Evidences of low-diffusion bubbles around Galactic pulsars

Abstract

Recently, a few-degrees extended $\gamma$-ray halo in the direction of Geminga pulsar has been detected by HAWC, Milagro and Fermi-LAT. These observations can be interpreted with positrons ($e^{+}$) and electrons ($e^{-}$) accelerated by Geminga pulsar wind nebula (PWN), released in a Galactic environment with a low diffusion coefficient ($D_0$), and inverse Compton scattering (ICS) with the interstellar radiation fields. We inspect here how the morphology of the ICS $\gamma$-ray flux depends on the energy, the pulsar age and distance, and the strength and extension of the low-diffusion bubble. In particular we show that $\gamma$-ray experiments with a peak of sensitivity at TeV energies are the most promising ones to detect ICS halos. We perform a study of the sensitivity of HAWC, HESS and the future CTA experiment finding that, with efficiencies of the order of a few %, the first two experiments should have already detected a few tens of ICS halos while the latter will increase the number of detections by a factor of 4. We then consider a sample of sources associated to PWNe and detected in the HESS Galactic plane survey and in the second HAWC catalog. We use the information available in these catalogs for the $\gamma$-ray spatial morphology and flux of these sources to inspect the value of $D_0$ around them and the $e^{\pm }$ injection spectrum. All sources are detected as extended with a $\gamma$-ray emission extended about $15-80$ pc. Assuming that most of the $e^{\pm }$ accelerated by these sources have been released in the interstellar medium, the diffusion coefficient is $2-30\cdot 10^{26}$ cm${}^2$/s at 1 TeV, i.e. two orders of magnitude smaller than the value considered to be the average in the Galaxy. These observations imply that Galactic PWNe have low-diffusion bubbles with a size of at least 80 pc.

21 pages, 11 figures. Phys.Rev.D 101 (2020) 10, 103035

References in corpus (14)

• The ATNF Pulsar Catalogue
• Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth
• Milagro Observations of Multi-TeV Emission from Galactic Sources in the Fermi Bright Source List
• Pulsars versus Dark Matter Interpretation of ATIC/PAMELA
• A Dynamical Model for the Evolution of a Pulsar Wind Nebula inside a Non-Radiative Supernova Remnant
• Galactic electrons and positrons at the Earth:new estimate of the primary and secondary fluxes
• A radiation transfer model for the Milky-Way: I. Radiation fields and application to High Energy Astrophysics
• Inverse Compton Emission from Galactic Supernova Remnants: Effect of the Interstellar Radiation Field
• Absorption of Very High Energy Gamma Rays in the Milky Way
• On the TeV Halo Fraction in gamma-ray bright Pulsar Wind Nebulae
• Cosmic-ray transport from AMS-02 B/C data: benchmark models and interpretation
• Geminga's puzzling pulsar wind nebula
• A Sino-German lambda6 cm polarization survey of the Galactic plane I. Survey strategy and results for the first survey region
• A Cosmic Ray Positron Anisotropy due to Two Middle-Aged, Nearby Pulsars?

Cited by in corpus (42)

• 3HWC: The Third HAWC Catalog of Very-High-Energy Gamma-ray Sources
• Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622 + 3749 Observed by LHAASO-KM2A
• Multimessenger constraints on the dark matter interpretation of the Fermi-LAT Galactic center excess
• 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
• 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
• The Highest Energy HAWC Sources are Likely Leptonic and Powered by Pulsars
• Evidence of TeV Halos Around Millisecond Pulsars
• Constraining positron emission from pulsar populations with AMS-02 data
• The Physics of Pulsar Halos: Research Progress and Prospect
• Cosmic-Ray Positrons Strongly Constrain Leptophilic Dark Matter
• Hadronic vs leptonic models for $\gamma$-ray emission from VER J2227+608
• Modeling the γ-ray Pulsar Wind Nebulae population in our Galaxy
• Anisotropic diffusion cannot explain TeV halo observations
• Are pulsar halos rare ?
• Population synthesis of pulsar wind nebulae and pulsar halos in the Milky Way -- Predicted contributions to the very-high-energy sky
• TeV halos and the role of pulsar wind nebulae as sources of cosmic ray positrons
• Investigating $\gamma$-ray halos around three HAWC bright sources in Fermi-LAT data
• Diffuse Ultra-High-Energy Gamma-Ray Emission From TeV Halos
• Morphology of Gamma-Ray Halos around Middle-Aged Pulsars: Influence of the Pulsar Proper Motion
• Geminga's pulsar halo: an X-ray view
• 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
• Revisiting the Chandra Observation on the Region of PSR J1809-1917: Indication of an X-ray Halo and Implication for the Origin of HESS J1809-193
• Features of the gamma-ray pulsar halo HESS J1831$-$098
• 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
• Extended TeV Halos May Commonly Exist around Middle-Aged Pulsars
• Investigating the Fermi Large Area Telescope sensitivity of detecting the characteristics of the Galactic center excess
• Absence of TeV halos around millisecond pulsars
• Detecting and characterizing pulsar haloes with the Cherenkov Telescope Array
• Cosmic-Ray Convection-Diffusion Anisotropy
• Spatio-spectral-temporal Modelling of Two Young Pulsar Wind Nebulae
• Ultra-high-energy $\gamma$-ray emission associated with the tail of a bow-shock pulsar wind nebula
• Is PSR J0855$-$4644 responsible for the 1.4 TeV electron spectral bump hinted by DAMPE?
• PHECT: A lightweight computation tool for pulsar halo emission
• The traveling-PWN modeling attempt on the enigmatic LHAASO dumbbell-like structure
• Morphology of supernova remnants and their halos