Evidence of Class Transitions in GRS 1915+105 from Indian X-Ray Astronomy Experiment Data

GRS 1915+105 shows at least 12 distinct classes of light curves. By analyzing the data obtained from the Indian X-ray Astronomy Experiment (IXAE) instrument on board the IRS-P3 satellite, we show that on several days, transitions between one class to another were observed. On these days, the so-called κ class went to ρ class and the χ class went to ρ class. In the frequency-time plane, such transitions exhibited change in quasi-periodic oscillation (QPO) frequency. We could detect that low-frequency QPOs occurred in anticipation of a class transition several hundred minutes before the actual transition.