Astrophysics in crisis? Mysterious object discovered that could change everything | Top Vip News

Astronomers discover a celestial object that defies classification, possibly discovering a new type of cosmic entity at the edge of known physics.

Sometimes astronomers come across objects in the sky that we can’t easily explain. In our new research, published in ScienceWe report such a discovery, which is likely to spark debate and speculation.

Neutron stars are some of the densest objects in the universe. As compact as an atomic nucleus, but as large as a city, they exceed the limits of our understanding of extreme matter. The heavier a neutron star is, the more likely it is to eventually collapse and become something even denser: a black hole.

The edge of understanding: neutron stars and black holes

These astrophysical objects are so dense and their gravitational forces so strong that their cores (whatever they may be) are permanently hidden from the universe by event horizons: surfaces of perfect darkness from which light cannot escape.

If we ever want to understand the physics at the tipping point between neutron stars and black holes, we must find objects at this boundary. In particular, we need to find objects that we can make precise measurements of over long periods of time. And that is precisely what we have found: an object that is not obviously a neutron star not one black hole.

A cosmic dance in NGC 1851

It was by looking deep into the star cluster. NGC 1851 We saw what appear to be a pair of stars that offer a new view of the extremes of matter in the universe. The system is made up of one millisecond. pressa type of rapidly spinning neutron star that sweeps rays of radio light across the cosmos as it spins, and a massive, hidden object of unknown nature.

The massive object is dark, meaning it is invisible in all frequencies of light, from radio to optical, X-ray and gamma-ray bands. Under other circumstances, this would make it impossible to study, but this is where the millisecond pulsar comes to our aid.

Millisecond pulsars are similar to cosmic atomic clocks. Their spins are incredibly stable and can be accurately measured by detecting the regular radio pulse they create. Although intrinsically stable, the observed spin changes when the pulsar is in motion or when its signal is affected by a strong gravitational field. By observing these changes we can measure the properties of bodies in orbits with pulsars.

Revealing the mystery with MeerKAT

Our international team of astronomers has been using the MeerKAT radio telescope in South Africa to make such observations of the system, called NGC 1851E.

This allowed us to precisely detail the orbits of the two objects, showing that their point of closest approach changes over time. These changes are described by Einstein’s theory of relativity and the speed of a change tells us about the combined mass of the bodies in the system.

Our observations revealed that the NGC 1851E system weighs almost four times as much as our Sun and that its dark companion was, like the pulsar, a compact object, much denser than a normal star. The most massive neutron stars weigh around two solar masses, so if this were a double neutron star system (systems that are well known and studied), then it would have to contain two of the heaviest neutron stars ever. found.

To discover the nature of the companion, we would need to understand how the system’s mass was distributed among the stars. Using Einstein’s general relativity again, we were able to model the system in detail, finding that the mass of its companion is between 2.09 and 2.71 times the mass of the Sun.

The mass of its companion falls within the “black hole mass gap” that lies between the heaviest possible neutron stars, which are thought to be around 2.2 solar masses, and the lightest black holes. that can form from a stellar collapse, around 5 solar masses. The nature and formation of the objects in this gap is an open question in astrophysics.

Possible candidates

So what exactly have we found?

A tantalizing possibility is that we have discovered a pulsar orbiting the remains of a merger (collision) of two neutron stars. This unusual configuration is possible thanks to the dense concentration of stars in NGC 1851.

On this packed stellar dance floor, the stars will spin around each other, exchanging partners in an endless waltz. If two neutron stars get too close, their dance will come to a catastrophic end.

The black hole created by their collision, which may be much lighter than those created by collapsing stars, is then free to wander around the cluster until it finds another pair of dancers in the waltz and, rather rudely, inserts itself. , expelling the lighter companion. in the process. It is this mechanism of collisions and exchanges that could give rise to the system we observe today.

Continuing the search

We are not done with this system yet. Work is already underway to conclusively identify the true nature of its companion and reveal whether we have discovered the lightest black hole or the most massive neutron star, or perhaps neither.

At the boundary between neutron stars and black holes there is always the possibility that some new, as yet unknown, astrophysical object exists.

There will surely be a lot of speculation following this discovery, but what is already clear is that this system holds immense promise when it comes to understanding what really happens to matter in the most extreme environments of the universe.

Written by:

• Ewan D. Barr – Project Scientist for Transients and Pulsars with the collaboration of MeerKAT (TRAPUM), Max Planck Institute for Radio Astronomy
• Arunima Dutta – PhD Candidate at the Department of Fundamental Physical Research in Radio Astronomy, Max Planck Institute for Radio Astronomy
• Benjamin Stappers – Professor of Astrophysics, University of Manchester

Adapted from an article originally published in The conversation.