TIMESCALE INVARIANCE OF RAPID X-RAY VARIABILITY OF THE BLACK-HOLE CANDIDATE GRO J1719-24

We present the results of an analysis of the time variability of the s oft X-ray transient GRO J1719-24 (Nova Oph 1993), as observed with BAT SE. Our analysis covers the entire similar to 80 day outburst, beginni ng with the first detection of this black hole candidate on 1993 Septe mber 25. We obtained power density spectra (PDSs) of the data in the 2 0-100 keV energy band, covering the frequency interval 0.002-0.488 Hz. The PDSs show a significant quasi-periodic oscillation peak, the cent roid frequency of which increased from similar to 0.04 Hz at the onset of the outburst to similar to 0.3 Hz at the end. Additional noise is present in the PDSs, which we describe in terms of two components. We find that the evolution of the PDSs can be described as a gradual stre tching by a factor of similar to 7.5 in frequency of the power spectru m, accompanied by a decrease of the power level by the same factor, su ch that the integrated power in a scaled frequency interval remains co nstant.