&Bullet; physics 14, p62
The DArk Matter Particle Explorer has carried out the most accurate measurements of galactic cosmic rays to date.
For over 5 years the DArk Matter Particle Explorer (DAMPE) has been orbiting the earth and measuring cosmic rays. The team behind the telescope has now analyzed cosmic ray data for 4.5 years and found spectral features that do not match predictions  . While similar features have been suggested in other experiments, DAMPE’s measurements are more precise and cover a wider energy range than any other individual experiment. The results could help researchers uncover the origin of galactic cosmic rays.
Cosmic rays consist mainly of protons and helium ions and presumably emanate from supernovae. On their journey to Earth, the rays are deflected by interstellar magnetic fields, making it difficult to pinpoint their sources. However, the researchers hope that by measuring the energy spectra of cosmic rays, they can extract some information about the supernovae that made them fly and about the structure of our galaxy.
In their analysis, the DAMPE team analyzed the energy spectrum of the detected helium ions. These particles had energies from 70 GeV to 80 TeV, an order of magnitude higher than those detected with the alpha magnetic spectrometer on board the International Space Station (see focus: New data reveal the heavy side of cosmic rays) and 100 times higher than those observed with the PAMELA satellite (see synopsis: solar cycle influences cosmic ray positron). At around 1.3 TeV, the team watched the intensity of the spectrum begin to increase and peak at around 34 TeV. The statistical significance of the finding is 4.3 sigma. Signs of such a bump have been seen before, but the uncertainties in previous data were too great to confirm the presence of the bump. The team says they believe the jerky property could be caused by a nearby supernova, but that remains unconfirmed.
– Katherine Wright
Katherine Wright is the assistant editor of physics.
- F. Alemanno et al., “Measurement of the helium energy spectrum of cosmic rays from 70 GeV to 80 TeV with the space mission DAMPE” Phys. Rev. Lett.126201102 (2021).