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Title: NuSTAR Hard X-Ray of the Galactic Center Region. I. Hard X-Ray Morphology and Spectroscopy of the Diffuse Emission

Abstract

Here, 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 Sgr 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,more » 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.« less

Authors:
ORCiD logo [1];  [1]; ORCiD logo [2];  [3];  [4]; ORCiD logo [5];  [6];  [1];  [1]; ORCiD logo [7]; ORCiD logo [8];  [9]; ORCiD logo [10];  [7];  [7];  [1]; ORCiD logo [11];  [12];  [13];  [14] more »;  [13];  [3];  [13];  [11];  [15];  [16];  [1]; ORCiD logo [13];  [13]; ORCiD logo [13];  [17];  [18]; ORCiD logo [17]; ORCiD logo [13]; ORCiD logo [13];  [11];  [19];  [7] « less
  1. Columbia Univ., New York, NY (United States)
  2. Univ. of California, Berkeley, CA (United States); Russian Academy of Sciences, Moscow (Russia)
  3. Harvard Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  4. Max-Planck-Institut f. extraterrestrische Physik, Garching (Germany)
  5. Pontificia Univ. Catolica de Chile, Santiago (Chile); Millennium Institute of Astrophysics, Santiago (Chile); Space Science Institute, Boulder, CO (United States)
  6. Columbia Univ., New York, NY (United States); Harvard College, Haverford, PA (United States)
  7. Univ. of California, Berkeley, CA (United States)
  8. Durham Univ., Durham (United Kingdom)
  9. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  10. Univ. de Toulouse, Toulouse (France); CNRS, Toulouse Cedex (France)
  11. Technical Univ. of Denmark, Lyngby (Denmark)
  12. Univ. of California, Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  13. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  14. ASI Science Data Center, Roma (Italy)
  15. Hiroshima Univ., Hiroshima (Japan)
  16. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  17. ASI Science Data Center, Roma (Italy); INAF - Astronomico di Roma, Monteporzio (Italy)
  18. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  19. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1480407
Report Number(s):
LLNL-JRNL-746966
Journal ID: ISSN 1538-4357; 931727
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 814; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Galaxy: center; radiation mechanisms: non-thermal; X-rays: general; X-rays: ISM

Citation Formats

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, 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, Perri, Matteo, Pivovaroff, Michael J., Puccetti, Simonetta, Rana, Vikram, Stern, Daniel, Westergaard, Niels J., Zhang, William W., and Zoglauer, Andreas. NuSTAR Hard X-Ray of the Galactic Center Region. I. Hard X-Ray Morphology and Spectroscopy of the Diffuse Emission. United States: N. p., 2015. Web. doi:10.1088/0004-637X/814/2/94.
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, 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, Perri, Matteo, Pivovaroff, Michael J., Puccetti, Simonetta, Rana, Vikram, Stern, Daniel, Westergaard, Niels J., Zhang, William W., & Zoglauer, Andreas. NuSTAR Hard X-Ray of the Galactic Center Region. I. Hard X-Ray Morphology and Spectroscopy of the Diffuse Emission. United States. doi:10.1088/0004-637X/814/2/94.
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, 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, Perri, Matteo, Pivovaroff, Michael J., Puccetti, Simonetta, Rana, Vikram, Stern, Daniel, Westergaard, Niels J., Zhang, William W., and Zoglauer, Andreas. Thu . "NuSTAR Hard X-Ray of the Galactic Center Region. I. Hard X-Ray Morphology and Spectroscopy of the Diffuse Emission". United States. doi:10.1088/0004-637X/814/2/94. https://www.osti.gov/servlets/purl/1480407.
@article{osti_1480407,
title = {NuSTAR Hard X-Ray of the Galactic Center Region. I. Hard X-Ray Morphology and Spectroscopy of the Diffuse Emission},
author = {Mori, Kaya and Hailey, Charles J. and Krivonos, Roman and Hong, Jaesub and Ponti, Gabriele and Bauer, Franz and Perez, Kerstin and Nynka, Melania and Zhang, Shuo and Tomsick, John A. and Alexander, David M. and Baganoff, Frederick K. and Barret, Didier and Barrière, Nicolas and Boggs, Steven E. and Canipe, Alicia M. and Christensen, Finn E. and Craig, William W. and Forster, Karl and Giommi, Paolo and Grefenstette, Brian W. and Grindlay, Jonathan E. and Harrison, Fiona A. and Hornstrup, Allan and Kitaguchi, Takao and Koglin, Jason E. and Luu, Vy and Madsen, Kristen K. and Mao, Peter H. and Miyasaka, Hiromasa and Perri, Matteo and Pivovaroff, Michael J. and Puccetti, Simonetta and Rana, Vikram and Stern, Daniel and Westergaard, Niels J. and Zhang, William W. and Zoglauer, Andreas},
abstractNote = {Here, 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 (~1023 cm–2), primary X-ray spectra (power-laws with Γ ~ 2) and set a lower limit of the X-ray luminosity of Sgr A* flare illuminating the Sgr A clouds to LX ≳ 1038 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 MWD ~ 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.},
doi = {10.1088/0004-637X/814/2/94},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 814,
place = {United States},
year = {2015},
month = {11}
}

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