Acceleration of petaelectronvolt protons in the galactic centre - Abramowski, Attila; Becherini, Yvonne; Cologna, Gabriele; Jankowsky, Felix; Mohamed, Mahmoud; Pühlhofer, Gerd; Quirrenbach, Andreas; Schwemmer, Stephanie; Wagner, Stefan; Zacharias, Michael (Nature, 2016)