Einstein’s theory of relativity assumes that the speed of light in vacuum is a constant, independent of the photon or the energy of the photon.
In order to verify this hypothesis, a number of Spanish institutions have participated in MAGIC scientific cooperation and have two telescopes in La Palma to detect very high-energy gamma rays, which used the huge gamma recorded on January 14, 2019 Ray burst data (GRB).
The MAGIC telescope in the Canary Islands detected a huge gamma-ray burst in January 2019 to test whether the speed of light in a vacuum is constant, independent of the energy of the photon
This attempt is based on the fact that Einstein’s theory describes gravity as the result of the interaction between mass and space-time, and his prediction has been confirmed in numerous experiments. Nevertheless, physicists suspect that there is still a more basic theory, that is, the nature of quantum.
Some of the gravitonic theories that have been proposed include the possibility that the speed of photon propagation in a vacuum depends on its energy. This hypothetical phenomenon is called Lorentz invariance violation (LIV).
It is believed that if there is such a speed difference, unless its effects appear in GRB and accumulate over a long period of time, or equivalently, accumulate over a long distance, its speed difference will not be measurable. On Earth.
The most violent explosion in the universe
GRB is a brief flash of high-energy photons from a distant cosmic explosion. The photons produced by these gamma-ray bursts have traveled billions of years before reaching the earth, which may allow the effect of hypothetical differences in their speeds to be measured.
In addition, the theory of quantum gravity predicts that the greater the energy of the photon, the greater the difference. Therefore, extremely high-energy gamma-ray telescopes, such as MAGIC, are expected to be particularly competitive in finding LIV effects.
The photons of different energies emitted 4.5 billion years ago reach the earth in less than one minute, thus limiting the assumption that the speed of these light particles depends on their energy.
GRB occurs at an unpredictable time and place in the sky. There are detectors for these explosives on satellites orbiting the earth. They have a wide field of view, allowing them to detect and locate immediately after the occurrence, and send alarms to telescopes around the world, including MAGIC. , Participate in its observation and research.
On January 14 last year, after receiving an alert from the GRB detector of the Swift satellite, MAGIC completed a 15-year search and detected very high-energy gamma-ray bands (or megaelectron volts) or TeV bands for the first time.
Since the observation starts only 50 seconds after the occurrence of MAGIC, the so-called GRB190114C (this is the so-called huge gamma-ray burst method) can be detected.
Marc Ribó, professor at the University of Barcelona and associate coordinator of MAGIC cooperative physics, pointed out: “The detailed study of GRB190114 shows that it is more or less one of the most positive aspects of GRB. Good news. Because it means that we may find more similar substances. Our discovery has opened a new stage in the search for the LIV effect in the observation of cosmic gamma-ray sources.”
Artist’s views on gamma-ray bursts or GRBs observed by the MAGIC telescope. / Superbossa.com and Alice Donini
So far, scientists hope to use this unique observation to find quantum gravity effects. Initially, they encountered an obstacle: the gamma-ray signal recorded by MAGIC decreased monotonously over time. Although this is interesting information about how GRB is produced, looking for LIV effects is not that interesting.
As Daniel Kerszberg, a postdoctoral scientist at IFAE in Barcelona and one of the main authors of the study, said: “To know whether gamma rays travel at different speeds, we should be able to compare the arrival times of gamma rays emitted by gamma rays. GRB is in At the same time. Since it is impossible to know the precise time of each photon emission, we usually use the instantaneous change of the signal to identify the photons that may be emitted at the same time.”
Theoretical model of following photons
But monotonically decreasing signals lack these changes. Therefore, the researchers used a theoretical model to describe the time evolution of the TeV band emission in the time interval between the onset of the explosion and the MAGIC observation.
Kerszberg added: “In order to find IVL signals in our data, we use two different ways to simulate their time evolution. We want to make sure that we don’t make mistakes when drawing conclusions from this abnormal signal. This is the TeV band GRB. The first signal.”
A careful analysis of the data did not reveal any significant differences in the speed of gamma rays of different energies. This is not to say that such efforts are futile, because MAGIC scientists have managed to limit the possible quantum gravity theory.
The obtained limits of quantum gravity are compatible with existing limits, but they are the first limits obtained by observing the higher-energy emission that occurs in gamma-ray bursts.
Javier Rico, a researcher at IFAE in Barcelona and coordinator of analysis and publications for MAGIC cooperation, said: “GRB190114C occurred 4.5 billion years ago when the earth was still forming. Since then, it has emitted gamma Rays have been propagating in the universe until more than a year ago, we found hundreds of them with the MAGIC telescope. By analyzing them, we can determine that the time spent by different photons in the flight differs by at most about one minute.”
The limits on quantum gravity obtained in this work are compatible with those that have existed so far, and were first obtained by observing the higher-energy emission that occurs in GRB.
Through this groundbreaking research, the MAGIC team laid the starting point for future research to find the measurable effects of space-time quantum properties.
IFAE researchers and MAGIC collaboration spokesperson Oscar Blanch concluded: “We believe that the future TeV band GRB detection will include early emission before monotonic decay. It is expected that it will have a rich space-time structure, which will increase our knowledge of space-time structure. Sensitivity. LIV is effective”.
MAGIC (Main Atmospheric Gamma Imaging Cherenkov) is a system composed of two 17-meter-diameter telescopes located at the El Roque de los Muchachos Observatory (ORM) on the Canary Island of La Palma, Spain, at an altitude of 2,200 meters. These telescopes are designed to detect very high energy gamma rays in the energy range of 30 GeV to over 50 TeV using atmospheric Cherenkov imaging technology. The MAGIC telescope is operated by an international cooperation organization composed of 280 people from 12 countries/regions, including scientists, engineers, technicians and others.
Since the establishment of MAGIC, the Spanish community has been involved. Currently, MAGIC’s members include the Research Center for Energy, Environment and Technology (CIEMAT), the Institute of Astrophysics of the Canary Islands (IAC), the Faisaca Alte Energy Institute (IFAE), the Autonomous University of Barcelona (UAB), Barcelona The Institute of Universe Sciences of the University (UB) and the Complutense University of Madrid (UCM). IEEC participated in the project through researchers from the ICCUB and CERES-UAB departments. In addition, the data center of MAGIC is the Information Center Port (PIC) of IFAE and CIEMAT.
“Through the MAGIC observation of GRB 190114C, it is concluded that the limit of Lorentz invariance is violated.” Magic cooperation. Physics Wright Pastor 125 (2020) https://arxiv.org/abs/2001.09728. Doi: 10.1103 / PhysRevLett.125.021301