NASA scientists detect surprise gamma-ray feature beyond our galaxy
World
After obtaining 13 years of data from the Fermi Gamma-ray Space Telescope, a team of astronomers has detected an unusual and as yet unexplained signal outside our galaxy.
"It is a completely serendipitous discovery," said Alexander Kashlinsky, a cosmologist at the University of Maryland and NASA's Goddard Space Flight Centre in Greenbelt. "We found a much stronger signal, and in a different part of the sky, than the one we were looking for."
Astronomers have been searching for a feature of gamma rays associated with the CMB (cosmic microwave background), the oldest light in the Universe. Scientists say the relic radiation originated when the hot expanding Universe cooled enough to form the first atoms, and this event led to the emission of a flash of light that was able to penetrate space for the first time. Stretched by the subsequent expansion of space over the past 13 billion years, this light was first detected as faint microwaves across the sky in 1965.
According to astrophysicist Chris Schrader of the Catholic University of America, the gamma ray peak was detected in the southern part of the sky, far from the CMB, and its intensity was 10 times higher than expected. "While it is not what we were looking for, we suspect it may be related to a similar feature reported for the highest-energy cosmic rays," he emphasised.
Astronomers have been searching for a feature of gamma rays associated with the CMB (cosmic microwave background), the oldest light in the Universe. Scientists say the relic radiation originated when the hot expanding Universe cooled enough to form the first atoms, and this event led to the emission of a flash of light that was able to penetrate space for the first time. Stretched by the subsequent expansion of space over the past 13 billion years, this light was first detected as faint microwaves across the sky in 1965.
According to astrophysicist Chris Schrader of the Catholic University of America, the gamma ray peak was detected in the southern part of the sky, far from the CMB, and its intensity was 10 times higher than expected. "While it is not what we were looking for, we suspect it may be related to a similar feature reported for the highest-energy cosmic rays," he emphasised.
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