The truncated disk from Suzaku data of GX339-4 in the extreme very high state

Manami Tamura, Aya Kubota, Shinya Yamada, Chris Done, Mari Kolehmainen, Yoshihiro Ueda, Shunsuke Torii

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

We report on the geometry of accretion disk and high-energy coronae in the strong Comptonization state (the very high/steep power law/hard intermediate state) based on a Suzaku observation of the famous Galactic black hole GX339-4. These data were taken just before the peak of the 2006-2007 outburst, and the average X-ray luminosity in the 0.7-200keV band is estimated to be 2.9 × 1038 erg s-1 for a distance of 8kpc. We fit the spectrum with both simple (independent disk and corona) and sophisticated (energetically coupled disk and corona) models; all fits imply that the underlying optically thick disk is truncated significantly before the innermost stable circular orbit around the black hole. We show this directly by a comparison with similar broadband data from a disk-dominated spectrum at almost the same luminosity observed by XMM-Newton and RXTE 3days after the Suzaku observation. During the Suzaku observation, the quasi-periodic oscillation (QPO) frequency changes from 4.3Hz to 5.5Hz, while the spectrum softens. The energetically coupled model gives a corresponding 5% ± 8% decrease in the derived inner radius of the disk. While this is not significant, it is consistent with the predicted change in QPO frequency from the Lense-Thirring precession of the hot flow interior to the disk and/or a deformation mode of this flow, as a higher QPO frequency implies a smaller size scale for the corona. This is consistent with the truncated disk extending further inward toward the black hole.

Original languageEnglish
Article number65
JournalAstrophysical Journal
Volume753
Issue number1
DOIs
Publication statusPublished - 2012 Jul 1

Keywords

  • X-rays: stars
  • accretion, accretion disks
  • black hole physics
  • stars: individual (GX 339?4)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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