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Astron. Astrophys. 355, 51-55 (2000)

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On energy spectra of UHE cosmic rays accelerated in supergalactic accretion flows

G. Siemieniec-Oziebo and M. Ostrowski

Obserwatorium Astronomiczne, Uniwersytet Jagielloski, ul. Orla 171, 30-244 Kraków, Poland

Received 19 March 1999 / Accepted 7 December 1999


Some ultra-high energy (UHE) cosmic ray (CR) events may be correlated with the Local Supercluster plane. We consider acceleration of such particles at the large-scale accretion flows of matter towards such plane and/or accretion flows onto galaxy clusters.

The formed shocks and the general compression flow are expected to allow for CR diffusive acceleration of UHE particles. For a simplified flow geometry we consider a stationary acceleration of such CRs and we discuss the influence of model parameters on a particle spectral index. We show that the general convergent flow pattern leads naturally to very flat proton spectra with the phase-space spectral indices [FORMULA], as compared to the `canonical' shock value of 4.0.

Key words: acceleration of particles – accretion – shock waves

Send offprint requests to: G. Siemieniec-Oziebo (grazyna@oa.uj.edu.pl)

© European Southern Observatory (ESO) 2000

Online publication: March 17, 2000