Reconciling cosmic ray diffusion with Galactic magnetic field models

Abstract

We calculate the diffusion coefficients of charged cosmic rays (CR) propagating in regular and turbulent magnetic fields. If the magnetic field is dominated by an isotropic turbulent component, we find that CRs reside too long in the Galactic disc. As a result, CRs overproduce secondary nuclei like boron for any reasonable values of the strength and the coherence length of an isotropic turbulent field. We conclude therefore that the propagation of Galactic CRs has to be strongly anisotropic because of a sufficiently strong regular field and/or of an anisotropy in the turbulent field. As a consequence, the number of sources contributing to the local CR flux is reduced by a factor $\mathcal{O}(100)$ compared to the case of isotropic CR diffusion.

13 pages, 4 figures; v2: extended discussion of (toy) models, 16 pages, 7 figures, to appear in JCAP

References in corpus (9)

• Observation of an anomalous positron abundance in the cosmic radiation
• Cosmic-Ray Proton and Helium Spectra from the First CREAM Flight
• Characterizing Foreground for redshifted 21-cm radiation: 150 MHz GMRT observations
• Charged particle diffusion in isotropic random magnetic fields
• Escape model for Galactic cosmic rays and an early extragalactic transition
• Numerical propagation of high energy cosmic rays in the Galaxy I: technical issues
• Cosmic ray signatures of a 2-3 Myr old local supernova
• Filamentary Diffusion of Cosmic Rays on Small Scales
• Large-Scale Cosmic-Ray Anisotropy as a Probe of Interstellar Turbulence

Cited by in corpus (45)

• Direct Measurement of the Cosmic-Ray Proton Spectrum from 50 GeV to 10 TeV with the Calorimetric Electron Telescope on the International Space Station
• On the TeV Halo Fraction in gamma-ray bright Pulsar Wind Nebulae
• Observation of Spectral Structures in the Flux of Cosmic-Ray Protons from 50 GeV to 60 TeV with the Calorimetric Electron Telescope on the International Space Station
• Cosmic-Ray Driven Outflows to Mpc Scales from $L_{\ast }$ Galaxies
• The Coherent Magnetic Field of the Milky Way
• Novel aspects of cosmic ray diffusion in synthetic magnetic turbulence
• Turbulence-Level Dependence of Cosmic-Ray Parallel Diffusion
• Cosmic Ray Models
• First Predicted Cosmic Ray Spectra, Primary-to-Secondary Ratios, and Ionization Rates from MHD Galaxy Formation Simulations
• Regimes of cosmic-ray diffusion in Galactic turbulence
• Test particle simulations of cosmic rays
• The TeV Cosmic Ray Bump: a Message from Epsilon Indi or Epsilon Eridani Star?
• Anisotropic diffusion cannot explain TeV halo observations
• Vela as the Source of Galactic Cosmic Rays above 100 TeV
• Probing galactic cosmic ray distribution with TeV gamma-ray sky
• Galactic diffuse gamma-ray emission at TeV energy
• LHAASO sensitivity for diffuse gamma-ray signals from the Galaxy
• Pion decay model of TIBET-AS$\gamma$ PeV gamma-ray signal
• Anisotropic cosmic-ray diffusion in isotropic Kolmogorov turbulence
• High-energy neutrinos from cosmic ray interactions in the Local Bubble
• Self-consistent model of extragalactic neutrino flux from evolving blazar population
• The coherent magnetic field of the Milky Way halo, Local Bubble and Fan Region
• Gamma-ray halos around pulsars: impact on pulsar wind physics and galactic cosmic ray transport
• Understanding the phase reversals of Galactic cosmic ray anisotropies
• Galactic halo bubble magnetic fields and UHECR deflections
• No longer ballistic, not yet diffusive--the formation of cosmic ray small-scale anisotropies
• Disclosing the catalog pulsars dominating the Galactic positron flux
• Mirages and Large TeV Halo-Pulsar Offsets from Cosmic Ray Propagation
• Caustic-like Structures in UHECR Flux after Propagation in Turbulent Intergalactic Magnetic Fields
• Mapping large-scale diffuse gamma-ray emission in 10-100 TeV band with Cherenkov telescopes
• Dilaton generation in propagation of magnetic dipole waves of pulsar in a galactic magnetic field
• Cosmic ray acceleration and non-thermal emission from fast luminous optical transient sources
• Anisotropic diffusion and the cosmic ray anisotropy
• Diffusion of relativistic charged particles and field lines in isotropic turbulence: I. Numerical simulations
• Hot spots in the neutrino flux created by cosmic rays from Cygnus and Vela?
• Signatures of anisotropic diffusion around PeVatrons in 100 TeV gamma-ray data
• Leptonic and hadronic models of high-energy nebula around V4641 Sgr
• Diffusion of relativistic charged particles and field lines in isotropic turbulence: II. Analytical models
• Investigating the mysterious nature of 1LHAASO J1740+0948u through deep XMM-Newton observations
• Polarized synchrotron data and the structure of the Galactic magnetic field
• Constraints on the properties of the turbulent magnetic field around Geminga using HAWC measurements
• Constraining the cosmic ray propagation halo thickness using Fermi-LAT observations of high-latitude clouds
• Study of Galactic interactions and propagation properties of ultrahigh energy cosmic rays using the precision spectrum from the Pierre Auger Observatory
• Velocity decorrelation functions of high-energy cosmic rays propagating in magnetic fields
• Direct simulations of very high energy cosmic ray acceleration in 3D MHD model of a compact star cluster