Indian researchers have reported a new explanation for one of the intriguing features of black holes: the rapid, sometimes nearly regular flickering of X-rays emitted by matter in their vicinity.
The research, reported by the Press Information Bureau on October 23, 2026, was conducted by scientists at ARIES in collaboration with researchers from the Nicolaus Copernicus Astronomical Center in Poland and Mahatma Jyotiba Phule Rohilkhand University in Bareilly, Uttar Pradesh.
Editorial Insight
Key Highlights
Important points readers should notice.
Issue/Event: Research into the effect of black hole spin on X-ray flickering.
Location: ARIES, India, with international research collaboration.
Authority/Organisation: Department of Science and Technology, Government of India; ARIES; collaborating academic institutions.
Action Taken: Researchers used numerical simulations to model matter flowing around spinning black holes.
Impact: The findings may help explain observed X-ray oscillations and improve theoretical models of black hole environments.
The team investigated how the spin of a black hole affects the movement of matter falling towards it and the resulting variations in emitted radiation. Their work focuses on quasi-periodic oscillations, commonly known as QPOs, which are patterns of brightness variation observed in X-ray emissions from certain black hole systems.
Black holes are regions of space where gravity is so strong that nothing, including light, can escape from within the event horizon. Although the black hole itself cannot emit escaping light from inside that boundary, the hot matter surrounding it can produce intense radiation as it moves through the extreme gravitational environment.
That surrounding material can form an accretion flow or disc. As the matter moves inward, its physical conditions change, creating radiation that astronomers can observe with specialised instruments.
Editorial Analysis
Why This Matters
The study offers a way to connect the observed behaviour of X-rays with the physics of matter moving close to a black hole. Improved models of quasi-periodic oscillations could help astronomers interpret signals from X-ray binary systems and investigate the influence of black hole spin. It also demonstrates how computational astrophysics can complement telescope observations when direct measurements of extreme environments are impossible. The research remains a theoretical modelling result, and its broader usefulness will depend on how well its predictions match observations across different black hole systems.
The brightness of this radiation sometimes varies in patterns that appear nearly periodic. Understanding what produces these variations can help scientists investigate the physical processes occurring close to black holes.
How black hole spin affects the flickering
The research team used numerical simulations to study viscous accretion flows around spinning black holes. Viscosity describes internal friction within a flowing material and can influence how matter moves and how structures develop within the flow.
The simulations examined how shock waves in the accretion flow behave under different conditions. A shock is a region where the physical properties of the flow change sharply. Under certain conditions, a shock that would otherwise remain relatively stable can begin oscillating.
According to the findings described by the Department of Science and Technology, these oscillations can help explain the quasi-periodic changes in radiation detected from black hole systems.
The researchers found that black hole spin has a significant influence on the average position and behaviour of the oscillating shock.
In their simulations, slowly spinning black holes tended to have shock structures positioned farther from the black hole, producing predominantly lower-frequency oscillations. In rapidly spinning systems, the shock could move closer to the black hole, allowing a wider range of frequencies to emerge.
For a black hole with a mass approximately ten times that of the Sun, the model predicts that some oscillation frequencies could exceed 100 hertz under conditions involving very high spin.
A frequency of 100 hertz corresponds to 100 cycles per second. These are rapid variations that astronomers study to understand the energetic processes occurring close to compact objects.
The result provides a possible physical explanation for why different black hole systems can display X-ray fluctuations at substantially different frequencies.
Why the researchers used computer simulations
The environment around a black hole is difficult to investigate directly. Scientists cannot send instruments into the region close to the event horizon and retrieve them for conventional measurements.
Instead, researchers combine astronomical observations with mathematical models, computer simulations and the laws of physics to test explanations for what telescopes detect.
The ARIES team used a numerical framework developed by its Numerical and Theoretical Astrophysics Group to model the movement of matter around black holes. The simulations were designed to account for important physical quantities, including mass, energy and momentum.
The study also examined how the relationship between oscillation frequency and the spectral characteristics of the emitted radiation could provide further clues about the system.
These results do not mean that scientists have directly observed every simulated shock movement. Rather, the simulations offer a theoretical explanation that can be compared with observations from black hole X-ray binaries.
The findings were reported as a study published in the Journal of High Energy Astrophysics. The publication provides a basis for further scientific examination of the model and its predictions.
What the discovery means for astronomy
Quasi-periodic oscillations are valuable because they can carry information about the physical conditions in the innermost regions of accretion flows.
If scientists can better understand how the spin of a black hole influences these patterns, they may be able to interpret observed X-ray signals more accurately.
The research could help astronomers compare theoretical predictions with measurements from black hole X-ray binaries and improve models of matter moving under extreme gravitational conditions.
However, the findings are not a new direct image of a black hole, nor do they establish a universal method for measuring black hole spin from flickering alone. Further observations and independent studies will be important in determining how well the model applies to different systems.
The work highlights the contribution of Indian astrophysics researchers to the study of some of the universe's most extreme objects.
