Self-Generated Cosmic-Ray Confinement in TeV Halos: Implications for TeV Gamma-Ray Emission and the Positron Excess

Abstract

Recent observations have detected extended TeV gamma-ray emission surrounding young and middle-aged pulsars. The morphology of these "TeV halos" requires cosmic-ray diffusion to be locally suppressed by a factor of ~100-1000 compared to the typical interstellar medium. No model currently explains this suppression. We show that cosmic-ray self-confinement can significantly inhibit diffusion near pulsars. The steep cosmic-ray gradient generates Alfven waves that resonantly scatter the same cosmic-ray population, suppressing diffusion within ~20 pc of pulsars younger than ~100 kyr. In this model, TeV halos evolve through two phases, a growth phase where Alfven waves are resonantly generated and cosmic-ray diffusion becomes increasingly suppressed, and a subsequent relaxation phase where the diffusion coefficient returns to the standard interstellar value. Intriguingly, cosmic-rays are not strongly confined early in the TeV halo evolution, allowing a significant fraction of injected e+e- to escape. If these e+e- also escape from the surrounding supernova remnant, they would provide a natural explanation for the positron excess observed by PAMELA and AMS-02. Recently created TeV cosmic-rays are confined in the TeV halo, matching observations by HAWC and H.E.S.S. While our default model relaxes too rapidly to explain the confinement of TeV cosmic rays around mature pulsars, such as Geminga, models utilizing a Kraichnan turbulence spectrum experience much slower relaxation. Thus, observations of TeV halos around mature pulsars may provide a probe into our understanding of interstellar turbulence.

10 pages, 3 figures, published on PRD

References in corpus (10)

• The ATNF Pulsar Catalogue
• Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth
• On Pulsar Distance Measurements and their Uncertainties
• A kinetic approach to cosmic ray induced streaming instability at supernova shocks
• High-Energy Gamma Rays from the Milky Way: Three-Dimensional Spatial Models for the Cosmic-Ray and Radiation Field Densities in the Interstellar Medium
• Origin of the Cosmic Ray Galactic Halo Driven by Advected Turbulence and Self-Generated Waves
• Geminga's puzzling pulsar wind nebula
• Constraining the properties of the magnetic turbulence in the Geminga region using HAWC $\gamma$-ray data
• Studying the Milky Way Pulsar Population with Cosmic-Ray Leptons
• Diffuse γ-ray emission from self-confined cosmic rays around Galactic sources

Cited by in corpus (77)

• On the TeV Halo Fraction in gamma-ray bright Pulsar Wind Nebulae
• Detection of a $\gamma$-ray halo around Geminga with the Fermi-LAT and implications for the positron flux
• TeV Halos are Everywhere: Prospects for New Discoveries
• Positron flux and gamma-ray emission from Geminga pulsar and pulsar wind nebula
• Possible origin of the slow-diffusion region around Geminga
• Gamma-ray halos around pulsars as the key to understanding cosmic ray transport in the Galaxy
• Contribution of pulsars to cosmic-ray positrons in light of recent observation of inverse-Compton halos
• Cosmic-Ray Propagation in Light of Recent Observation of Geminga
• Exploring particle escape in supernova remnants through gamma rays
• Evidences of low-diffusion bubbles around Galactic pulsars
• ASTRI Mini-Array Core Science at the Observatorio del Teide
• Cosmic-Ray Diffusion Suppression in Star-forming Regions Inhibits Clump Formation in Gas-rich Galaxies
• Self-Generated Cosmic-Ray Turbulence Can Explain the Morphology of TeV Halos
• Does the Geminga, Monogem and PSR J0622+3749 $\gamma$-ray halos imply slow diffusion around pulsars?
• Gamma rays as probes of cosmic-ray propagation and interactions in galaxies
• Measuring the Local Diffusion Coefficient with H.E.S.S. Observations of Very High-Energy Electrons
• GeV observations of the extended pulsar wind nebulae constrain the pulsar interpretations of the cosmic-ray positron excess
• Constraining the magnetic field in the TeV halo of Geminga with X-ray Observation
• GeV-TeV Cosmic Ray Leptons in the Solar System from the Bow Shock Wind Nebula of the Nearest Millisecond Pulsar J0437-4715
• The Highest Energy HAWC Sources are Likely Leptonic and Powered by Pulsars
• Les Houches Lectures on Indirect Detection of Dark Matter
• A new cosmic ray-driven instability
• Evidence of TeV Halos Around Millisecond Pulsars
• Constraining positron emission from pulsar populations with AMS-02 data
• H.E.S.S. and Suzaku observations of the Vela X pulsar wind nebula
• Dynamical Effects of Cosmic Rays on the Medium Surrounding Their Sources
• The Physics of Pulsar Halos: Research Progress and Prospect
• Cosmic-ray generated bubbles around their sources
• Detection of extended gamma-ray emission around the Geminga pulsar with H.E.S.S
• A pulsar wind nebula origin of the LHAASO-detected UHE gamma-ray sources
• Reanalyze the pulsar scenario to explain the cosmic positron excess considering the recent developments
• Modeling the γ-ray Pulsar Wind Nebulae population in our Galaxy
• Are pulsar halos rare ?
• Anisotropic diffusion cannot explain TeV halo observations
• Population synthesis of pulsar wind nebulae and pulsar halos in the Milky Way -- Predicted contributions to the very-high-energy sky
• The Impact of Cosmic Rays on the Kinematics of the Circumgalactic Medium
• HAWC Detection of a TeV Halo Candidate Surrounding a Radio-quiet pulsar
• TeV halos and the role of pulsar wind nebulae as sources of cosmic ray positrons
• Deciphering Residual Emissions: Time-Dependent Models for the Non-Thermal Interstellar Radiation from the Milky Way
• Millisecond Pulsars Modify the Radio-SFR Correlation in Quiescent Galaxies
• Mirror diffusion of cosmic rays in highly compressible turbulence near supernova remnants
• Ultra-High-Energy Gamma-Ray Astronomy
• Self-consistent interpretations of the multi-wavelength gamma-ray spectrum of LHAASO J0621$+$3755
• Geminga's pulsar halo: an X-ray view
• Evolved Pulsar Wind Nebulae
• Gamma-ray halos around pulsars: impact on pulsar wind physics and galactic cosmic ray transport
• Test of the superdiffusion model in the interstellar medium around the Geminga pulsar
• Prospect of detecting TeV halos with LHAASO: in the framework of the anisotropic diffusion model
• The self-confinement of electrons and positrons from dark matter
• Revisiting GeV-scale annihilating dark matter with the AMS-02 positron fraction
• Interpretation of the puzzling gamma-ray spectrum of the Geminga halo
• Effect of magnetic field correlation length on the gamma-ray pulsar halo morphology under anisotropic diffusion
• Features of the gamma-ray pulsar halo HESS J1831$-$098
• Constraining the slow-diffusion zone size and electron injection spectral index for the Geminga pulsar halo
• Disclosing the catalog pulsars dominating the Galactic positron flux
• Pulsar Wind Nebulae
• A 3D Diffusive and Advective Model of Electron Transport Applied to the Pulsar Wind Nebula HESS J1825-137
• Absence of TeV halos around millisecond pulsars
• Anisotropic Diffusion of $e^{\pm }$ in Pulsar Halos over Multiple Coherence of Magnetic Fields
• The Cherenkov Telescope Array Will Test Whether Pulsars Generate the Galactic Center Gamma-Ray Excess
• Extended TeV Halos May Commonly Exist around Middle-Aged Pulsars
• Detecting and characterizing pulsar haloes with the Cherenkov Telescope Array
• Regions of suppressed diffusion around supernova remnants?
• The environment of TeV halo progenitors
• PHECT: A lightweight computation tool for pulsar halo emission
• Mirage Sources and Large TeV Halo-Pulsar Offsets: Exploring the Parameter Space
• Constraints on the properties of the turbulent magnetic field around Geminga using HAWC measurements
• New estimate for the contribution of the Geminga pulsar to the positron excess
• Self-confinement of relativistic pair beams in magnetized interstellar plasmas: the case of pulsar X-ray filaments
• Investigating the emission signatures of pulsar halo candidate HESS J1813-126
• HAWC Study of the Ultra-High-Energy Spectrum of MGRO J1908+06
• Self-confinement of low-energy cosmic rays around supernova remnants
• Power-law Spectrum of Energetic Particles in Classical Thermal Equilibrium by Pitch-angle Scattering Process
• Morphology of supernova remnants and their halos
• Pulsars in a Bubble? Following Electron Diffusion in the Galaxy with TeV Gamma Rays
• Method for testing diffusive shock acceleration and diffusion propagation of 1-100 TeV cosmic electrons with multiwavelength observations of the Geminga halo and pulsar wind nebula
• The self-control of Cosmic Rays