Ultrahigh energy cosmic rays from nearby starburst galaxies

Understand

Ultrahigh energy cosmic rays are the most energetic of any subatomic particles ever observed in nature.

• The quest for their mysterious origin is currently a major scientific challenge.
• Here we explore the possibility that these particles originate from nearby starburst galaxies, a scenario that matches the recent observation by the Telescope Array experiment of a cosmic-ray hotspot above 57~EeV not far from the direction of the starburst galaxy M82.
• Specifically, we study the stochastic propagation in space of ultrahigh energy cosmic rays through the state-of-the-art simulation framework CRPropa~3, taking into account all relevant particle interactions as well as deflections by the intervening magnetic fields.