Cosmic rays in astrospheres

Abstract

Cosmic rays passing through large astrospheres can be efficiently cooled inside these "cavities" in the interstellar medium. Moreover, the energy spectra of these energetic particles are already modulated in front of the astrospherical bow shocks. We study the cosmic ray flux in and around lambda Cephei as an example for an astrosphere. The large-scale plasma flow is modeled hydrodynamically with radiative cooling. We studied the cosmic ray flux in a stellar wind cavity using a transport model based on stochastic differential equations. The required parameters, most importantly, the elements of the diffusion tensor, are based on the heliospheric parameters. The magnetic field required for the diffusion coefficients is calculated kinematically. We discuss the transport in an astrospheric scenario with varying parameters for the transport coefficients. We show that large stellar wind cavities can act as sinks for the galactic cosmic ray flux and thus can give rise to small-scale anisotropies in the direction to the observer. Small-scale cosmic ray anisotropies can naturally be explained by the modulation of cosmic ray spectra in huge stellar wind cavities.

References in corpus (15)

• Validation of the new Hipparcos reduction
• A new radiative cooling curve based on an up to date plasma emission code
• Observation of an Anisotropy in the Galactic Cosmic Ray arrival direction at 400 TeV with IceCube
• Evidence for an Additional Heat Source in the Warm Ionized Medium of Galaxies
• An Exact Integration Scheme for Radiative Cooling in Hydrodynamical Simulations
• The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed by Herschel. I. Evidence of clumps, multiple arcs, and a linear bar-like structure
• On the absence of wind bow-shocks around OB-runaway stars: probing the physical conditions of the interstellar medium
• Stellar wind bubbles around WR and [WR] stars
• Local Turbulence Simulations for the Multiphase ISM
• MHD Simulation of the Inner-Heliospheric Magnetic Field
• Ionization rates in the heliosheath and in astrosheaths
• Can the magnetic field in the Orion arm inhibit the growth of instabilities in the bow shock of Betelgeuse?
• A novel code for numerical 3-D MHD studies of CME expansion
• Simulating three-dimensional nonthermal high-energy photon emission in colliding-wind binaries
• The impact of thermal gas in AGN jets on the low-frequency emission

Cited by in corpus (12)

• A Hitch-hiker's Guide to Stochastic Differential Equations: Solution Methods for Energetic Particle Transport in Space Physics and Astrophysics
• Time dependence of the electron and positron components of the cosmic radiation measured by the PAMELA experiment between July 2006 and December 2015
• A generalized two-component model of solar wind turbulence and ab initio diffusion mean free paths and drift lengthscales of cosmic rays
• On the Diversity of M-Star Astrospheres and the Role of Galactic Cosmic Rays Within
• MHD-shock structures of astrospheres: $\lambda$ Cephei-like astrospheres
• A New Model Suite to Determine the Influence of Cosmic Rays on (Exo)planetary Atmospheric Biosignatures -- Validation based on Modern Earth
• The CRONOS Code for Astrophysical Magnetohydrodynamics
• Winds in Star Clusters Drive Kolmogorov Turbulence
• Shock structures of astrospheres
• Skymaps of observables of three-dimensional MHD astrosphere models
• Generalized multi-polytropic Rankine-Hugoniot relations and the entropy condition
• Comic ray flux anisotropies caused by astrospheres