221241720
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150209-221241720
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54617
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:01 May 2015 01:49
Last Modified:29 Sep 2017 21:17

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