2024-01-12 11:01:21
Los astronomers they do not come out of their astonishment: “It is a discovery completely fortuitous,” said Alexander Kashlinsky, a cosmologist at the University of Maryland and the Goddard Center for the NASA. “We found a much stronger signal and in a different part of the sky than what we were looking for.”
Curiously, the signal gamma rays It is located in a similar direction and with an almost identical magnitude to another unexplained feature, produced by some of the most energetic cosmic particles ever detected. An article describing the scientific findings has been published in The Astrophysical Journal Letters.
The team of astronomy was looking for a gamma-ray feature related to the CMB (cosmic microwave background), the oldest light in the universe. The scientists They say the CMB originated when the hot, expanding universe cooled enough to form the first atoms, an event that released a burst of light that, for the first time, might permeate the cosmos. Magnified by the subsequent expansion of space over the past 13 billion years, this light was first detected in the form of faint microwaves across the sky in 1965.
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In the 70s, the astronomers They realized that the CMB had a so-called dipole structure, which was later measured with high precision by NASA’s COBE (Cosmic Background Explorer) mission. The CMB is regarding 0.12% hotter, with more microwaves than average, toward the constellation Leo, and colder by the same amount, with fewer microwaves than average, in the opposite direction. To study small temperature variations within the CMB, this signal must be removed. The astronomers The pattern is generally considered to be the result of our own solar system moving relative to the CMB at approximately 370 kilometers per second.
This movement will give rise to a dipole signal in the light from any source astrophysics, but so far the CMB is the only one that has been measured accurately. By looking for the pattern in other forms of light, astronomers might confirm or challenge the idea that the dipole is due entirely to the motion of our solar system.
“This measurement is important because a disagreement with the size and direction of the CMB dipole might give us insight into the physical processes that were operating in the early universe, potentially even when it was less than a billionth of a second old,” he said in a statement. co-author Fernando Atrio-Barandela, professor of theoretical physics at the University of Salamanca.
NASA found an unexpected and still unexplained feature outside our galaxy. (Dpa)
The team reasoned that by adding many years of data from Fermi’s LAT (Large Area Telescope), which scans the entire sky many times a day, a related dipole emission pattern might be detected in the gamma rays. Thanks to the effects of relativity, the dipole of gamma rays should be amplified up to five times more than the CMBs currently detected.
Los scientists combined 13 years of Fermi LAT observations of gamma rays above regarding 3 billion electron volts (GeV); For comparison, visible light has energies between 2 and 3 electron volts. They removed all resolved and identified sources and removed the central plane of our Milky Way to analyze the extragalactic gamma-ray background.
“We found a dipole of gamma raysbut its peak is in the southern sky, far from the CMB, and its magnitude is 10 times larger than we would expect from our motion,” said co-author Chris Shrader, an astrophysicist at the Catholic University of America in Washington and Goddard. .
“While it is not what we were looking for, we suspect it may be related to a similar feature reported for higher energy cosmic rays.”
Cosmic rays are accelerated charged particles, mainly protons and atomic nuclei. The rarest and most energetic particles, called UHECR (ultra-high energy cosmic rays), carry more than a billion times the energy of 3 GeV gamma rays, and their origins remain one of the biggest mysteries in the world. astrophysics.
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Since 2017, the Pierre Auger Observatory in Argentina has informed at NASA of a dipole in the direction of arrival of the UHECR.
Being electrically charged, cosmic rays are deflected by the galaxy’s magnetic field by different amounts depending on their energies, but the UHECR dipole peaks at a location in the sky similar to what Kashlinsky’s team finds in the gamma rays.
And both have strikingly similar magnitudes: regarding 7% more gamma rays or particles than average coming from one direction and correspondingly smaller amounts arriving from the opposite direction.
Los scientists They believe that it is likely that both phenomena are related: that as yet unidentified sources are producing both gamma rays and ultra-high energy particles. To solve this cosmic enigma, the astronomers They must locate these mysterious sources or propose alternative explanations for both features.
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Dpa, TheAstrophysicalJournalLetters, Youtube.
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