A compton upscattering model for soft lags in the lower kilohertz quasi-periodic oscillation in 4u 1608-52

Hyong C. Lee*, R. Misra, Ronald E. Taam

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

An empirical Compton upscattering model is described that reproduces both the fractional amplitude (rms) versus energy and the soft time lags in the ≈830 Hz quasi-periodic oscillation (QPO) observed in 4U 1608-52 on 1996 March 3. A combination of two coherent variations in the coronal and soft photon temperatures (with their relative contributions determined by enforcing energy conservation) gives rise to the QPO's energy-dependent characteristics. All input parameters to the model, save a characteristic plasma size and the fraction of Comptonized photons impinging on the soft photon source, are derived from the time-averaged photon energy spectrum of the same observation. Fits to the fractional rms and phase lag data for this kilohertz QPO imply that the spatial extent of the plasma is in the range from ∼4 to 15 km.

Original languageEnglish (US)
Pages (from-to)L229-L232
JournalAstrophysical Journal
Volume549
Issue number2 PART 2
DOIs
StatePublished - Mar 10 2001

Keywords

  • Accretion, accretion disks
  • Radiation mechanisms: thermal
  • Stars: neutron
  • X-rays: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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