Luck and the very latest scientific equipment have enabled scientists to observe a gamma-ray burst beam with a radio telescope and to detect the polarization of radio waves for the first time – bringing us closer to understanding what the strongest Caused explosions of the universe.
Gamma Ray Bursts (GRBs) are the most powerful explosions in the Universe, emitting powerful jets that travel at more than 99.9% of the speed of light through space, as a much more massive star than our Sun at the end of their lives collapses to produce a Black Hole .
When we examine the light of Gamma Ray burst jets as we discover it on its way through space, this is our best hope to understand how these powerful jets will work, but scientists need to be quick position their telescopes and get the best data. The detection of polarized radio waves from a shock beam, made possible by a new generation of advanced radio telescopes, provides new clues to this puzzle.
The light of this special event, known as GRB 190114C and exploded with the power of About 4.5 billion years ago, the TNT of millions of suns reached the Neil Gehrels Swift Observatory of NASA on January 14, 2019.
A quick warning from Swift allowed the research team to observe the Atacama Large Millimeter / Sub-Millimeter Array ( ALMA ) telescope in Chile to observe the eruption just two hours after Swift discovered it. Two hours later, the team was able to observe the GRB from the VLA telescope (Karl G. Jansky Very Large Array) when it became visible in New Mexico, USA.
Scientists have measured for the first time the size of magnetic field fields in a gamma ray collision beam by observing polarized radio waves. Individual patches of ordered magnetic fields in the beam each have random polarization directions. The observed polarization signal is the average of all visible patches (within the white circle) and proportional to the square root of the number of patches we can see, well below the expected value (about 60%). if the field were located entirely within the white region. As the number of visible spots increases, the measured polarization decreases with time.
By combining the measurements of these observatories, the research team was able to determine the structure of the magnetic fields in the jet itself. Radio light is polarized. Depending on the field origin, theories predict different arrangements of magnetic fields in the jet. By capturing radio data, researchers were able to test these theories for the first time with observations from telescopes.
The University of Bath research team, Northwestern University, the Open University of Israel, Harvard University, California State University of Sacramento, the Max Planck Institute in Garching, and the Liverpool John Moores University found that only 0 8% of the jet light were polarized, which meant that the jet's magnetic field was only ordered over relatively small spots – each less than about 1% of the diameter of the jet. Larger patches would have produced more polarized light.
These measurements suggest that magnetic fields in GRB jets play a less structural role than previously thought.
This helps us to narrow down the possible explanations for the causes and forces of these extraordinary phenomena explosions. The study was published in Astrophysical Journal Letters.
The first author Dr. Tanmoy Laskar from the University of Bath's Astrophysics Group said, "We want to understand why some stars produce these extraordinary jets as they die, and how these dying jets are refueled – the fastest known outflows in the universe moving at speeds that are close to those of light and shine together with the incredible luminosity of over a billion suns.
"I was in a taxi on my way to O & # 39; Hare Airport in Chicago after a visit to staff when the outbreak started. The extreme brightness of this event, and the fact that it was instantly visible in Chile, made it a major target for our study, so I immediately contacted ALMA to say that we were watching this, hoping to discover the first radio polarization signal.
"It was a coincidence that the target for observations with both ALMA in Chile and the VLA in New Mexico was well positioned in the sky. Both facilities responded quickly and the weather was excellent. We then spent two months in a careful process to make sure our measurement was real and free from instrumental effects. Everything went well, and that was exciting. "
Dr. Kate Alexander, who led the VLA observations, said: "The VLA's low-frequency data has confirmed that we are seeing the light from the jet itself and not from the jet itself. Jets interacting with their surroundings. "
Dr. Laskar added, "This measurement opens a new window into GRB science and studies of energetic astrophysical jets. We want to understand whether the low level of polarization measured in this event is characteristic of all GRBs, and if so, what this says about the magnetic structures in GRB jets and the role of magnetic fields in powering jets throughout the universe. "
Professor Carole Mundell, director of astrophysics at the University of Bath, added:" The extraordinary sensitivity of ALMA and the rapid response of the telescopes has enabled us for the first time to measure the degree of polarization of fast and accurate microwaves from a GRB. " Afterglow only two hours after the explosion and probe the magnetic fields that are supposed to drive these powerful, ultra-fast outlets.
The research team is planning to search for more GRBs to further solve the puzzles of the largest explosions in the universe.