Nasa’s Webb telescope may have spotted whole new type of star that unravels one of universe’s mysteries

Research predicts how dark matter may have played part in formation of some of universe’s earliest stars

Vishwam Sankaran
Friday 14 July 2023 09:32 BST
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Nasa’s James Webb Space Telescope has spotted three bright objects astronomers suspect could be monster-size objects powered by annihilating particles of dark matter.

If confirmed, the results, published in the journal PNAS, could reveal fresh insights on the type of matter that remains one of the most unsolved problems in the entirety of physics.

Dark matter is a theorised, but undiscovered component of the universe, the presence of which is predicted based on its gravitational attraction, as it does not absorb, reflect or emit light, making it extremely difficult to spot.

“Discovering a new type of star is pretty interesting all by itself, but discovering it’s dark matter that’s powering this – that would be huge,” said study co-author Katherine Freese from The University of Texas in Austin.

Although estimates say dark matter makes up about a quarter of the known universe, its nature has eluded scientists, who suspect it could be formed by a new type of undiscovered, elementary particle.

A main candidate for such a particle is the theorised Weakly Interacting Massive Particles.

These particles are suspected to annihilate themselves when they collide, depositing heat into collapsing clouds of hydrogen and converting them into brightly shining dark stars.

The identification of such supermassive “dark stars” – which could grow to be several million times the mass of the sun and up to 10 billion times as bright – may open new doors to understanding dark matter.

Dark stars could also unravel one of the mysterious observations of the Webb telescope that suggests there are too many large galaxies in the early universe to fit the predictions of the origin and fate of the cosmos.

“It’s more likely that something within the standard model [of cosmology] needs tuning, because proposing something entirely new, as we did, is always less probable,” Dr Freese said.

“But if some of these objects that look like early galaxies are actually dark stars, the simulations of galaxy formation agree better with observations,” she explained.

The three likely dark stars – JADES-GS-z13-0, JADES-GS-z12-0 and JADES-GS-z11-0 – were originally identified as galaxies last December.

Research suggested they existed about 320-400 million years after the Big Bang, making them some of the earliest objects ever seen.

A new analysis of data, however, suggests there are two competing possibilities for these objects.

“One is that they are galaxies containing millions of ordinary, population-III stars. The other is that they are dark stars. And believe it or not, one dark star has enough light to compete with an entire galaxy of stars,” Dr Freese explained.

Scientists have theorised what dark matter could likely do to the formation of some of the first stars in the universe.

They suspect very dense clumps of dark matter could have existed at the centres of early galaxies along with clouds of hydrogen and helium gas.

As the gas cooled, it would have collapsed and pulled in dark matter along with it.

The dark matter particles would have then increasingly annihilated due to the increasing density from the clumping, adding more and more heat.

This, scientists suspect, would have prevented the gas from collapsing all the way down to support fusion as is seen in an ordinary star.

Instead, the cloud would have continued to gather more gas and dark matter, becoming “big, puffy and much brighter than ordinary stars”.

As a result of this unique star formation process, in dark stars, unlike in their ordinary stellar counterparts, the power source would be evenly spread out rather than concentrated in the core.

And with enough dark matter, these mysterious stars could grow to a monster size and brightness as well.

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