About a decade ago Kotov & Koutchmy (1985) suggested that the 160-min period might be connected with disturbances in the gravitational field. At those times, the development of this hypothesis has led to stormy discussions on possible monochromatic 160-min GW induced by a distant, massive and very energetic source, e.g., by the binary - and X -ray system Geminga (Delache 1983; Arvonny 1983; Walgate 1983), which was supposed to stimulate solar oscillations with the 160-min period. However, it was almost immediately shown (Anderson et al. 1984; Fabian & Gough 1984; Bonazzola et al. 1984; Kuhn & Boughn 1984; Caroll et al. 1984) that if the general concept of GR is correct, this oscillation in the Sun could not have been driven to the observable amplitude by any binary source of stellar mass.
Irrespective of other explanations of the -resonance observed in period distribution of close binaries, we consider it interesting to speculate that it might be of interest for the study and detection of GR (or QGR) in the Universe.
Since (a) the absolute majority of binaries under consideration have periods , and (b) the two possible resonant effects, A and B, emerge as -peaks of opposite sign (positive and negative, respectively), the action of a hypothetical GW (QGW), can be formulated also this way: A -resonance - an excess of binaries at periods (odd commensurability), and B -resonance - a lack of binaries at periods (even non-commensurability).
One of possibilities for the remarkable emergence of the 160-min peak in the period distribution of CBS's (Figs. 1 and 7), might be, e.g., a (hypothetical) mechanism of resonant excitation of this -oscillation (of the gravitational field) by CBS's themselves. The latter, being numerous, might induce enhanced GW's (QGW's) at frequencies which, in turn, produce a substantial excess of systems with those frequencies, and also a lack of systems with frequencies which are even-commensurate with Hz, i.e. with .
The phenomenon might relate also to some peculiar property of gravitation and time, and perhaps to cosmology. In conclusion, we would like also to refer to the recent discovery (Kotov et al. 1994) of the same -periodicity in luminosity variations of the most massive single objects of the Universe - the active galactic nuclei. The existence of a -oscillation (or, equally, of the -periodicity) in the total sample of galactic CBS's, and also plausibly in AGN's, could yield a crucial insight into the true intrinsic nature of those objects.
© European Southern Observatory (ESO) 1997
Online publication: June 30, 1998