The James Webb telescope may have spotted stars powered by dark matter
The James Webb House Telescope has noticed objects within the early universe that is likely to be a brand new type of star — one powered by darkish matter.
These “darkish stars” are nonetheless hypothetical. Their identification in JWST photos is much from sure. But when any of the three candidates — reported within the July 25 Proceedings of the Nationwide Academy of Sciences — turn into this new kind of star, they may supply a glimpse of star formation within the early universe, trace on the nature of darkish matter and probably clarify the origins of supermassive black holes.
First proposed in 2007 by cosmologist Katherine Freese and colleagues, darkish stars may need been a few of the first forms of stars to type within the universe (SN: 1/1/08). Although darkish stars have but to be noticed, they’re regarded as powered by warmth from darkish matter interactions moderately than by nuclear fusion reactions like within the solar.
Darkish stars “could be very bizarre trying,” says Freese, of the College of Texas at Austin. The hypothetical stars would have shaped from clouds of hydrogen and helium that drew in domestically plentiful darkish matter as they coalesced. Although the true nature of darkish matter isn’t identified — its presence is inferred largely by way of its impact on how stars transfer inside galaxies — it’s doable that darkish matter particles can work together with themselves, annihilating one another once they collide and producing huge quantities of sunshine and warmth (SN: 7/7/22). That warmth would hold the cloud of hydrogen and helium from condensing right into a dense, sizzling core like the celebs that exist immediately.
As a result of the warmth from darkish matter annihilations would hold the gasoline cloud from condensing, darkish stars might develop to gargantuan dimension. Theoretically, darkish stars might be 10 instances as extensive as Earth’s orbit across the solar. They is also tens of millions of instances as large because the solar and shine billions of instances brighter — brilliant sufficient, probably, to be noticed by JWST.
To see if any darkish stars are lurking in knowledge from the orbiting observatory, Freese and colleagues pored over photos from a JWST survey of early galaxies. In such photos, JWST has to date found over 700 objects that will have originated within the first few hundred million years of the universe — the epoch when darkish stars would have emerged (SN: 12/16/22). Mild from these distant objects is stretched, or redshifted, because the universe expands. So Freese and colleagues zeroed in on 4 objects already confirmed to be extremely redshifted, making them a few of the oldest objects seen thus far.
These objects are at present regarded as small galaxies from the universe’s relative infancy. However as a result of they’re so far-off, JWST can’t resolve them effectively sufficient to find out whether or not they’re really galaxies or giant, ultrabright stars, the researchers say.
The workforce ran laptop simulations of how a lot mild a hypothetical darkish star may produce at numerous wavelengths. They in contrast these spectra to mild from photos collected by JWST at completely different wavelengths for every of the 4 objects. JWST knowledge from three of these objects are according to the simulated darkish star patterns, Freese and colleagues report.
Some scientists are skeptical. Recognized forms of stars might additionally create the noticed mild from the three candidates, says Sandro Tacchella, an astrophysicist on the College of Cambridge. And figuring out any of the objects as a darkish star would require that the simulated patterns match effectively to extra detailed spectra, says Brant Robertson, a theoretical astrophysicist on the College of California, Santa Cruz.
If darkish stars had been to be discovered, although, “that will be revolutionary,” says examine coauthor Cosmin Ilie, an astrophysicist at Colgate College in Hamilton, N.Y.
Detecting darkish stars would verify the existence of a darkish matter particle and trace at the way it works (SN: 7/7/22). “Simply having the data that [dark matter] is one thing that would annihilate could be actually, actually highly effective,” says Tracy Slatyer, a theoretical physicist at MIT who was not concerned within the examine. That data might assist scientists search for darkish matter elsewhere within the universe, she says.
Darkish stars might additionally assist clarify the formation of supermassive black holes (SN: 3/16/18). As soon as the darkish matter contained in the star has annihilated itself, the remaining hydrogen and helium — tens of millions of instances the mass of the solar in a comparatively compact area — would collapse in on itself and type a black gap. These black holes might merge over time into black holes like those on the facilities of most galaxies, tens of millions or billions of instances as large because the solar.
Future experiments, like in search of brighter or dimmer mild at sure wavelengths, might assist verify whether or not any of the three objects are darkish stars. Freese additionally expects to seek out extra darkish star candidates in future JWST knowledge, she says. However for now, whether or not darkish stars actually exist stays a thriller.
