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Journal Articles The Astrophysical Journal Year : 2016

NuSTAR Hard X-Ray Survey of the Galactic Center Region. II. X-Ray Point Sources

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Jaesub Hong
  • Function : Author
Kaya Mori
  • Function : Author
Charles J. Hailey
  • Function : Author
Melania Nynka
  • Function : Author
Shuo Zhang
  • Function : Author
Eric Gotthelf
  • Function : Author
Francesca M. Fornasini
  • Function : Author
Roman Krivonos
  • Function : Author
Franz Bauer
Kerstin Perez
  • Function : Author
John A. Tomsick
  • Function : Author
Arash Bodaghee
  • Function : Author
Jeng-Lun Chiu
  • Function : Author
Maïca Clavel
Daniel Stern
  • Function : Author
Jonathan E. Grindlay
  • Function : Author
David M. Alexander
  • Function : Author
Tsuguo Aramaki
  • Function : Author
Frederick K. Baganoff
  • Function : Author
Nicolas Barrière
  • Function : Author
Steven E. Boggs
  • Function : Author
Alicia M. Canipe
  • Function : Author
William W. Craig
  • Function : Author
Meera A. Desai
  • Function : Author
Karl Forster
  • Function : Author
Paolo Giommi
  • Function : Author
Brian W. Grefenstette
  • Function : Author
Fiona A. Harrison
  • Function : Author
Dooran Hong
  • Function : Author
Allan Hornstrup
  • Function : Author
Takao Kitaguchi
  • Function : Author
Jason E. Koglin
  • Function : Author
Kristen K. Madsen
  • Function : Author
Peter H. Mao
  • Function : Author
Hiromasa Miyasaka
  • Function : Author
Matteo Perri
  • Function : Author
Michael J. Pivovaroff
  • Function : Author
Simonetta Puccetti
  • Function : Author
Vikram Rana
  • Function : Author
Niels J. Westergaard
  • Function : Author
William W. Zhang
  • Function : Author
Andreas Zoglauer
  • Function : Author

Abstract

We present the first survey results of hard X-ray point sources in the Galactic Center (GC) region by NuSTAR. We have discovered 70 hard (3-79 keV) X-ray point sources in a 0.6 deg{}2 region around Sgr A* with a total exposure of 1.7 Ms, and 7 sources in the Sgr B2 field with 300 ks. We identify clear Chandra counterparts for 58 NuSTAR sources and assign candidate counterparts for the remaining 19. The NuSTAR survey reaches X-ray luminosities of ∼4× and ∼8 × 10{}32 erg s{}-1 at the GC (8 kpc) in the 3-10 and 10-40 keV bands, respectively. The source list includes three persistent luminous X-ray binaries (XBs) and the likely run-away pulsar called the Cannonball. New source-detection significance maps reveal a cluster of hard (>10 keV) X-ray sources near the Sgr A diffuse complex with no clear soft X-ray counterparts. The severe extinction observed in the Chandra spectra indicates that all the NuSTAR sources are in the central bulge or are of extragalactic origin. Spectral analysis of relatively bright NuSTAR sources suggests that magnetic cataclysmic variables constitute a large fraction (>40%-60%). Both spectral analysis and logN-logS distributions of the NuSTAR sources indicate that the X-ray spectra of the NuSTAR sources should have kT > 20 keV on average for a single temperature thermal plasma model or an average photon index of Γ = 1.5-2 for a power-law model. These findings suggest that the GC X-ray source population may contain a larger fraction of XBs with high plasma temperatures than the field population.

Dates and versions

insu-03669469 , version 1 (16-05-2022)

Identifiers

Cite

Jaesub Hong, Kaya Mori, Charles J. Hailey, Melania Nynka, Shuo Zhang, et al.. NuSTAR Hard X-Ray Survey of the Galactic Center Region. II. X-Ray Point Sources. The Astrophysical Journal, 2016, 825, ⟨10.3847/0004-637X/825/2/132⟩. ⟨insu-03669469⟩
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