On ultra-high energy cosmic rays: Origin in AGN jets and transport in expanding universe

Птускин, В. С.; Zirakashvili, V. N.

doi:10.1016/j.asr.2011.05.022

Cited by 18 publications

(12 citation statements)

References 47 publications

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“…We can therefore already get to the preliminary conclusion that the cosmic-ray spectrum averaged over the radio luminosity function cannot explain the known UHECR data. This agrees with the earlier finding of Ptuskin et al [92] using an approach similar to ours. We note, however, that their attempt to overcome this problem by distinguishing between FR-I and FR-II radio galaxies and assuming a significantly larger acceleration efficiency for the latter does not reproduce the UHECR spectrum up to the highest energies observed [92,Figs.…”

Section: Continuous Source Function Of Uhecr From Radio Galaxiessupporting

confidence: 94%

Ultra-high-energy cosmic rays from radio galaxies

Eichmann

Rachen

Merten

et al. 2018

J. Cosmol. Astropart. Phys.

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Radio galaxies are intensively discussed as the sources of cosmic rays observed above about 3 × 10 18 eV, called ultra-high energy cosmic rays (UHECRs). We present a first, systematic approach that takes the individual characteristics of these sources into account, as well as the impact of the extragalactic magnetic-field structures up to a distance of 120 Mpc. We use a mixed simulation setup, based on 3D simulations of UHECRs ejected by observed, individual radio galaxies taken out to a distance of 120 Mpc, and on 1D simulations over a continuous source distribution contributing from beyond 120 Mpc. Additionally, we include the ultra-luminous radio galaxy Cygnus A at a distance of about 250 Mpc, as its contribution is so strong that it must be considered as an individual point source. The implementation of the UHECR ejection in our simulation setup, both that of individual radio galaxies and the continuous source function, is based on a detailed consideration of the physics of radio jets and standard first-order Fermi acceleration. This allows to derive the spectrum of ejected UHECR as a function of radio luminosity, and at the same time provides an absolute normalization of the problem involving only a small set of parameters adjustable within narrow constraints.We show that the average contribution of radio galaxies taken over a very large volume cannot explain the observed features of UHECRs measured at Earth. However, we obtain excellent agreement with the spectrum, composition, and arrival-direction distribution of UHECRs measured by the Pierre Auger Observatory, if we assume that most UHECRs observed arise from only two sources: The ultra-luminous radio galaxy Cygnus A, providing a mostly light composition of nuclear species dominating up to about 6 × 10 19 eV, and the nearest radio galaxy Centaurus A, providing a heavy composition dominating above 6 × 10 19 eV.Here we have to assume that extragalactic magnetic fields out to 250 Mpc, which we did not include in the simulation, are able to isotropize the UHECR events at about 8 EeV arriving from Cygnus A. Even in this case, significant anisotropy correlated with Cygnus A and Centaurus A could be present at higher energies, and thus allow for differences in UHECR spectrum and composition between the northern and southern hemispheres. If this scenario can be confirmed, it would also imply that the UHECR flux in our local cosmic environment is significantly above the average throughout the universe.

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Section: Continuous Source Function Of Uhecr From Radio Galaxiessupporting

confidence: 94%

Ultra-high-energy cosmic rays from radio galaxies

Eichmann

Rachen

Merten

et al. 2018

J. Cosmol. Astropart. Phys.

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“…It should be pointed out that the source density may increase with the decreasing of energy of accelerated particles. For example, such a behavior was found in our model of cosmic ray acceleration by the AGN jets with the observed distribution on kinetic energy where more numerous weak jets contribute most to small cosmic ray energies [2]. The experimental indication of this effect was found in [9].…”

Section: Discussionmentioning

confidence: 53%

“…We use the following transport equation for cosmic ray protons and nuclei in the expanding Universe filled with the background electromagnetic radiation (see [2] for detail):…”

Section: Transport Equationsmentioning

confidence: 99%

Determination of source spectra of ultrahigh energy cosmic rays

Rogovaia¹

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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The energy spectra and composition of ultra-high energy cosmic rays are changing in a course of propagation in the expanding Universe filled with background radiation. We use a numerical code for solution of inverse problem for cosmic-ray transport equations that enables the determination of source spectra of different nuclei from the cosmic ray spectra observed at the Earth. The source spectrum is calculated without ad hoc assumptions about its' shape. The spectra of protons and iron nuclei injected from the extragalactic sources are found. The effects of cosmological source evolution and the finite distance to the nearest source are studied. The data from the Auger experiment are used to illustrate the method.

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“…Considering the whole population of radio-galaxies, as e.g. in [9] and assuming that ultra-high energy cosmic rays are heavy nuclei so as to weaken the luminosity constraint, one still derives a large conversion factor. The whole population of radio-galaxies injects ⟨nL⟩ = ∫ dL Ldn/dL ∼ 3 × 10 47 erg/Mpc 3 /yr into the inter-galactic medium [6] but, if the source produces heavy nuclei, it also accelerates protons with a ratio determined by the metallicity, which can be at best solar.…”

Section: General Boundsmentioning

confidence: 99%