Correlation of the Quasi‐Periodic Oscillation Frequencies of White Dwarf, Neutron Star, and Black Hole Binaries

Abstract

Using data obtained in 1994 June/July with the Extreme Ultraviolet Explorer deep survey photometer and in 2001 January with the Chandra X-ray Observatory Low Energy Transmission Grating Spectrograph, we investigate the extreme-ultraviolet (EUV) and soft X-ray oscillations of the dwarf nova SS Cyg in outburst. We find quasi-periodic oscillations (QPOs) at ν 0 ≈ 0.012 Hz and ν 1 ≈ 0.13 Hz in the EUV flux and at ν 0 ≈ 0.0090 Hz, ν 1 ≈ 0.11 Hz, and possibly ν 2 ≈ ν 0 +ν 1 ≈ 0.12 Hz in the soft X-ray flux. These data, combined with the optical data of Woudt & Warner for VW Hyi, extend the Psaltis, Belloni, & van der Klis ν high -ν low correlation for neutron star and black hole low-mass X-ray binaries (LMXBs) nearly two orders of magnitude in frequency, with ν low ≈ 0.08 ν high . This correlation identifies the high-frequency quasi-coherent oscillations (so-called "dwarf nova oscillations") of cataclysmic variables (CVs) with the kilohertz QPOs of LMXBs, and the low-frequency QPOs of CVs with the horizontal branch oscillations (or the broad noise component identified as such) of LMXBs. Assuming that the same mechanisms produce the QPOs in white dwarf, neutron star, and black hole binaries, we find that the data exclude the relativistic precession model and the magnetospheric and sonic-point beat-frequency models (as well as any model requiring the presence or absence of a stellar surface or magnetic field); more promising are models that interpret QPOs as manifestations of disk accretion onto any low-magnetic field compact object.

Global Disk Oscillation Modes in Cataclysmic Variables and Other Newtonian Accretors

“…Its value should be only moderately greater than the white dwarf radius R for those magnetic field strengths thought to be present in many of those white dwarf systems which exhibit DNOs. For example, the value of d log P/d log L ¼ À0:091 for the dwarf nova SS Cygni reported by Mauche (1996) is reproduced by our formalism provided ¼ 0:06.…”

Dwarf Nova Oscillations and Quasi-Periodic Oscillations: Extension of the Two-QPO Diagram of X-Ray Binaries, and a new kind of DNO

“…Interpreting the DNOs and QPOs in VW Hyi as analogues of the high and low frequency QPOs observed in X-Ray binaries, we showed that VW Hyi lies on an extension to low frequencies of the two-QPO correlation in X-Ray binaries found by Psaltis, Belloni & van der Klis (1999). An important addition to this correlation was made by Mauche (2002), who found that the X-Ray DNOs and QPOs in SS Cyg also fall on this relationship, which helps to close the gap between the CVs and the X-Ray binaries.…”

QPOs in cataclysmic variables and in X-ray binaries

“…We digress to note that the mechanism of QPO formation has previously been suggested to be common to sources as diverse as black holes and white dwarfs based on a linear relationship between two frequencies in LMXBs (Wijnands & van der Klis, 1999;Psaltis et al, 1999;Belloni et al, 2002), later extended to cataclysmic variables (Mauche, 2002;. Because orbital motion around white dwarfs is accurately described by Newtonian gravity this seemed to rule out the few models, such as the so called relativistic precession model, in which all QPO frequencies can be related to general relativistic frequencies (Mauche, 2002;.…”