Simulated synchrotron emission from Pulsar Wind Nebulae

Abstract

A complete set of diagnostic tools aimed at producing synthetic synchrotron emissivity, polarization, and spectral index maps from relativistic MHD simulations is presented. As a first application we consider here the case of the emission from Pulsar Wind Nebulae (PWNe). The proposed method is based on the addition, on top of the basic set of MHD equations, of an extra equation describing the evolution of the maximum energy of the emitting particles. This equation takes into account adiabatic and synchrotron losses along streamlines for the distribution of emitting particles and its formulation is such that it is easily implemented in any numerical scheme for relativistic MHD. Application to the axisymmetric simulations of PWNe, analogous to those described by Del Zanna et al. (2004, A&A, 421, 1063), allows direct comparison between the numerical results and observations of the inner structure of the Crab Nebula, and similar objects, in the optical and X-ray bands. We are able to match most of the observed features typical of PWNe, like the equatorial torus and the polar jets, with velocities in the correct range, as well as finer emission details, like arcs, rings and the bright knot, that turn out to arise mainly from Doppler boosting effects. Spectral properties appear to be well reproduced too: detailed spectral index maps are produced for the first time and show softening towards the PWN outer borders, whereas spectral breaks appear in integrated spectra. The emission details are found to strongly depend on both the average wind magnetization (here approximately 2%), and on the magnetic field shape.

14 pages, submitted to A&A

Cited by in corpus (12)

• ECHO: an Eulerian Conservative High Order scheme for general relativistic magnetohydrodynamics and magnetodynamics
• Polarization of the Crab pulsar and nebula as observed by the Integral/IBIS telescope
• Fitting Pulsar Wind Tori. II. Error Analysis and Applications
• Non-thermal emission from relativistic MHD simulations of PWNe: from synchrotron to inverse Compton
• Deep Chandra Observation of the Pulsar Wind Nebula Powered by the Pulsar J1846-0258 in the Supernova Remnant Kes 75
• Optical and infrared observations of the Crab Pulsar and its nearby knot
• PoGOLite - A High Sensitivity Balloon-Borne Soft Gamma-ray Polarimeter
• Rings and Jets around PSR J2021+3651: the `Dragonfly Nebula'
• Effective area calibration of the Reflection Grating Spectrometers of XMM-Newton. I. X-ray spectroscopy of the Crab nebula
• Polarization of the Crab Nebula with disordered magnetic components
• Modeling Pulsar Wind Nebulae
• Polarization in Pulsar Wind Nebulae