We interpret the correlation over 5 orders of magnitude between high frequency νhigh and low frequency νlow in quasi-periodic oscillations (QPOs) found by Psaltis, Belloni, & van der Klis for black hole (BH) and neutron star (NS) systems and then extended by Mauche to white dwarf (WD) binaries. The observed correlation strongly constrains theoretical models and provides clues to understanding the nature of the QPO phenomena at large. We argue that the observed correlation is a natural consequence of the Keplerian disk flow adjustment to the innermost sub-Keplerian boundary conditions near the central object that ultimately leads to the formation of the sub-Keplerian transition layer (TL) between the adjustment radius and the innermost boundary (the star surface for the NS and WD and the horizon for the BH). In the frameworks of the TL model, νhigh is related to the Keplerian frequency at the outer (adjustment) radius ν_K, and ν_low is related to the magnetoacoustic oscillation frequency ν_MA. Using a relation between ν_MA, the magnetic and gas pressure, and the density and the hydrostatic equilibrium condition in the disk, we infer a linear correlation between ν_K and ν_MA. Identification of ν_high, νlow with ν_K, ν_MA, respectively, leads us to the determination of H/r_out=1.5×10^{-2} and β=0.1 (where H is the half-width of the disk and β is a ratio of magnetic pressure to gas pressure). We estimate the magnetic field strength near the TL outer radius for BHs, NSs, and WDs. The fact that the observed high-low frequency correlation over 5 orders of magnitude is valid for BHs, NSs, and down to WDs strongly rules out relativistic models for QPO phenomena. We come to the conclusion that the QPO observations indicate the adjustment of the geometrically thin disk to sub-Keplerian motion near the central object. This effect is a common feature for a wide class of systems, starting from WD binaries up to BH binaries.

On the Low and High Frequency Correlation in Quasi-periodic Oscillations among White Dwarf, Neutron Star, and Black Hole Binaries

TITARCHUK, Lev;
2002

Abstract

We interpret the correlation over 5 orders of magnitude between high frequency νhigh and low frequency νlow in quasi-periodic oscillations (QPOs) found by Psaltis, Belloni, & van der Klis for black hole (BH) and neutron star (NS) systems and then extended by Mauche to white dwarf (WD) binaries. The observed correlation strongly constrains theoretical models and provides clues to understanding the nature of the QPO phenomena at large. We argue that the observed correlation is a natural consequence of the Keplerian disk flow adjustment to the innermost sub-Keplerian boundary conditions near the central object that ultimately leads to the formation of the sub-Keplerian transition layer (TL) between the adjustment radius and the innermost boundary (the star surface for the NS and WD and the horizon for the BH). In the frameworks of the TL model, νhigh is related to the Keplerian frequency at the outer (adjustment) radius ν_K, and ν_low is related to the magnetoacoustic oscillation frequency ν_MA. Using a relation between ν_MA, the magnetic and gas pressure, and the density and the hydrostatic equilibrium condition in the disk, we infer a linear correlation between ν_K and ν_MA. Identification of ν_high, νlow with ν_K, ν_MA, respectively, leads us to the determination of H/r_out=1.5×10^{-2} and β=0.1 (where H is the half-width of the disk and β is a ratio of magnetic pressure to gas pressure). We estimate the magnetic field strength near the TL outer radius for BHs, NSs, and WDs. The fact that the observed high-low frequency correlation over 5 orders of magnitude is valid for BHs, NSs, and down to WDs strongly rules out relativistic models for QPO phenomena. We come to the conclusion that the QPO observations indicate the adjustment of the geometrically thin disk to sub-Keplerian motion near the central object. This effect is a common feature for a wide class of systems, starting from WD binaries up to BH binaries.
Titarchuk, Lev; Wood, K.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11392/532988
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 36
  • ???jsp.display-item.citation.isi??? 36
social impact