Spectral and timing properties of the black hole x-ray binary h1743-322 in the low/hard state studied with Suzaku

M. Shidatsu, Y. Ueda, S. Yamada, C. Done, T. Hori, K. Yamaoka, A. Kubota, T. Nagayama, Y. Moritani

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29 Citations (Scopus)


We report on the results from Suzaku observations of the Galactic black hole X-ray binary H1743-322 in the low/hard state during its outburst in 2012 October. We appropriately take into account the effects of dust scattering to accurately analyze the X-ray spectra. The time-averaged spectra in the 1-200 keV band are dominated by a hard power-law component of a photon index of ≈1.6 with a high-energy cutoff at ≈60 keV, which is well described with the Comptonization of the disk emission by the hot corona. We estimate the inner disk radius from the multi-color disk component, and find that it is 1.3-2.3 times larger than the radius in the high/soft state. This suggests that the standard disk was not extended to the innermost stable circular orbit. A reflection component from the disk is detected with R = Ω/2π ≈ 0.6 (Ω is the solid angle). We also successfully estimate the stable disk component independent of the time-averaged spectral modeling by analyzing short-term spectral variability on a ∼1 s timescale. A weak low-frequency quasi-periodic oscillation at 0.1-0.2 Hz is detected, whose frequency is found to correlate with the X-ray luminosity and photon index. This result may be explained by the evolution of the disk truncation radius.

Original languageEnglish
Article number100
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2014 Jul 10


  • X-rays: binaries
  • X-rays: individual (H1743-322)
  • accretion, accretion disks
  • black hole physics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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