Researchers at the University of Delaware are part of a collaboration to study cosmic rays. In addition to the water-filled Cherenkov detector tank, the Pierger Ger Observatory in Argentina has another type of cosmic-ray catcher – a fluorescence detector. In a cosmic-ray air shower the charged particles interact with atmospheric nitrogen, causing it to emit ultraviolet light through a process called fluorescence, which is invisible to the human eye – but not to this optical detector. Credit: University of Delaware
Particles smaller than atoms in the universe explode at the speed of light from almost anywhere, somewhere in the cosmos.
Ultra-high-energy cosmic rays with unprecedented precision – the most powerful of these particles – have been measured with scientific collaboration from the Pierre Gerger Observatory, including researchers at the University of Delaware. In doing so, they have found a “kink” in the energy spectrum that sheds more light on the potential origins of these subatomic astronauts.
The team’s findings are based on an analysis of 215,030 cosmic ray events with gies ranging from 2.5 quintile electron volts (EV) recorded in the past decade by the Pierger Jr Observatory in Argentina. It is the world’s largest observatory for the study of cosmic rays.
The new spectral feature represents more than the points formed on the graph, a kink in the cosmic ray energy radiation spectrum at about 13 quintillion electron volts. An assistant professor at the Bartol Research Institute in the Department of Physics and Astronomy at the university, who was involved in the study with the support of the university, brings humanity one step closer to solving the mysteries of nature’s most energetic particles. Of the Delaware Research Foundation. The research is published in Physical Review Letters And Physics Review d.
In this pre-epidemic photo, UD Professor Frank Schroeder works with colleagues to install a radio antenna at the Cosmic Ray Detector Station of the Pierre Ger Observatory near Malargi, Argentina. Credit: University of Delaware
“Since the discovery of cosmic rays 100 years ago, the question that has long been asked is what accelerates these particles?” Said Schroeder. “Pierre Ojre’s criterion of collaboration provides important clues about what we can exclude as a source. From previous work, we know that acceleration is not in our galaxy. Through this latest analysis, we can proceed to our previous clues that ultra-high-energy Cosmic rays are not only protons of hydrogen, but also a combination of nuclei of heavy elements, and this composition varies with radiation. “
Between “ankle” and “toe”
Schroeder, a contributor to data analysis, and UD postdoctoral researcher Alan Coleman have been members of the Pierre Ger collaboration for many years. UDA collaborated as an organizational member in 2018. This team of observers from more than 400 scientists from 17 countries manages the observer, which occupies an area of 1,200-square miles, about the size of Rhode Island.
An array of cosmic ray detector stations at the Pierre Ger Observatory near Malargi, Argentina. The University of Delaware is a member of an international collaboration that runs the observatory, which includes more than 400 scientists from 17 countries. Credit: University of Delaware
The observatory has more than 1,600 detectors known as water-Cherenkov stations spread across the plains of Pampa Amarila (Yellow Prairie), ignored by 27 fluorescence telescopes. Collectively, these devices emit an ultra-high-energy cosmic ray particle into the atmosphere and provide an indirect assessment of its mass. All of this data – the energy, the mass and the direction from which these extraordinary particles came – gives an important clue about its origin.
Previously, scientists believed that these ultra-high-energy cosmic ray particles were mostly protons of hydrogen, but this latest analysis confirms that the particles contain a mixture of nuclei – heavier than oxygen or helium, for example, like silicon and iron. .
Spread over a curve graph representing the cosmic-ray energy spectrum, you can see a steak and a sharp section between the “ankle” by scientists and the “thumb” between the area known as the starting point of the graph. “
In this pre-epidemic photo, UD Posted dotral researcher Alan Coleman is one of the 1,600 cosmic ray detector stations at the Pierre Gerger Observatory, which stretches over 1,200 square miles of Pampa Amarilla. The corrugated metal at the top, called the scintillator panel, and the circular radio antenna both have sensors for the rays of the universe, while the rectangular antenna is for communication with the central building of the observatory. Credit: University of Delaware
“Coleman, who was on a 20-person team who wrote the computer code and crunched the numbers needed for detailed data analysis,” Coleman said. “It has no special name for us.” “I think we’re running out of parts of the anatomy to tell him,” he joked.
Involved in direct discovery, Coleman modified the cascade of particles that formed cosmic-rays while influencing the atmosphere, in order to estimate icle radiation. He also did a detailed study to make sure that this new opposing point was real and that there was no artifact of the detector. The work of the data group took more than two years.
“Obviously, it’s very slight,” Coleman said of the spectrum kink. “But every time you see a bump like this, it signals that physics is changing and that’s very exciting.”
It is very difficult to determine the set of incoming cosmic rays, Coleman said. But the measurement of collaboration is so strong and accurate that a number of other theoretical models where ultra-high-energy cosmic rays are coming from can now be eliminated, while other paths can be advanced with greater vigor.
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Scientists speculate that the active galactic nucleus may be the source of ultra-high-energy cosmic rays. The active galactic nucleus is a supermassive black hole at the center of the galaxy, showing giant planes of objects escaping into a black hole. The St. ur interest shown here is an example of this galaxy class in our galactic neighborhood less than 20 million light-years from Earth. Credit: University of Delaware
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The flow of cosmic rays depends on their radiation. As high as energy is, it rarely occurs in cosmic rays. However, the larger figure shows that this relationship is not easy. Various features indicate that something is happening at different powers, which are informally referred to by scientists as “knees,” “ankles” and “toes”, with which the Pierger Jar observatory is measured in collaboration with Inset. Shows the measurement in detail. Each feature can be interpreted as a change in the composition of the cosmic rays in the respective rays. Credit: University of Delaware
Active galactic nuclei (AGNs) and Starburst galaxies are now operating as potential sources. While their typical distance is about 100 million light years, some candidates are in 20 million light years.
“If we know what the source is, we can find new details about what’s going on.” What is happening that allows these extremes? These particles may be coming from something we do not even know. “
U.D. Ongoing research by the team focuses on further increasing the measurement accuracy of ultra-high-energy cosmic rays and extending the precise measurement of the cosmic ray spectrum to the following gies. Other experiments would make it better overlap, Schroeder said, such as the cosmic ray measurement of an ice cube at the South Pole – another unique spacecraft observation with great involvement from the University of Delaware.
New data shows that cosmic rays are more complex than expected
a. Ab et al. Features the energy radiation spectrum of cosmic rays above 2.5 × 1018 eV with the help of Pierre J×r Observatory, Physical Review Letters (2020). DOI: 10.1103 / fizrivate.1.11.121106
a. Ab et al. The measurement of the cosmic-ray energy radiation spectrum using the Pierre Gerger Observatory is above 2.5 × 1018 eV. Physical Review d (2020). DOI: 10.1103 / fizri.d.102.062005
Provided by the University of Delaware
Testimonial: New feature found in the energy radiation spectrum of the most powerful particles in the universe (October 16, 2020), from October 16, 2020 https://phys.org/news/2020-10-feature-energy-spectrum-universe-powerful.html
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