Correlations in quasi-periodic oscillation and noise frequencies among neutron star and black hole X-ray binaries

Dimitrios Psaltis, Tomaso Belloni, Michiel Van Der Klis

Research output: Contribution to journalArticle

232 Scopus citations


We study systematically the ≃0.1-1200 Hz quasi-periodic oscillations (QPOs) and broad noise components observed in the power spectra of nonpulsing neutron star and black hole low-mass X-ray binaries. We show that among these components we can identify two, occurring over a wide range of source types and luminosities, whose frequencies follow a tight correlation. The variability components involved in this correlation include neutron star kilohertz QPOs and horizontal-branch oscillations, as well as black hole QPOs and noise components. Our results suggest that the same types of variability may occur in both neutron star and black hole systems over 3 orders of magnitude in frequency and with coherences that vary widely but systematically. Confirmation of this hypothesis will strongly constrain theoretical models of these phenomena and provide additional clues to understanding their nature.

Original languageEnglish (US)
Pages (from-to)262-270
Number of pages9
JournalAstrophysical Journal
Issue number1 PART 1
StatePublished - Jul 20 1999



  • Accretion, accretion disks
  • Black hole physics
  • Stars: neutron
  • Stars: oscillations
  • X-rays: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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