Researchers from the Indian Institute of Technology (IIT) Guwahati, in collaboration with the UR Rao Satellite Centre, Indian Space and Research Organisation (ISRO), and Haifa University, Israel, have decoded a mysterious X-ray signal pattern from the black hole GRS 1915+105, located approximately 28,000 light-years from Earth.

Utilising data from India’s AstroSat space observatory, the team observed that the X-ray brightness alternates between bright and dim phases, each lasting several hundred seconds.

Understanding black hole dynamics

Global researchers are focused on unraveling the mysteries of black holes, which generate extreme heat and emit X-rays by drawing gas from companion stars. Analysing these X-rays provides insights into the extreme environments near black holes, shedding light on their behavior and influence.

X-ray flickering patterns

The study revealed that the X-ray brightness from GRS 1915+105 alternates between two distinct phases: a bright phase with strong flickering and a dim phase where flickering ceases. During the bright phase, the corona, a region of hot plasma surrounding the black hole, becomes more compact and significantly hotter.

In contrast, during the dim phase, it expands and cools. This correlation suggests the oscillating corona is the source of the rapid flickering signals.

Corona’s dynamic behaviour

Each phase, lasting several hundred seconds, repeats in a regular pattern, with rapid flickering observed only during the bright phase. This indicates that the corona is not a static structure but dynamically changes in shape and energy based on the inflow of gases into the black hole.

Implications for black hole research

The findings enhance our understanding of the extreme gravitational forces, and high temperatures near a black hole’s edge. They refine models of how black holes grow, release energy, and impact their cosmic surroundings, offering clues about their role in shaping galaxy evolution.