The Webb Space Telescope catches a glimpse of the first possible “dark stars.”

Dark matter-powered stars still need to be proven, but could reveal clues about the nature of one of the universe’s great mysteries.

Fusion causes stars to radiate light from the darkness of space as atoms fuse together and release energy. But what if there was another way to strengthen a star?

A team of three astronomers — in collaboration with Kathryn Freese and Cosmin Ailey of the University of Texas at Austin and Jillian Paulin ’23 of Colgate University — analyzed the images. James Webb Space Telescope (JWST) discovered three bright objects that could be “dark stars,” theoretical objects much larger and brighter than our Sun, powered by particles that destroy dark matter. If confirmed, dark stars could reveal the nature of dark matter, one of the deepest unsolved problems in all of physics.

“Finding a new type of star is very interesting, but finding that it’s powered by dark matter would be huge,” said Freese, director of the Weinberg Institute for Theoretical Physics and the Jeff and Gail Kodosky Endowed Chair in Physics. at UT Austin.

Three of these objects (JADES-GS-z13-0, JADES-GS-z12-0, and JADES-GS-z11-0) were identified as galaxies by the JWST Advanced Deep Extragalactic Survey (JADES) in December 2022. Now, a team including Katherine Freese of the University of Texas at Austin speculates that they may actually be “dark stars,” theoretical objects much larger and brighter than our Sun, powered by particles that destroy dark matter. Credit: NASA/ESA

Although about 25% of the universe is dark matter, its nature has eluded scientists. Scientists believe it contains a new type of elementary particle, and the hunt for such particles continues. Leading candidates include weakly interacting massive particles. When they collide, these particles annihilate themselves and deposit heat into collapsing clouds of hydrogen, turning them into glowing dark stars. Identifying supermassive dark stars will open up the possibility of studying dark matter based on their observed properties.

The research was published on July 11 Proceedings of the National Academy of Sciences.

Follow-up observations from JWST of the objects’ spectroscopic properties — whether the light intensity decreases or increases in certain frequency bands — will help confirm whether these candidate objects are indeed dark stars.

Confirming the existence of dark stars may also help solve a problem posed by JWST: It appears that there were many massive galaxies in the early universe to fit the predictions of the Standard Model of cosmology.

“It’s more likely that some tuning will be needed within the standard model because it’s always less likely to propose something completely new like we did,” Freese said. “But if some of these objects that look like early galaxies are actually dark stars, the simulations of galaxy formation agree well with the observations.”

Three candidate dark stars (JADES-GS-z13-0, JADES-GS-z12-0, and JADES-GS-z11-0) were originally identified as galaxies Using spectroscopic analysis by the JWST Advanced Deep Extragalactic Survey (JADES) in December 2022, the JADES team confirmed the objects. It has been observed since about 320 million to 400 million years after the Big Bangmaking them the earliest objects ever seen.

“When we look at the James Webb data, there are two competing possibilities for these objects,” Freese said. “One is that they are galaxies containing millions of normal, population-III stars. The other is that they are dark stars. Believe it or not, a dark star has enough luminosity to compete with an entire star.

Dark stars can theoretically grow to millions of times the mass of our Sun and up to 10 billion times brighter than the Sun.

“We prophesied back In 2012, JWST was able to observe the spectacular dark stars“said Ailey, assistant professor of physics and astronomy at Colgate University. “As shown in our recently published PNAS Article We have already found three supermassive dark star candidates while analyzing JWST data for four high-redshift JADES objects Curtis-Lake et alI’m sure we’ll identify more soon.

The idea of ​​dark stars originated in a series of conversations between Freese and Doug Spolier, a graduate student at the University of California, Santa Cruz. They wondered: What was dark matter doing to the first stars that formed in the universe? They then approached Paolo Gondolo, an astronomer at the University of Utah who had joined the team. After several years of development, they Their first paper on this theory was published in the journal Physical Review Letters In 2008.

Freeze, Spolyar, and Gondolo developed a model that suggests that in the centers of early protogalaxies, clouds of hydrogen and helium gas would be accompanied by very dense clumps of dark matter. As the gas cools, it collapses and takes dark matter with it. As the density increases, more and more dark matter particles are annihilated and add more and more heat, preventing gas from collapsing into a dense enough core to support fusion as in a normal star. Instead, it continues to accumulate more gas and dark matter, becoming larger, bloated, and much brighter than normal stars. Unlike normal stars, the energy source is spread out evenly rather than concentrated in the core. With enough dark matter, dark stars can grow to millions of times the mass of our Sun and up to 10 billion times the luminosity of the Sun.

Reference: “Supermassive Dark Star Candidates Seen by JWST” by Cosmin Ailey, Jillian Pollin, and Catherine Freese, 11 July 2023, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2305762120

Funding for this research was provided by the Office of High Energy Physics Program of the US Department of Energy and Vetenskapsradet (Swedish Research Council) at the Oskar Klein Center for Cosmoparticle Physics at Stockholm University.