The pattern of correlated X-ray timing and spectral behavior in GRS 1915+105

Xingming Chen*, Jean H. Swank, Ronald E. Taam

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

From data obtained from the proportional counter array in the 2-11 keV and 11-30.5 keV energy ranges, GRS 1915+105 is seen during Rossi X-Ray Timing Explorer observations between 1996 May and October on two separate branches in a hardness-intensity diagram. On the hard branch, GRS 1915+105 exhibits narrow quasi-periodic oscillations (QPOs) ranging from 0.5 to 6 Hz with Av/v ∼ 0.2. The QPOs are observed over intensities ranging from about 6000 to 20,000 counts s-1 in the 2-12.5 keV energy band, indicating a strong dependence on source intensity. Strong harmonics are seen, especially at lower frequencies. As the QPO frequency increases, the harmonic feature weakens and disappears. On the soft branch, narrow QPOs are absent and the low-frequency component of the power density spectrum is approximated by a power law, with index of about -1.25 for low count rates and -1.5 for high count rates (≳18,000 counts s-1). Occasionally, a broad, peaked feature in the 1-6 Hz frequency range is also observed on this branch. The source was probably in a very high state similar to those of other black hole candidates. Thermal-viscous instabilities in accretion disk models do not predict the correlation of the narrow QPO frequency and luminosity unless the fraction of luminosity from the disk decreases with the total luminosity.

Original languageEnglish (US)
Pages (from-to)L41-L44
JournalAstrophysical Journal
Volume477
Issue number1 PART II
DOIs
StatePublished - 1997

Keywords

  • Accretion, accretion disks
  • Binaries: close
  • X-rays: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'The pattern of correlated X-ray timing and spectral behavior in GRS 1915+105'. Together they form a unique fingerprint.

Cite this