A Variable 0.58-2.44 HZ Quasi-periodic Oscillation in the Eclipsing and Dipping Low-Mass X-Ray Binary EXO 0748-676

J Homan, PG Jonker, Rudy Adam Dirk Wijnands, M van der Klis, J van Paradijs

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

We report the discovery of a quasi-periodic oscillation (QPO) in data obtained with the Rossi X-Ray Timing Explorer of the dipping and eclipsing low-mass X-ray binary EXO 0748-676. The QPO had a frequency between 0.58 and 2.44 Hz changing on timescales of a few days and an rms amplitude between 8% and 12%, and it was detected in the persistent emission during dips and during type I X-ray bursts. During one observation, when the count rate was a factor of 2-3 higher than otherwise, the QPO was not detected. The strength of the QPO did not significantly depend on photon energy and is consistent with being the same in the persistent emission, both during and outside the dips and during type I X-ray bursts. Frequency shifts were observed during three of the four X-ray bursts. We argue that the QPO is produced by the same mechanism as the QPO recently found by Jonker et al. in 4U 1323-62. Although the exact mechanism is not clear, it is most likely related to the high inclination of both systems. An orbiting structure in the accretion disk that modulates the radiation from the central sourer seems the most promising mechanism.

Original languageEnglish
Pages (from-to)pp.L91-L94.
Number of pages4
JournalAstrophysical Journal
Volume516
Issue number2
Publication statusPublished - 10 May 1999

Keywords

  • accretion, accretion disks
  • stars : individual (EXO 0748-676)
  • stars : neutron
  • X-rays : stars
  • 4U 1915-05
  • DISCOVERY

Fingerprint

Dive into the research topics of 'A Variable 0.58-2.44 HZ Quasi-periodic Oscillation in the Eclipsing and Dipping Low-Mass X-Ray Binary EXO 0748-676'. Together they form a unique fingerprint.

Cite this