Status: 16.01.2024, 13:37 PM
By: Tanja Banner
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Artist's impression: The entire sky in gamma rays. The orange-red stripe is the band of the Milky Way. The pink circles show the region in the sky where the mysterious signal was discovered. © NASA's Goddard Space Flight Center
The gamma-ray telescope "Fermi" detects a signal in space that poses a huge puzzle for researchers. Where does it come from?
Greenbelt – While analysing data from the Fermi gamma-ray space telescope, a team of researchers has made a surprising discovery: an "unexpected and previously unexplained signal outside our Milky Way". This is what the Goddard Space Flight Center of the US space agency Nasa writes in a statement. "It's a completely accidental discovery," says cosmologist Alexander Kashlinsky of the Goddard Space Flight Center. "We found a much stronger signal than we were looking for. It's coming from a different part of heaven than the one we've been looking for."
Kashlinsky's research team had actually wanted to use the data from the Fermi gamma-ray telescope to further investigate the cosmic background radiation. In the process, the scientists came across the mysterious gamma-ray signal from a completely different direction. The study was published in The Astrophysical Journal Letters.
Unexpected signal from the universe baffles researchers
"We found a gamma-ray dipole, but its tip is in the southern sky, far from the cosmic background radiation, and its strength is ten times greater than what we would expect based on our motion," explains co-author and astrophysicist Chris Shrader of Goddard Space Flight Center.
The accidentally discovered signal becomes even stranger when you consider that it is close to another, as yet unexplained mystery. The source of some of the oldest cosmic particles ever discovered has also been located in this direction. The origin of the so-called UHECRs (ultra-high-energy cosmic rays) is still a mystery in astrophysics.
What's behind the unidentified signal from space?
Although the signal isn't what they were looking for, "we suspect it's related to a similar feature reported for the highest-energy cosmic rays," Shrader says. Could a previously unidentified source cause both the gamma rays and the ultra-high-energy cosmic rays? To solve the cosmic mystery, either the source of the gamma-ray signal and high-energy radiation must be found, or science must find new explanations for the phenomena. Until then, the mystery remains. (tab)