Heavy nuclei at the end of the cosmic-ray spectrum?

Anchordoqui, Luis A.; Romero, Gustavo E.; Combi, J. A.

doi:10.1103/physrevd.60.103001

Cited by 95 publications

(123 citation statements)

References 36 publications

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“…As the cavity expands, a strong shock front is formed on the contact surface with the cool interstellar medium. The shock velocity can reach several thousands of kilometers per second and ions like iron nuclei can be efficiently accelerated in this scenario, up to ultrahigh energies, by Fermi's mechanism [317]. If the super-GZK particles are heavy nuclei from outside our Galaxy, then the nearby (∼ 3 Mpc …”

Section: Tev Emission From Qrsmentioning

confidence: 99%

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Astrophysical origins of ultrahigh energy cosmic rays

2004

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In the first part of this review we discuss the basic observational features at the end of the cosmic ray energy spectrum. We also present there the main characteristics of each of the experiments involved in the detection of these particles. We then briefly discuss the status of the chemical composition and the distribution of arrival directions of cosmic rays. After that, we examine the energy losses during propagation, introducing the Greisen-Zaptsepin-Kuzmin (GZK) cutoff, and discuss the level of confidence with which each experiment have detected particles beyond the GZK energy limit. In the second part of the review, we discuss astrophysical environments able to accelerate particles up to such high energies, including active galactic nuclei, large scale galactic wind termination shocks, relativistic jets and hot-spots of Fanaroff-Riley radiogalaxies, pulsars, magnetars, quasar remnants, starbursts, colliding galaxies, and gamma ray burst fireballs. In the third part of the review we provide a brief summary of scenarios which try to explain the super-GZK events with the help of new physics beyond the standard model. In the last section, we give an overview on neutrino telescopes and existing limits on the energy spectrum and discuss some of the prospects for a new (multi-particle) astronomy. Finally, we outline how extraterrestrial neutrino fluxes can be used to probe new physics beyond the electroweak scale. Solicited Review Article Prepared for Reports on Progress in Physics 1 PREFACEReviewing cosmic ray physics is a risky business. Theoretical models continue to appear at an amazing rate, both in the astrophysical and more exotic domains. We warn the reader: we do not (nor we could) intend to make an homogeneous coverage of all the ideas of our fellow colleagues. Reading differently focused reviews on the issue (quoted here along the way) is, in our view, the best approach to such a wide topic of research.2 Contents

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Section: Tev Emission From Qrsmentioning

confidence: 99%

“…The acceleration of particles in starburst galaxies is thought to be a two-stage process [317]. First, ions are thought to be diffusively accelerated at single SNRs within the nuclear region of the galaxy.…”

Section: Two-step Acceleration-process In Starburstsmentioning

confidence: 99%

Astrophysical origins of ultrahigh energy cosmic rays

2004

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“…This poses a challenge to account for the most extreme UHE events like the 3 × 10 20 eV Fly's Eye event [44], if sources are too distant [15]. Candidate nearby sources of heavy nuclei include starburst galaxies [45] and ultra-fast spinning newly-born pulsars [46,47]. Our method provides a tool to distinguish ensemble fluctuations from spectral features of the the average source contribution on a statistical basis.…”

Section: Figmentioning

confidence: 99%

Ensemble fluctuations of the flux and nuclear composition of ultrahigh energy cosmic ray nuclei

2013

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The flux and nuclear composition of ultra-high energy cosmic rays depend on the cosmic distribution of their sources. Data from cosmic ray observatories are yet inconclusive about their exact location or distribution, but provide a measure for the average local density of these emitters. Due to the discreteness of the emitters the flux and nuclear composition is expected to show ensemble fluctuations on top of the statistical variations, i.e. "cosmic variance". This effect is strongest for the most energetic cosmic rays due to the limited propagation distance in the cosmic radiation background and is hence a local phenomenon. For the statistical analysis of cosmic ray emission models it is important to quantify the possible level of this variance. In this paper we present a completely analytic method that describes the variation of the flux and nuclear composition with respect to the local source density. We highlight that proposed future space-based observatories with exposures of O(10 6 km 2 sr yr) will attain sensitivity to observe these spectral fluctuations in the cosmic ray energy spectrum at Earth relative to the overall power-law fit.PACS numbers: 96.50.S-, 98.70.Sa, 13.85.Tp

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“…Such a picture might correspond to that of extended TeV sources without significant correlated emission at low energies like TeV J2032+4130 [24,25,26]. The same mechanism might operate in starburst galaxies where combined effect of the large number massive stars should produce a high density of CRs in a very rich environment [27,28].…”

Section: Collective Effects Of Stellar Winds In Star Forming Regionsmentioning

confidence: 99%

Gamma rays from star-forming regions

Romero¹

2008

AIP Conference Proceedings

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Abstract. Star-forming regions have been tentatively associated with gamma-ray sources since the early days of the COS B satellite. After the Compton Gamma-Ray Observatory, the statistical evidence for such an association has became overwhelming. Recent results from Cherenkov telescopes indicate that some high-energy sources are produced in regions of active star formation like Cygnus OB2 and Westerlund 2. In this paper I will briefly review what kind of stellar objects can produce gamma-ray emission in star-forming regions and I will suggest that the formation process of massive stars could in principle result in the production of observable gamma rays.

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Heavy nuclei at the end of the cosmic-ray spectrum?

Cited by 95 publications

References 36 publications

Astrophysical origins of ultrahigh energy cosmic rays

Astrophysical origins of ultrahigh energy cosmic rays

Ensemble fluctuations of the flux and nuclear composition of ultrahigh energy cosmic ray nuclei

Gamma rays from star-forming regions

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