Overview

• Researchers from IIT Guwahati, ISRO’s U. R. Rao Satellite Centre, and Haifa University used India’s AstroSat to study the microquasar GRS 1915+105 about 28,000 light-years away.
• They report rapid X-ray flickering at roughly 70 times per second that appears only during high-brightness intervals and disappears in low-brightness intervals, described as the first evidence of such behavior in this source.
• The object alternates between long bright and dim phases lasting several hundred seconds, allowing the team to isolate when the fast signal emerges.
• The study links the fast oscillations to a compact, hotter corona in bright phases, whereas an expanded, cooler corona in dim phases suppresses the signal.
• The findings, published in Monthly Notices of the Royal Astronomical Society, highlight AstroSat’s capability and, the authors say, refine models of accretion-driven radiation and feedback.