Is it the lightest black hole or the heaviest neutron star? MeerKAT discovers a mysterious object in the Milky Way

An international team of astronomers has discovered a new, previously unknown object that is more massive than the heaviest known neutron star, but also lighter than the lightest known black hole.

Astronomers from a number of institutions, including the University of Manchester and the Max Planck Institute for Radio Astronomy in Germany, are using the MeerKAT radio telescope to locate and rotate rapidly within a dense cluster of stars some 40,000 light-years away. discovered a celestial object in orbit around a millisecond pulsar. It is known as a globular cluster.

They used clock-like sounds from millisecond pulsars to show that this massive object is in the so-called black hole mass gap.

This could be the first discovery of a long-awaited radio pulsar, a binary black hole. This exciting combination could enable new tests of Einstein’s general theory of relativity and open the door to the study of black holes.

The results are as follows published in a diary Science.

Ben Stappers, the British project leader and professor of astrophysics at the University of Manchester, said: “Both possibilities about the nature of the companion star are interesting. A pulsar-black hole system could be used to test theories of gravity and massive neutron stars. It will become an important target.” It will provide new insights in extremely dense nuclear physics. ”

A neutron star (the ultra-dense remnant of a dead star) collapses when it gains too much mass, usually by consuming or colliding with another star. There is much speculation about what will happen to them after they collapse, but it is thought that they could become black holes. A black hole is an object whose gravity is so strong that not even light can escape from it.

Astronomers believe that the total mass required for a neutron star to collapse is 2.2 times the mass of the Sun. The theory, supported by observations, suggests that the lightest black holes created by these stars are much larger, about five times more massive than the Sun, creating what is known as the “black hole mass gap.”

The nature of the compact object in this mass gap is unknown, and detailed study has so far proven difficult. The discovery of objects may help us ultimately understand these objects.

Professor Stappers added: “The ability of the highly sensitive MeerKAT telescope to reveal and study these objects allows us to take a huge step forward and provides a glimpse of what will be possible with square kilometer arrays.” Ta.

The discovery of this object was made while using the MeerKAT telescope to observe a large star cluster known as NGC 1851 south of the constellation Columba.

Globular cluster NGC 1851 is a dense collection of older stars that are much denser than the rest of the galaxy. It’s so crowded here that stars can interact with each other, disrupt their orbits, and in the most extreme cases even collide.

Astronomers, part of the international Transients and Pulsars (TRAPUM) collaboration with MeerKAT, say that two neutrons have been proposed to have created the massive object currently orbiting the radio pulsar. It is thought to be an interstellar collision.

The research team was able to detect a faint pulse from one of the stars and identified it as a radio pulsar. A radio pulsar is a type of neutron star that rotates at high speed and beams radio beams into space like a cosmic lighthouse.

The pulsar rotates more than 170 times per second, producing a rhythmic pulse similar to the ticking of a clock. The ticks of these pulses are incredibly regular, and their orbital motion can be measured with great precision by observing how the ticks change in time using a technique called pulsar timing. is completed.

Euan Bahr of the Max Planck Institute for Radio Astronomy, who led the study with colleague Arunima Dutta, said: “We dropped a near-perfect stopwatch into orbit around a star nearly 40,000 light-years away. , and then time those orbits with microsecond precision.”

The regular timing also allows us to measure the system’s position very precisely, showing that the objects in the pulsar’s orbit are not normal stars, but very dense remnants of collapsed stars. it was done. Observations showed that the companion star is more massive than any known neutron star, but also smaller than any known black hole, placing it within the black hole’s mass gap.

The researchers cannot conclusively say whether they have discovered the heaviest known neutron star, the lightest known black hole, or a new exotic star variant. , what is certain is that they have discovered a unique laboratory for investigating the properties of matter under the most demanding conditions. The ultimate state of the universe.

Arunima Dutta concludes: “This system is not finished yet.

“Uncovering the true nature of the companion star will be a turning point in our understanding of neutron stars, black holes, and what else may lurk in the mass gap of a black hole.”