The second most distant object ever discovered by the James Webb Telescope may be a “dark star” powered by dark matter rather than nuclear fusion.
By studying the wavelengths of light captured by the James Webb Space Telescope (JWST), researchers identified four dark star candidates. One of them appears to have evidence of “determinant” helium absorption, the researchers reported in a study published in the journal PNAS on September 30th.
First hypothesized in 2007, dark stars are thought to be among some of the first stars (called Population III stars) to form after the Big Bang. According to the theory, they are created when hydrogen and helium, which form black holes on their own, decay and mix with dark matter. Dark stars are extremely large and bright, thought to reach a million times the mass of the Sun and burn a billion times brighter.
“Our original name ‘dark star’ is a misnomer,” Katherine Freese, a physics professor at the University of Texas at Austin who co-authored the study and proposed the dark star hypothesis, told Live Science. “Neither of them were made. [entirely] It is neither dark matter nor dark matter. ”
Finding dark stars could help explain some of the most mysterious objects JWST has discovered in the early universe, such as giant supermassive black holes that formed at incredible speeds, Freeze said. It will also provide insight into the nature of dark matter. “This is an investigation, not just a new kind of star. So these candidates are very encouraging to us,” she said.
To identify potential dark star candidates, the team combed through observations from the JWST Advanced Deep Extragalactic Survey (JADES). They focused on data collected by the Near Infrared Spectrometer (NIRSpec). NIRSpec is an instrument that measures individual wavelengths of light emitted by celestial objects to learn about their temperature, mass, and chemical fingerprint.
The researchers set various criteria in their search. The signal must be no younger than redshift 10 (a redward stretch of the universe’s ancient light, equivalent to 500 million years after the Big Bang), can contain only hydrogen and helium, and must come from a single object.
This resulted in four dark 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 ever observed by JWST.
signal from the first star
Models for each candidate showed that all four were likely dark stars, possibly supermassive dark stars.
The research team also found hints of “definitive evidence” of a supermassive dark star in the JADES-GS-z14-0 wavelength data. This is because a single ionized helium atom absorbs light particles with a wavelength of 1,640 angstroms (an angstrom is 1/100 millionth of a centimeter).
“No other known high-redshift objects are expected to produce such absorption features,” the authors said in their study, adding weight to the suggestion that JADES-GS-z14-0 is a dark star.
But the researchers were surprised to discover that the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile detected JADES-GS-z14-0 emitting oxygen, an element produced only by fusion-powered stars. “That’s a little concerning,” Freeze said.
The research team is currently running simulations to determine how much oxygen a dark star can tolerate before it can no longer form, study co-author Cosmin Illy, a physicist at Colgate University in New York, told Live Science. “Logic tells us that some kind of transition is necessary,” he said.
Dark stars remain controversial and their existence has never been accepted. “The majority of the Pop III star community doesn’t actually think dark matter is a burner.” [dark stars] cosmologist Daniel Whalen of the University of Portsmouth in the UK, who was not involved in the study, told Live Science.
In fact, Whalen said the study’s “big problem” was that it did not distinguish between dark stars and supermassive protostars. “It’s really the elephant in the room here,” he said.
Although dark star candidates are more massive than most supermassive protostars, Whalen explained that wavelength data for both star types must be compared to rule out supermassive protostars.
In response to this criticism, Illy said that supermassive protostars do not live as long as dark stars, so if a large number of suitable signatures are identified, it is statistically more likely to be a dark star. This means that more observations are needed to solve this mystery.
Meanwhile, Freeze said his team is working on automating the search for dark stars in the JWST data, “so you don’t have to do anything except stay awake.”
Source link
