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The second most distant object ever noticed by the James Webb telescope could also be a ‘darkish star’ powered by darkish matter reasonably than nuclear fusion.
By wanting on the wavelengths of sunshine picked up by the James Webb Space Telescope (JWST), researchers have recognized 4 darkish star candidates — with one seemingly possessing a “smoking gun” helium absorption signature, the researchers reported in a examine revealed Sept. 30 within the journal PNAS.
“Our initial name ‘dark star’ is a misnomer,” study co-author Katherine Freese, a professor of physics at The University of Texas at Austin who proposed the darkish star speculation, instructed Live Science. “They’re neither made [entirely] of dark matter nor are they dark.”
Finding darkish stars might clarify a number of the very puzzling objects that JWST has noticed within the early universe, such because the large supermassive black holes that fashioned impossibly quick, Freese stated. It would additionally present insights into the character of darkish matter. “It’s a probe, not just a new kind of star,” she stated, “so these candidates are very encouraging to us.”
To spot the potential darkish star candidates, the group trawled by observations from the JWST Advanced Deep Extragalactic Survey (JADES). They centered on knowledge collected by the Near InfraRed Spectrograph (NIRSpec): an instrument measuring the person wavelengths of sunshine coming from celestial objects to study their temperatures, lots and chemical fingerprints.
The researchers set numerous standards of their search: the indicators wanted to be no youthful than redshift 10 (a redward stretching of the universe’s historical gentle comparable to 500 million years after the Big Bang), might solely comprise hydrogen and helium, and needed to be from a single object.
This led them to 4 darkish star candidates: JADES-GS-z11-0, JADES-GS-z13-0, JADES-GS-z14-0 and JADES-GS-z14-1. JADES-GS-z14-0 is the second most distant object noticed by JWST thus far.
Signals from the primary stars
Models of every candidate confirmed that every one 4 might plausibly be darkish stars, maybe even supermassive darkish stars.
The group additionally discovered hints of the “smoking gun signature” for supermassive darkish stars within the JADES-GS-z14-0 wavelength knowledge — singly ionized helium atoms absorbing gentle particles with a wavelength of 1640 angstroms (an angstrom is one hundred-million occasions smaller than a centimeter).
“No other known high redshift objects are expected to produce such an absorption feature,” the authors wrote within the examine, including weight to their suggestion that JADES-GS-z14-0 is a darkish star.
The group had been stunned to find, nonetheless, that the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile had detected JADES-GS-z14-0 emitting oxygen, a component solely produced by nuclear fusion powered stars. “That worries me a little bit,” Freese stated.
The group at the moment are working simulations to find out how a lot oxygen is permitted earlier than a darkish star is now not capable of type, examine co-author Cosmin Ilie, a physicist at Colgate University in New York, instructed Live Science. “Logic tells me that there should be sort of a transition,” he stated.
Dark stars stay controversial and their existence is not at all accepted. “The majority of the Pop III star community actually doesn’t think that dark matter burners [dark stars] can form,” Daniel Whalen, a cosmologist on the University of Portsmouth within the U.Okay. who was not concerned within the analysis, instructed Live Science.
In reality, Whalen stated {that a} “huge issue” with this analysis is that it didn’t differentiate between darkish stars and supermassive primordial stars. “That’s the elephant in the room really here,” he stated.
Although the darkish star candidates are extra huge than most supermassive primordial stars, their wavelength knowledge must be in contrast for each star sorts to rule out supermassive primordial stars, Whalen defined.
In response to this criticism, Ilie stated that as a result of supermassive primordial stars do not reside so long as darkish stars, if many appropriate signatures are recognized they’re statistically extra prone to be darkish stars. That means many extra observations are wanted to settle this thriller.
Meanwhile, Freese stated that the group is engaged on automating the seek for darkish stars within the JWST knowledge “so we don’t have to do anything except keep our eyes open.”
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