Physicists have lower limits on the amount of energy, which may violate Lorentz invariance, then there may occur deviations from the predictions of General relativity. To do this, they analyzed the radiation of gamma-ray burst GRB 190114C: the energy of photons from he reached the teraelectronvolt range, allowing first time scientists to conduct similar calculations for the emission of ultra-high energy. The calculation results were compared with the most stringent to date restrictions. A study published in Physical Review Letters.
In the framework of General relativity is considered that the physical systems possess Lorentz invariance — that is, regulating their behavior, the laws don’t change when moving between inertial frames of reference (mathematically this transition is described by the Lorentz transformations). However, there are models in which it is assumed that Lorentz invariance is fulfilled only approximately and only at a low enough energy — like equations of classical mechanics is well valid only at sufficiently low speeds of the objects. In this case at energies above the characteristic limits are to be observed the effects of violation of Lorentz invariance — in particular, to show the energy dependence of the ratio of energy of photon to its momentum, and with it begins to depend on energy and the velocity of the photon in vacuum.
To test this assumption and to determine the amount of energy which you can trust the predictions of the theory, physicists have experimentally observe the high energy particles. One of the possible sources of such particles — gamma-ray bursts — short (typical duration is few seconds) of the electromagnetic flash, almost daily reported in different areas of space. Within one burst may be released energy in the production of which the Sun would take several billion years, part of this energy reaches us in the form of hard electromagnetic radiation, i.e. high energy photons.
The researchers collaboration MAGIC (Major Atmospheric Gamma Imaging Cherenkov Telescope) with the participation of Luis Nava (Luis Nava) from the National Institute of astrophysics in Italy were searching for the effects of Lorentz-invariance in the emission of a gamma ray burst. Scientists have used observations of the namesake of Cherenkov telescopes at the Observatory Roque de Los Muchachos in the Canary Islands. 14 January 2019, these instruments have detected GRB 190114C first gamma-ray burst, the energy of the photons which reached the teraelectronvolt range (a trillion times the energy of visible light).
Assuming that the analyzed radiation was a violation of Lorentz invariance, the authors attributed the delay in registration at the same time left the source of photons (caused by the difference in their speeds) with the difference in energy of these particles. The process of emission of photons, physicists have described two ways: in the first case — assuming that the source can emit a particle with equal probability at any time from the beginning of the surge, and the second parametrize distribution of photons in time on the basis of the light curve of the flash. The researchers then selected the parameters of the model (which was answered by the typical energy violations of Lorentz invariance in the first and second order) so that the forecasts correspond with the actual measurements.
The researchers found no indications of significant deviations from the predictions of General relativity: selection of parameters did not lead the model to a statistically significant advantage over the null hypothesis (on the conservation of Lorentz invariance). However, physicists have lower limits on the energy scale of such effects at the level of 0.28–0.58 × 1019 GeV for the variations in the first order and 5.6–7.3 × 1010 GeV in the second. It’s not the most rigorous of the currently available borders, but comparable with them within the order of magnitude.
The researchers note that the accuracy of the results was limited by relatively small red shift gamma-ray burst (about 0,4245) — future observations will likely allow us to observe ultrahigh energy photons from the more distant flashes and improve numerical evaluation.
Read more about gamma-ray bursts and their registration can be found in the material “Flash over flash”, and about how scientists first discovered and measured the polarization of radiation in the text “the quick response”.