arXiv subjects

Y. S. Honda

Publications and source records attributed to Y. S. Honda.

5 recordsLinked to original sources

arXiv2026

Distributed accelerators in the jet of Centaurus A: the origin of the spectral hardening of very high energy gamma-rays

We propose the synchrotron self-Compton (SSC) scenario coupled with filamentary jet model, to reproduce the very high energy $γ$-ray emissions from Cen A. With reference to self-similarity of knot-like features in the jet, we assume nonuniform magnetic field associated with current filaments having various transverse sizes. For energetic electron production, the diffusive shock acceleration at sites distributed over the kiloparsec-scale jet is considered. We show that maximum Lorentz factor of the electron steadily exceeds $10^{8}$ due to suppression of synchrotron loss of the electrons trapped in weak magnetic field of the thin filaments, and inhomogeneous SSC in the inner jet can dominantly contribute to establishment of the pronounced hardening of $γ$-ray flux detected by the H.E.S.S. It is also suggested that the spectral contribution from diffuse regions of the outer jet potentially amounts to the observed Fermi fluxes.

astro-ph.HE↗

arXiv2010

Additional Acceleration of Protons and Energetic Neutrino Production in a Filamentary Jet of the Blazar Markarian 501

Blazars have been regarded as one of the most powerful sources of the highest energy cosmic rays and also their byproducts, neutrinos. Provided that a magnetized filamentary system is established in a blazar jet as well, we could apply the mechanism of multi-stage diffusive shock acceleration to a feasible TeV emitter, Mrk 501 to evaluate the achievable maximum energy of protons. Taking conceivable energy restriction into account systematically, it seems adequate to say that EeV-protons are produced at this site by our present model. We also estimate neutrino fluxes generated by these accelerated protons and discuss the detectability based on an updated kilometre-scale telescope such as IceCube.

astro-ph.HE↗

arXiv2005

Effects of mirror reflection versus diffusion anisotropy on particle acceleration in oblique shocks

Cosmic ray particles are more rapidly accelerated in oblique shocks, with the magnetic field inclined with respect to the shock normal direction, than in parallel shocks, as a result of mirror reflection at the shock surface and slower diffusion in the shock normal direction. We investigate quantitatively how these effects contribute to reducing the acceleration time over the whole range of magnetic field inclinations. It is shown that, for quasi-perpendicular inclination, the mirror effect plays a remarkable role in reducing the acceleration time; whereas, at relatively small inclination, the anisotropic diffusion effect is dominant in reducing that time. These results are important for a detailed understanding of the mechanism of particle acceleration by an oblique shock in space and heliosphereic plasmas.

astro-ph↗

arXiv2003

Cosmic-Ray Detection System using Internet

A cosmic ray detection system, consisting of standardized detector stations connected through the Internet, is described. The system can be used for detecting air showers that arrive over a wide area with correlated time. The data at each site are exchanged in (quasi) real time, which makes the system suitable for displaying cosmic ray arrivals at museumns and schools.

astro-ph↗

arXiv2002

Acceleration of Particles by Oblique Shocks and Cosmic Ray Spectra around the Knee Region

We examine the first order Fermi acceleration on the presumption that supernova remnant shocks cross ambient magnetic fields with various angles. These oblique shocks accelerate particles more efficiently than the parallel shocks and elevate the maximum energies achievable by the particles. The primary cosmic ray spectrum is strongly dependent upon these energies. We also consider the dependence of the injection efficiency and of spectral indices on obliquity. When indices and absolute fluxes at $10^{12}$ eV are given for six nuclear groups from balloon-borne data, each energy spectrum develops a smooth rigidity dependent knee structure. The resultant total spectrum also behaves similarly and fits well with ground-based experimental data up to several $10^{17}$ eV. It is shown as well that the chemical composition changes significantly from lighter to heavier nuclei as the energies of particles exceed the knee region. Other predicted curves are compared with the experimental data which they reproduce rather well.

astro-ph↗