Ultrahigh energy nuclei in the turbulent Galactic magnetic field

Giacinti, Gwenael; Kachelrieß, M.; Semikoz, D.; Sigl, G.

doi:10.1016/j.astropartphys.2011.07.006

Cited by 59 publications

(61 citation statements)

References 68 publications

(109 reference statements)

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“…This conclusion also appears to be supported by a recent investigation of cosmic ray anisotropies [44].…”

Section: Implications Of the Snr Paradigm For The Transition To Extrasupporting

confidence: 73%

Origin of Galactic Cosmic Rays

Blasi

2013

Nuclear Physics B - Proceedings Supplements

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The origin of the bulk of cosmic rays (CRs) observed at Earth is the topic of a century long investigation, paved with successes and failures. From the energetic point of view, supernova remnants (SNRs) remain the most plausible sources of CRs up to rigidity ∼ 10 6 − 10 7 GV. This confidence somehow resulted in the construction of a paradigm, the so-called SNR paradigm: CRs are accelerated through diffusive shock acceleration in SNRs and propagate diffusively in the Galaxy in an energy dependent way. Qualitative confirmation of the SNR acceleration scenario has recently been provided by gamma ray and X-ray observations. Diffusive propagation in the Galaxy is probed observationally through measurement of the secondary to primary nuclei flux ratios (such as B/C). There are however some weak points in the paradigm, which suggest that we are probably missing some physical ingredients in our models. The theory of diffusive shock acceleration at SNR shocks predicts spectra of accelerated particles which are systematically too hard compared with the ones inferred from gamma ray observations. Moreover, hard injection spectra indirectly imply a steep energy dependence of the diffusion coefficient in the Galaxy, which in turn leads to anisotropy larger than the observed one. Moreover recent measurements of the flux of nuclei suggest that the spectra have a break at rigidity ∼ 200 GV, which does not sit well with the common wisdom in acceleration and propagation. In this paper I will review these new developments and suggest some possible implications.

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“…This conclusion also appears to be supported by a recent investigation of cosmic ray anisotropies [44].…”

Section: Implications Of the Snr Paradigm For The Transition To Extrasupporting

confidence: 73%

Origin of Galactic Cosmic Rays

Blasi

2013

Nuclear Physics B - Proceedings Supplements

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“…Both these models (dip and mixed composition) lead us to expect that Galactic CRs may end in the EeV region (with a composition dominated by heavy nuclei) rather than at the ankle. This conclusion also appears to be supported by a recent investigation of cosmic ray anisotropies [19].…”

Section: The Transition From Galactic To Extra-galactic Cosmic Rayssupporting

confidence: 73%

Theoretical challenges in acceleration and transport of ultra high energy cosmic rays: A review

Blasi

2013

EPJ Web of Conferences

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Abstract. The wealth of data collected in the last few years thanks to the Pierre Auger Observatory and recently to the Telescope Array made the problem of the origin of ultra high energy cosmic rays a genuinely experimental/observational one. The apparently contradictory results provided by these experiments in terms of spectrum, chemical composition and anisotropies do not allow to reach any final conclusions as yet. Here I will discuss some of the theoretical challenges imposed by these data: in particular I will discuss some issues related to the transition from Galactic to extragalactic cosmic rays and how the different models confront our understanding of Galactic cosmic rays in terms of supernova remnants paradigm. I will also discuss the status of theories aiming at describing acceleration of cosmic rays to the highest energies in relativistic shocks and unipolar inductors.

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“…In this section we will restrict our discussion to how the extragalactic magnetic fields could modify the conclusions we reached in the previous section dedicated to the rectilinear regime. We will not discuss the propagation in the Galactic magnetic field but some details on the observations and constraints can be found in [106,108,108,110,105,107], analytical models of the magnetic fields in the Galaxy in [111,112,113] and studies on the propagation of UHECR and the expected consequences on their arrival directions in [111,112,114,113,115,116,117]. We will also not discuss in detail the impact of extragalactic magnetic fields on the expected anisotropies of the UHECR sky.…”

Section: Cosmic Magnetic Fieldsmentioning

confidence: 99%

Extragalactic propagation of ultrahigh energy cosmic-rays

Allard

2012

Astroparticle Physics

126

136

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In this paper we review the extragalactic propagation of ultrahigh energy cosmic-rays (UHECR). We present the different energy loss processes of protons and nuclei, and their expected influence on energy evolution of the UHECR spectrum and composition. We discuss the possible implications of the recent composition analyses provided by the Pierre Auger Observatory. The influence of extragalactic magnetic fields and possible departures from the rectilinear case are also mentioned as well as the production of secondary cosmogenic neutrinos and photons and the constraints their observation would imply for the UHECRs origin. Finally, we conclude by briefly discussing the relevance of a multi messenger approach for solving the mystery of UHECRs.

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Ultrahigh energy nuclei in the turbulent Galactic magnetic field

Cited by 59 publications

References 68 publications

Origin of Galactic Cosmic Rays

Origin of Galactic Cosmic Rays

Theoretical challenges in acceleration and transport of ultra high energy cosmic rays: A review

Extragalactic propagation of ultrahigh energy cosmic-rays

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