SN 1987A as a possible source of cosmic rays up to energy 1018 eV by Yakutsk EAS array data

Yakutsk extensive air shower array experiment is the only one which is in operation since 1974, it has the best exposure around 1018eV. It is believed that the balk of cosmic rays up to ∼1017eV originated in supernova remnants. Under certain conditions they can accelerate cosmic rays up to ∼1018eV or even higher. However, there is a lack of an undoubted observational evidence for such idea. Here we show that Yakutsk experiment probably has observed cosmic rays from SN 1987A. We found that before 1996 the intensity of cosmic rays in energy range 1017–1018eV fluctuate near some average value, then it start to increase. The increase of intensity total 45±5%. It is also accompanied by significant changes in cosmic ray composition; it became heavier – iron dominated. In the last 3-4 years it is a trend to return to the initial state. This peculiarities can be explained by the appearance of SN 1987A. If so, then our results demonstrate that supernova remnants can indeed accelerate cosmic rays up to ∼1018e V. This is an important step in understanding the cosmic ray origin problem and reveal the great importance of long-term and multicomponent observations of ultra-high energy cosmic rays.