The obscured universe

Dermer, C. D.

doi:10.1088/1742-6596/120/6/062006

Cited by 4 publications

(2 citation statements)

References 38 publications

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“…Recent claims of a detection of this GZK cutoff (Abbasi et al 2008, Abraham et al 2008 raises the question of how far away these cosmic accelerators must be located in order to present the observed suppression. Besides, simple considerations regarding the coincidence of the GZK and UHECR clustering energies point to the fact that the composition of UHECRs must deviate from pure proton composition and tend to be CNO-like (Dermer 2008), which is favoured by observations (Bellido et al 2009, Unger et al 2009, The Pierre Auger Collaboration 2009a. As CNO nuclei can travel shorter distances as compared to protons, this sets a strong limit on the distance of UHECR sources, without suffering from the large deflection angles by the galactic magnetic field in the case of iron nuclei (Takami & Sato 2009).…”

Section: Introductionmentioning

confidence: 99%

The correlation of UHECRs with nearby galaxies in the Local Volume

Cuesta,

Prada

2009

Preprint

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We explore the possibility of a local origin for ultra high energy cosmic rays (UHECRs). Using the catalogue of Karachentsev et al. including nearby galaxies with distances less than 10Mpc (Local Volume), we search for a correlation with the sample of UHECR events released so far by the Pierre Auger collaboration. The counterpart sample selection is performed with variable distance and luminosity cuts which extract the most likely sources in the catalogue. The probability of chance correlation after penalizing for scans is 0.96%, which corresponds to a correlation signal of 2.6σ. We find that the parameters that maximize the signal are ψ = 3.0 • , D max = 4Mpc and M B = −15 for the maximum angular separation between cosmic rays and galaxy sources, maximum distance to the source, and sources brighter than B-band absolute magnitude respectively. This implies a preference for the UHECRs arrival directions to be correlated with the nearest and most luminous galaxies in the Local Volume, while the angular distance between the cosmic ray events and their possible sources is similar to that found by The Pierre Auger Collaboration using active galactic nuclei (AGNs) within 70-100Mpc instead of local galaxies. We note that nearby galaxies with D < 10Mpc show a similar correlation with UHECRs as compared to well-known particle accelerators such as AGNs, although less than 20% of cosmic ray events are correlated to a source in our study. However, the observational evidence for mixed composition in the high-energy end of the cosmic ray spectrum supports the possibility of a local origin for UHECRs, as CNO nuclei can travel only few Mpc without strong attenuation by the GZK effect, whereas the observed suppression in the energy spectrum would require more distant sources in the case of pure proton composition interacting with the CMB.

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Section: Introductionmentioning

confidence: 99%

The correlation of UHECRs with nearby galaxies in the Local Volume

Cuesta,

Prada

2009

Preprint

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“…If UHECRs are accelerated within Cen B, their chemical composition in a good approximation could be estimated through the photo-disintegration processes and the deviations due to extragalactic and Galactic magnetic fields. The mean free path due to photo-disintegration processes in the δ-function is [50] λ(E, A) 2.5 Mpc…”

Section: Chemical Compositionmentioning

confidence: 99%

Analysis of Fermi-LAT observations, UHECRs and neutrinos from the radio galaxy Centaurus B

Fraija

Araya

Galván-Gaméz

et al. 2019

J. Cosmol. Astropart. Phys.

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Centaurus B (Cen B) is one of the closest and brightest radio-loud galaxy in the southern sky. This radio galaxy, proposed as a plausible candidate for accelerating ultra-high-energy cosmic rays (UHECRs), is near the highest-energy neutrino event reported (IC35) in the High-Energy Starting Events catalog. Pierre Auger observatory reported the highest energy comic rays during 10 years of collecting data with some of them around this source. In this paper, the analysis of the gamma-ray spectrum and the light curve above 200 MeV is presented with nine years of cumulative Fermi-LAT data around Cen B. Taking into consideration the multi-wavelength observations carried out about this radio galaxy, leptonic and hadronic scenarios are introduced in order to fit the spectral energy distribution, assuming that the gamma-ray flux is produced in a region close to the core and in the extended lobes. Using the best-fit values found, several physics properties of this radio galaxy are derived. Furthermore, a statistical analysis of the cosmic ray distribution around Cen B is performed, finding that this distribution is not different from the background at a level of significance of 5%. Considering the UHECR event associated to this source by Moskalenko et al.[1] and extrapolating its luminosity to low energies, we do not find enough evidence to associate the highest-energy neutrino event (IC35) with this radio galaxy.

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On the Possible Association of Ultra High Energy Cosmic Rays With Nearby Active Galaxies

Moskalenko

Stawarz

Porter

et al. 2009

ApJ

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Data collected by the Pierre Auger Observatory (Auger) provide evidence for anisotropy in the arrival directions of cosmic rays (CRs) with energies >57 EeV that suggests a correlation with the positions of active galactic nuclei (AGN) located within ∼75 Mpc and 3.2 • of the arrival directions. This analysis, however, does not take into account AGN morphology. A detailed study of the sample of AGN whose positions are located within 3.2 • of the CR events (and extending our analysis out to ∼150 Mpc) shows that most of them are classified as Seyfert 2 and low-ionization nuclear emission-line region (LINER) galaxies whose properties do not differ substantially from other local AGN of the same types. Therefore, if the production of the highest energy CRs is persistent in nature, i.e., operates in a single object on long ( Myr) timescales, the claimed correlation between the CR events observed by Auger and local active galaxies should be considered as resulting from a chance coincidence. Additionally, most of the selected sources do not show significant jet activity, and hence, in most conservative scenarios, there are no reasons for expecting them to accelerate CRs up to the highest energies, ∼10 20 eV. If the extragalactic magnetic fields and the sources of these CRs are coupled with matter, it is possible that the deflection angle is larger than expected in the case of a uniform source distribution due to effectively larger fields. A future analysis has to take into account AGN morphology and may yield a correlation with a larger deflection angle and/or more distant sources. We further argue that the nearby radio galaxy NGC 5128 (Cen A) alone could be associated with at least 4 events due to its large radio extent, and PKS 1343-60 (Cen B), another nearby radio galaxy, can be associated with more than 1 event due to its proximity to the Galactic plane and, correspondingly, the stronger Galactic magnetic field the ultra high energy CRs (UHECRs) encounter during propagation to the Earth. If the UHECRs associated with these events are indeed accelerated by Cen A and Cen B, their deflection angles may provide information on the structure of the magnetic field in the direction of these putative sources. Future γ-ray observations (by, e.g., Fermi Gamma-ray Space Telescope [Fermi] formerly Gamma-Ray Large Area Space Telescope [GLAST], and High Energy Stereoscopic System [HESS] in the Southern hemisphere) may provide additional clues to the nature of the accelerators of the UHECRs in the local Universe.

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The obscured universe

Cited by 4 publications

References 38 publications

The correlation of UHECRs with nearby galaxies in the Local Volume

The correlation of UHECRs with nearby galaxies in the Local Volume

Analysis of Fermi-LAT observations, UHECRs and neutrinos from the radio galaxy Centaurus B

On the Possible Association of Ultra High Energy Cosmic Rays With Nearby Active Galaxies

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