Recently, astronomers made a groundbreaking discovery that has astounded the scientific community. A neutron star merged with a surprisingly light black hole, an event that had never been observed before. This rare collision was detected by the fourth LIGO-Virgo-KAGRA observing session, which picked up gravitational waves from a distant location 650 million light years away. What made this event particularly intriguing was the size of the black hole involved, which had a mass between 2.5 to 4.5 times that of the Sun.

Neutron stars and black holes are both remnants of massive stars that have reached the end of their lifespan. When a star runs out of nuclear fuel, the inward pull of gravity causes its core to collapse. For low-mass stars like the Sun, this collapse results in the formation of a neutron star. However, for more massive stars, the core collapse leads to the creation of a black hole, which is an object with such a strong gravitational pull that not even light can escape from it.

The recent merger event, detected in May 2023, involved an object with a mass of 1.2 times that of the Sun and another slightly larger object, which scientists believe was a neutron star and a low-mass black hole, respectively. The black hole in question fell into a category known as the ‘mass gap’, which refers to objects that are more massive than the most massive neutron stars but less massive than the least massive black holes.

Gravitational waves are ripples in space-time that are generated when massive objects interact with each other. Before the first detection of gravitational waves in 2015, black holes were typically observed through X-ray emissions, while neutron stars were detected using radio observations. The ‘mass gap’ between the two categories of objects has been a subject of debate among scientists, with some arguing that there may be more objects in this mass range than previously thought.

Detecting and studying objects in the ‘mass gap’ poses a significant challenge due to the sensitivity of current detectors. Researchers are continuously working to improve the performance of instruments such as the LIGO detectors by enhancing mirror coatings and upgrading data analysis software. The recent discovery has opened up new possibilities for understanding the nature of compact objects in this mass range and has spurred further research into improving detection capabilities.

As scientists delve deeper into the data obtained from the LIGO-Virgo-KAGRA network, they hope to uncover more insights into the merging of neutron stars with black holes and shed light on the mysteries of the universe. The collaboration between international observatories and research institutions has paved the way for a new era of discovery in gravitational wave astronomy.

Source: New gravitational wave signal helps fill the ‘mass gap’ between neutron stars and black holes