Overview

• Researchers from ISRO’s U R Rao Satellite Centre, IIT Guwahati and Haifa University analyzed AstroSat’s time-resolved observations of GRS 1915+105.
• They detected rapid X-ray flickering at about 70 Hz that appears exclusively during high-brightness intervals lasting several hundred seconds.
• Detailed spectral analysis shows the corona becomes more compact and hotter during bright phases, driving the fast oscillations before cooling and expanding in dim intervals.
• The study offers the first observational link between high-frequency X-ray variability and dynamic changes in the corona of a stellar-mass black hole.
• The discovery provides a new observational constraint for theoretical models of black hole accretion and emission and sets the stage for follow-up modeling and multiwavelength observations.