the Astronomy scientists They do not come out of their amazement: “It is A.” Discovery This is a complete coincidence, said Alexander Kashlinsky, a cosmologist at the University of Maryland and Goddard Cosmology Center. the a pot. “We found a much stronger signal and in a different part of the sky than we were looking for.”
It is strange that the reference Gamma rays It is located in a similar direction and at roughly the same size as another unexplained feature, produced by some of the most energetic cosmic particles ever discovered. An article describing Scientific results It was published in the journal Astrophysical Letters.
a team Astronomy He was looking for a gamma-ray feature associated with the CMB (cosmic microwave background), the oldest light in the universe. the Scientists They say the CMB arose when the hot, expanding universe cooled enough to form the first atoms, an event that unleashed a burst of light that could permeate the universe for the first time. Amplified by the subsequent expansion of space over the past 13 billion years, this light was first detected as faint microwave waves across the sky in 1965.
In the seventies, Astronomy scientists They realized that the CMB has a so-called dipole structure, which was later measured with high precision by NASA's COBE (Cosmic Background Explorer) mission. The CMB is about 0.12% hotter, with more microwaves than average, toward the constellation Leo, and about the same amount cooler, with fewer microwaves than average, in the opposite direction. To study small temperature changes within the CMB, this signal must be removed. the Astronomy scientists This pattern is generally seen as the result of our solar system moving relative to the CMB at about 370 kilometers per second.
This movement will cause a dipole signal to appear in light from any source AstrophysicsBut so far only the CMB has been measured accurately. By looking for the pattern in other forms of light, astronomers can confirm or disprove the idea that the dipole is entirely due to the motion of our solar system.
“This measurement is important because variation with the size and direction of the CMB dipole can give us insight into the physical processes that were at work in the early universe, perhaps even when it was less than a billionth of a second old,” he said. In a statement by co-author Fernando Atrio Barandela, professor of theoretical physics at the University of Salamanca.
The team reasoned that by adding many years of data from Fermi's LAT (Large Area Telescope), which scans the entire sky several times a day, a relevant dipole emission pattern could be detected in the galaxy. Gamma rays. Thanks to the effects of relativity, dipole Gamma rays It should be amplified by up to five times the magnitude of the currently detected CMB.
the Scientists collected 13 years of Fermi LAT observations of gamma rays above about 3 billion electron volts (GeV); For comparison, visible light has energies between 2 and 3 MeV. They removed all identified sources and removed the central plane of our Milky Way Galaxy to analyze the extragalactic gamma-ray background.
“We found a bipolar of Gamma rays“But its peak is in the southern sky, far from the CMB, and its size is 10 times larger than we would expect from our motion,” said co-author Chris Schrader, an astrophysicist at The Catholic University of America in Washington and Goddard. . .
“Although this is not what we were looking for, we suspect that it may be related to a similar feature reported for high-energy cosmic rays.”
Cosmic rays are accelerated charged particles, especially 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 world's biggest mysteries. Astrophysics.
Malargüe Observatory is participating
Since 2017, Pierre Auger Observatory In Argentina reported NASA From the dipole in the direction of UHECR arrival.
Being electrically charged, cosmic rays are deflected by the galaxy's magnetic field in different amounts depending on their energies, but the UHECR dipole peaks at a location in the sky similar to what Kashlinski's team found in the galaxy. Gamma rays.
They both have strikingly similar amounts: about 7% more gamma rays or particles than average come from one direction and correspondingly smaller amounts arrive from the opposite direction.
the Scientists They believe that the two phenomena are likely related: as yet unidentified sources produce gamma rays and particles of very high energy. To solve this cosmic mystery Astronomy scientists They must locate these mysterious sources or propose alternative explanations for both features.
Video: NASA shows Earth from the International Space Station
DPA, TheAstrophysicalJournalLetters, YouTube.
