The Role of Structured Magnetic Fields on Constraining Properties of Transient Sources of Ultra-High-Energy Cosmic Rays

Takami, H.; Murase, Kohta

doi:10.1088/0004-637x/748/1/9

Cited by 26 publications

(24 citation statements)

References 102 publications

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“…A reliable upper limit of the properties originates from the Faraday rotation measurements of polarized radio emission from distant objects, B ffiffiffi ffi l c p ≲ ð1 nGÞ ffiffiffiffiffiffiffiffiffiffiffiffiffi 1 Mpc p [48]. The properties of average extragalactic magnetic fields evaluated from recent numerical simulations, e.g., [49], are B ffiffiffi ffi l c p ∼ 0.3-1.0 nG Mpc 1=2 [50], which is close to the upper limit obtained by Faraday rotation measurements. Figure 5 demonstrates the magnetic horizon effect in UHECR spectra above 10 7 GeV with the recent IceTop spectrum [51] for normalization.…”

Section: B Magnetic Horizonsupporting

confidence: 71%

Bounds on the origin of extragalactic ultrahigh energy cosmic rays from the IceCube neutrino observations

Yoshida

Takami

2014

Phys. Rev. D

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We study general implications of the IceCube observations in the energy range from 10 6 GeV to 10 10 GeV for the origin of extragalactic ultrahigh energy cosmic rays assuming that high energy neutrinos are generated by the photomeson production of protons in the extragalactic universe. The PeV-energy neutrino flux observed by IceCube gives strong bounds on the photomeson-production optical depth of protons in their sources and the intensity of the proton component of extragalactic cosmic rays. The neutrino flux implies that extragalactic cosmic-ray sources should have the optical depth greater than ∼0.01 and contribute to more than a few percent of the observed bulk of cosmic rays at 10 PeV. If the spectrum of cosmic rays from these extragalactic sources extends well beyond 1 EeV, the neutrino flux indicates that extragalactic cosmic rays are dominant in the observed total cosmic-ray flux at 1 EeV and above, favoring the dip transition model of cosmic rays. The cosmic-ray sources are also required to be efficient neutrino emitters with the optical depth close to unity in this case. The highest energy cosmic-ray (∼10 11 GeV) sources should not be strongly evolved with redshift to account for the IceCube observations, suggesting that any cosmic-ray radiation scenarios involving distant powerful astronomical objects with strong cosmological evolution are strongly disfavored. These considerations conclude that none of the known extragalactic astronomical objects can be simultaneously a source of both PeV and trans-EeV energy cosmic rays. We also discuss a possible effect of cosmic-ray propagation in magnetized intergalactic space to the connection between the observed total cosmic-ray flux and neutrino flux.

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Section: B Magnetic Horizonsupporting

confidence: 71%

Bounds on the origin of extragalactic ultrahigh energy cosmic rays from the IceCube neutrino observations

Yoshida

Takami

2014

Phys. Rev. D

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“…While the contribution from HL GRBs does not have to affect the results especially for the steeper luminosity function, the composition change is expected at the highest energies. Another prediction of the two population models by HL GRBs and LL GRBs is the transition of the effective number density of the UHECR sources [100,101].…”

Section: Discussionmentioning

confidence: 99%

Low-luminosity gamma-ray bursts as the sources of ultrahigh-energy cosmic ray nuclei

et al. 2018

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Recent results from the Pierre Auger Collaboration have shown that the composition of ultrahighenergy cosmic rays (UHECRs) becomes gradually heavier with increasing energy. Although gammaray bursts (GRBs) have been promising sources of UHECRs, it is still unclear whether they can account for the Auger results because of their unknown nuclear composition of ejected UHECRs. In this work, we revisit the possibility that low-luminosity GRBs (LL GRBs) act as the sources of UHECR nuclei, and give new predictions based on the intrajet nuclear composition models considering progenitor dependencies. We find that the nuclear component in the jet can be divided into two groups according to the mass fraction of silicon nuclei, Si-free and Si-rich. Motivated by the connection between LL GRBs and transrelativistic supernovae, we also consider the hypernova ejecta composition. Then, we discuss the survivability of UHECR nuclei in the jet base and internal shocks of the jets, and show that it is easier for nuclei to survive for typical LL GRBs. Finally, we numerically propagate UHECR nuclei ejected from LL GRBs with different composition models and compare the resulting spectra and composition to Auger data. Our results show that both the Sirich progenitor and hypernova ejecta models match the Auger data well, while the Si-free progenitor models have more difficulty in fitting the spectrum. We argue that our model is consistent with the newly reported cross correlation between the UHECRs and starburst galaxies, since both LL GRBs and hypernovae are expected to be tracers of the star-formation activity. LL GRBs have also been suggested as the dominant origin of IceCube neutrinos in the PeV range, and the LL GRB origin of UHECRs can be critically tested by near-future multimessenger observations.

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“…We simply note that, leaving the other parameters unchanged, an impulsive source model should give rise to stronger anisotropies than the corresponding continuous source model does, because of the resulting greater effective source power (for the sources contributing to the observed flux at a given time) and the narrower range of energies observed at a given time from a given source (from energy-dependent diffusion effects), and thus the narrower range of angular deflections. Various aspects of transient sources have been discussed in the literature (e.g., Kalli et al 2011;Murase & Takami 2009;Takami & Murase 2012).…”

Section: General Astrophysical Assumptionsmentioning

confidence: 99%

Anisotropy expectations for ultra-high-energy cosmic rays with future high-statistics experiments

d’Orfeuil¹,

Allard²,

Lachaud³

et al. 2014

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Context. Ultra-high-energy cosmic rays (UHECRs) have attracted a lot of attention in astroparticle physics and high-energy astrophysics, due to their challengingly high energies, and to their ability to constrain the physical processes and astrophysical parameters in the most energetic sources of the universe. Despite their very large acceptance, current detectors have failed to detect significant anisotropies in their arrival directions, which had been expected to lead to the long-sought identification of their sources. Some indications about the composition of the UHECRs, which may become heavier at the highest energies, have even called into question the possibility that such a goal could be achieved in the foreseeable future. Aims. We investigate the potential value of a new-generation detector, with an exposure increased by one order of magnitude, to overcome the current situation and make notable progress in detecting anisotropies and thus in the study of UHECRs. We take as an example the expected performances of the JEM-EUSO detector, assuming a uniform full-sky coverage with a total exposure of 300 000 km 2 sr yr. Methods. We simulated realistic UHECR sky maps for a wide range of possible astrophysical scenarios allowed by the current constraints, taking the energy losses and photo-dissociation of the UHE protons and nuclei into account, as well as their deflections by intervening magnetic fields. These sky maps, built for both the expected statistics of JEM-EUSO and the current Pierre Auger Observatory statistics, as a reference, were analysed from the point of view of their intrinsic anisotropies, using the two-point correlation function. A statistical study of the resulting anisotropies was performed for each astrophysical scenario, varying the UHECR source composition and spectrum and the source density and exploring a set of five hundred independent realizations for each choice of a parameter set. Results. We find that significant anisotropies are expected to be detected by a next-generation UHECR detector, for essentially all the astrophysical scenarios studied, and give precise, quantitative meaning to this statement. Conclusions. Our results show that a gain of one order of magnitude in the total exposure of UHECR detectors would make a significant difference compared to the existing experiments, and would allow considerable progress in the study of these mysterious particles and their sources.

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The Role of Structured Magnetic Fields on Constraining Properties of Transient Sources of Ultra-High-Energy Cosmic Rays

Cited by 26 publications

References 102 publications

Bounds on the origin of extragalactic ultrahigh energy cosmic rays from the IceCube neutrino observations

Bounds on the origin of extragalactic ultrahigh energy cosmic rays from the IceCube neutrino observations

Low-luminosity gamma-ray bursts as the sources of ultrahigh-energy cosmic ray nuclei

Anisotropy expectations for ultra-high-energy cosmic rays with future high-statistics experiments

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