Broadband Photon Spectrum and its Radial Profile of Pulsar Wind Nebulae

Abstract

The observed radial profiles of the X-ray emission from Pulsar Wind Nebulae (PWNe) have been claimed to conflict with the standard one-dimensional (1-D) steady model. However, the 1-D model has not been tested to reproduce both the volume-integrated spectrum and the radial profile of the surface brightness, simultaneously. We revisit the 1-D steady model and apply it to PWNe 3C 58 and G21.5-0.9. We find that the parameters of the pulsar wind, the radius of the termination shock $r_{\mathrm{s}}$ and magnetization $\sigma$, greatly affect both the photon spectrum and radial profile of the emission. We have shown that the parameters constrained by the entire spectrum lead to a smaller X-ray nebula than observed one. We have also tested the case that reproduces only the observations in X and gamma-rays, ignoring the radio and optical components. In this case, there are parameter sets that reproduce both the spectrum and emission profile, but the advection time to the edge of the nebula becomes much smaller than the age. Our detailed discussion clarifies that the standard 1-D steady model has severe difficulty to reproduce both the volume-integrated spectrum and the surface brightness simultaneously. This implies that the model should be improved by taking into account extra physical processes such as spatial diffusion of particles. Additionally, we calculate the surface brightness profile of the radio, optical and TeV gamma-rays. The future observations in these wavelengths are also important to probe the spatial distributions of the relativistic plasma and the magnetic field of PWNe.

15 pages, 10 figures, accepted for publication in ApJ

References in corpus (12)

• Observations of the Crab Nebula with H.E.S.S
• Particle acceleration in relativistic collisionless shocks: Fermi process at last?
• Spitzer Space Telescope Infrared Imaging and Spectroscopy of the Crab Nebula
• Fermi-LAT Search for Pulsar Wind Nebulae around gamma-ray Pulsars
• Broadband X-ray Imaging and Spectroscopy of the Crab Nebula and Pulsar with NuSTAR
• The Distances of SNRs Kes 69 and G21.5-0.9 from HI and 13CO Spectra
• The Expansion and Radio Spectral Index of G21.5-0.9: Is PSR J1833-1034 the Youngest Pulsar?
• The Infrared Detection of the Pulsar Wind Nebula in the Galactic Supernova Remnant 3C 58
• Constraints on particle acceleration sites in the Crab Nebula from relativistic MHD simulations
• NuSTAR study of Hard X-Ray Morphology and Spectroscopy of PWN G21.5-0.9
• Discovery of TeV gamma-ray emission from the pulsar wind nebula 3C 58 by MAGIC
• Hard X-ray observations of PSR J1833-1034 and its associated pulsar wind nebula

Cited by in corpus (10)

• Outflow and Emission Model of Pulsar Wind Nebulae with the Back-reaction of Particle Diffusion
• Hitomi X-ray Observation of the Pulsar Wind Nebula G21.5$-$0.9
• Variability of Late-time Radio Emission in SLSN PTF10hgi
• Confinement of the Crab Nebula with tangled magnetic field by its supernova remnant
• A Comprehensive Study of the Spectral Variation and the Brightness Profile of Young Pulsar Wind Nebulae
• Spectral Break of Energetic Pulsar Wind Nebulae Detected with Wideband X-ray Observations
• Pulsar Wind Nebulae
• Spatio-spectral-temporal Modelling of Two Young Pulsar Wind Nebulae
• Unveiling the nature of the unidentified gamma-ray sources 4FGL J1908.6+0915e, HESS J1907+089/HOTS J1907+091, and 3HWC J1907+085 in the sky region of the magnetar SGR 1900+14
• Particle acceleration to PeV energies in Pulsar Wind Nebula: a two zone model