Acceleration of petaelectronvolt protons in the Galactic Centre
Abstract
Galactic cosmic rays reach energies of at least a few Peta-electronvolts (1 PeV = electron volts). This implies our Galaxy contains PeV accelerators (PeVatrons), but all proposed models of Galactic cosmic-ray accelerators encounter non-trivial difficulties at exactly these energies. Tens of Galactic accelerators capable of accelerating particle to tens of TeV (1 TeV = electron volts) energies were inferred from recent gamma-ray observations. None of the currently known accelerators, however, not even the handful of shell-type supernova remnants commonly believed to supply most Galactic cosmic rays, have shown the characteristic tracers of PeV particles: power-law spectra of gamma rays extending without a cutoff or a spectral break to tens of TeV. Here we report deep gamma-ray observations with arcminute angular resolution of the Galactic Centre regions, which show the expected tracer of the presence of PeV particles within the central 10~parsec of the Galaxy. We argue that the supermassive black hole Sagittarius A* is linked to this PeVatron. Sagittarius A* went through active phases in the past, as demonstrated by X-ray outbursts and an outflow from the Galactic Centre. Although its current rate of particle acceleration is not sufficient to provide a substantial contribution to Galactic cosmic rays, Sagittarius A* could have plausibly been more active over the last years, and therefore should be considered as a viable alternative to supernova remnants as a source of PeV Galactic cosmic rays.
Cite
@article{arxiv.1603.07730,
title = {Acceleration of petaelectronvolt protons in the Galactic Centre},
author = {H. E. S. S. collaboration and : and A. Abramowski and F. Aharonian and F. Ait Benkhali and A. G. Akhperjanian and E. O. Angüner and M. Backes and A. Balzer and Y. Becherini and J. Becker Tjus and D. Berge and S. Bernhard and K. Bernlöhr and E. Birsin and R. Blackwell and M. Böttcher and C. Boisson and J. Bolmont and P. Bordas and J. Bregeon and F. Brun and P. Brun and M. Bryan and T. Bulik and J. Carr and S. Casanova and N. Chakraborty and R. Chalme-Calvet and R. C. G. Chaves and A. Chen and M. Chrétien and S. Colafrancesco and G. Cologna and J. Conrad and C. Couturier and Y. Cui and I. D. Davids and B. Degrange and C. Deil and P. deWilt and A. Djannati-Ataï and W. Domainko and A. Donath and L. O'C. Drury and G. Dubus and K. Dutson and J. Dyks and M. Dyrda and T. Edwards and K. Egberts and P. Eger and J. -P. Ernenwein and P. Espigat and C. Farnier and S. Fegan and F. Feinstein and M. V. Fernandes and D. Fernandez and A. Fiasson and G. Fontaine and A. Förster and M. Füßling and S. Gabici and M. Gajdus and Y. A. Gallant and T. Garrigoux and G. Giavitto and B. Giebels and J. F. Glicenstein and D. Gottschall and A. Goyal and M. -H. Grondin and M. Grudzińska and D. Hadasch and S. Häffner and J. Hahn and J. Hawkes and G. Heinzelmann and G. Henri and G. Hermann and O. Hervet and A. Hillert and J. A. Hinton and W. Hofmann and P. Hofverberg and C. Hoischen and M. Holler and D. Horns and A. Ivascenko and A. Jacholkowska and M. Jamrozy and M. Janiak and F. Jankowsky and I. Jung-Richardt and M. A. Kastendieck and K. Katarzyński and U. Katz and D. Kerszberg and B. Khélifi and M. Kieffer and S. Klepser and D. Klochkov and W. Kluźniak and D. Kolitzus and Nu. Komin and K. Kosack and S. Krakau and F. Krayzel and P. P. Krüger and H. Laffon and G. Lamanna and J. Lau and J. Lefaucheur and V. Lefranc and A. Lemiére and M. Lemoine-Goumard and J. -P. Lenain and T. Lohse and A. Lopatin and C. -C. Lu and R. Lui and V. Marandon and A. Marcowith and C. Mariaud and R. Marx and G. Maurin and N. Maxted and M. Mayer and P. J. Meintjes and U. Menzler and M. Meyer and A. M. W. Mitchell and R. Moderski and M. Mohamed and K. Morå and E. Moulin and T. Murach and M. de Naurois and J. Niemiec and L. Oakes and H. Odaka and S. Öttl and S. Ohm and B. Opitz and M. Ostrowski and I. Oya and M. Panter and R. D. Parsons and M. Paz Arribas and N. W. Pekeur and G. Pelletier and P. -O. Petrucci and B. Peyaud and S. Pita and H. Poon and H. Prokoph and G. Pühlhofer and M. Punch and A. Quirrenbach and S. Raab and I. Reichardt and A. Reimer and O. Reimer and M. Renaud and R. de los Reyes and F. Rieger and C. Romoli and S. Rosier-Lees and G. Rowell and B. Rudak and C. B. Rulten and V. Sahakian and D. Salek and D. A. Sanchez and A. Santangelo and M. Sasaki and R. Schlickeiser and F. Schüssler and A. Schulz and U. Schwanke and S. Schwemmer and A. S. Seyffert and R. Simoni and H. Sol and F. Spanier and G. Spengler and F. Spies and Ł. Stawarz and R. Steenkamp and C. Stegmann and F. Stinzing and K. Stycz and I. Sushch and J. -P. Tavernet and T. Tavernier and A. M. Taylor and R. Terrier and M. Tluczykont and C. Trichard and R. Tuffs and K. Valerius and J. van der Walt and C. van Eldik and B. van Soelen and G. Vasileiadis and J. Veh and C. Venter and A. Viana and P. Vincent and J. Vink and F. Voisin and H. J. Völk and T. Vuillaume and S. J. Wagner and P. Wagner and R. M. Wagner and M. Weidinger and Q. Weitzel and R. White and A. Wierzcholska and P. Willmann and A. Wörnlein and D. Wouters and R. Yang and V. Zabalza and D. Zaborov and M. Zacharias and A. A. Zdziarski and A. Zech and F. Zefi and N. Żywucka},
journal= {arXiv preprint arXiv:1603.07730},
year = {2016}
}
Comments
29 pages, 7 figures, 3 tables, in press, for official published article see http://www.nature.com/nature/journal/v531/n7595/full/nature17147.html