Astronomers from the Raman Research Institute (RRI) have uncovered new clues about a strange and powerful object in space that emits bursts of X-rays in an unusual pattern.
Their findings suggest that a “wobbling” disk of matter around the object could be behind these mysterious signals.
The object, known as ULX M74 X-1, lies in a distant spiral galaxy and belongs to a class of sources called ultraluminous X-ray sources (ULXs). These are among the brightest X-ray emitters in the universe and are powered by extremely dense objects like black holes or neutron stars, pulling in matter from nearby stars.
What makes ULX M74 X-1 especially intriguing is its behaviour. It produces sudden bursts of energy, or “flares,” that repeat over time, but not in a regular pattern. Each flare lasts about half an hour, and scientists have long been puzzled about what causes this irregular rhythm.
To investigate, Aman Upadhyay, PhD student in the Astronomy and Astrophysics division at RRI, and colleagues, analysed data collected over two decades by Nasa’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton telescope.
They found that the object behaves differently during flaring and non-flaring periods.
During flares, signs point to strong winds blowing material away from the disk of matter surrounding the object. At other times, the inner, brighter region of the disk becomes more visible.
The team believes this changing view could be caused by the disk itself wobbling, similar to how a spinning top shifts as it rotates. As the disk tilts, the wind moves in and out of the telescope’s line of sight. This would make the object appear to brighten and dim in an irregular way, explaining the unusual flare pattern.
The study also sheds light on the nature of the object at the centre. Earlier research suggested it might be a rare intermediate-mass black hole. However, the new analysis indicates it is more likely a smaller, stellar-mass black hole, about seven times the mass of the Sun.
There is also a possibility that it could be a neutron star, another type of dense cosmic object.
Scientists now plan to search for specific signals that could confirm its true identity. If proven, the findings could help explain how some of the universe’s brightest X-ray sources work and why they behave so unpredictably.
