A signature of EeV protons of Galactic origin

Tinyakov, P.; Urban, Federico R.; Ivanov, D.; Thomson, G. B.; Tirone, A.H.

doi:10.1093/mnras/stw1163

“…and composition data at all energies (Globus et al 2015b, hereafter G15b), and it is consistent with the anisotropy constraints on galactic protons (Tinyakov et al 2016). …”

Section: Motivationsupporting

confidence: 80%

Probing the Extragalactic Cosmic-Ray Origin with Gamma-Ray and Neutrino Backgrounds

Globus

¹

,

Allard

²

,

Parizot

³

et al. 2017

ApJL

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GeV-TeV gamma-rays and PeV-EeV neutrino backgrounds provide a unique window on the nature of the ultra-high-energy cosmic-rays (UHECRs). We discuss the implications of the recent Fermi-LAT data regarding the extragalactic gamma-ray background (EGB) and related estimates of the contribution of point sources as well as IceCube neutrino data on the origin of the UHECRs. We calculate the diffuse flux of cosmogenic γ-rays and neutrinos produced by the UHECRs and derive constraints on the possible cosmological evolution of UHECR sources. In particular, we show that the mixed-composition scenario considered in Globus et al. (2015b), which is in agreement with both (i) Auger measurements of the energy spectrum and composition up to the highest energies and (ii) the ankle-like feature in the light component detected by KASCADE-Grande, is compatible with both the Fermi-LAT measurements and with current IceCube limits. We also discuss the possibility for future experiments to detect associated cosmogenic neutrinos and further constrain the UHECR models, including possible subdominant UHECR proton sources.

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“…In addition, if galactic cosmic ray sources were concentrated in the disk, and there were many more sources at smaller galactic radii than the galactic radius of the sun, there would be a second anisotropy signal, a relative shortage of events in the direction of the galactic anticenter. For definiteness, in our model [6] we chose the distribution of pulsars. The details of this distribution are not important, as long as the sources are concentrated in the disk and their density is much larger than 1/kpc 3 [6].…”

Section: Introductionmentioning

confidence: 99%

“…For definiteness, in our model [6] we chose the distribution of pulsars. The details of this distribution are not important, as long as the sources are concentrated in the disk and their density is much larger than 1/kpc 3 [6]. For a lower density of sources, our simulations show that an unmistakable anisotropy would result from the sources nearest to the Earth.…”

Section: Introductionmentioning

confidence: 99%

“…To perform these estimates, we traced protons of 10 18.0 -10 18.5 eV through the galactic magnetic field (GMF) to the vicinity of the earth. In galactic coordinates (l,b), the result [6] is that the enhancement in b should be about 20 • in standard deviation, and the deficit centered at l = 140 • should have a standard deviation of about 50 • .…”

Section: Introductionmentioning

confidence: 99%

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Search for EeV protons of galactic origin

Abbasi

¹

,

Abe

²

,

Abu‐Zayyad

³

et al. 2017

Astroparticle Physics

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Cosmic rays in the energy range 10 18.0-10 18.5 eV are thought to have a light, probably protonic, composition. To study their origin one can search for anisotropy in their arrival directions. Extragalactic cosmic rays should be isotropic, but galactic cosmic rays of this type should be seen mostly along the galactic plane, and there should be a shortage of events coming from directions near the galactic anticenter. This is due to the fact that, under the influence of the galactic magnetic field, the transition from ballistic to diffusive behavior is well advanced, and this qualitative picture persists over the whole energy range. Guided by models of the galactic magnetic field that indicate that the enhancement along the galactic plane should have a standard deviation of about 20 • in galactic latitude, and the deficit in the galactic anticenter

show abstract

“…To perform these estimates, we traced protons of 10 18.0 -10 18.5 eV through the galactic magnetic field (GMF) to the vicinity of the earth. In galactic coordinates (l,b), the result [6] is that the enhancement in b should be about 20…”

Section: Introductionmentioning

confidence: 99%

Search for EeV Protons of Galactic Origin

Ivanov¹

2016

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

0

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Cosmic rays in the energy range 10 18.0 -10 18.5 eV are thought to have a light, probably protonic, composition. To study their origin one can search for anisotropy in their arrival directions. Extragalactic cosmic rays should be isotropic, but galactic cosmic rays of this type should be seen mostly along the galactic plane, and there should be a shortage of events coming from directions near the galactic anticenter. This is due to the fact that, under the influence of the galactic magnetic field, the transition from ballistic to diffusive behavior is well advanced, and this qualitative picture persists over the whole energy range. Guided by models of the galactic magnetic field that indicate that the enhancement along the galactic plane should have a standard deviation of about 20• in galactic latitude, and the deficit in the galactic anticenter 2 direction should have a standard deviation of about 50• in galactic longitude, we use the data of the Telescope Array surface detector in 10 18.0 to 10 18.5 eV energy range to search for these effects. The data are isotropic. Neither an enhancement along the galactic plane nor a deficit in the galactic anticenter direction is found. Using these data we place an upper limit on the fraction of EeV cosmic rays of galactic origin at 1.3% at 95% confidence level.

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A signature of EeV protons of Galactic origin

Cited by 14 publications

References 33 publications

Probing the Extragalactic Cosmic-Ray Origin with Gamma-Ray and Neutrino Backgrounds

Probing the Extragalactic Cosmic-Ray Origin with Gamma-Ray and Neutrino Backgrounds

Search for EeV protons of galactic origin

Search for EeV Protons of Galactic Origin

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