Simultaneous Fitting of the Spectral Energy Density, Energy-dependent Size, and X-ray Spectral Index vs. Radius of The Young Pulsar Wind Nebula PWN G0.9+0.1

TL;DR

This paper develops a spherical, spatially-dependent model for young pulsar wind nebulae that simultaneously fits spectral energy distribution, nebular size, and X-ray spectral index, using MCMC to constrain physical parameters.

Contribution

It introduces a comprehensive, multi-parameter fitting approach for PWN emission models that integrates spectral, size, and spectral index data with MCMC for parameter estimation.

Findings

Successfully applied the model to PWN G0.9+0.1.

Constrained nebular magnetic field and particle transport properties.

Enhanced interpretation of future CTA observations.

Abstract

We have constructed and calibrated a spherically-symmetric, spatially-dependent particle transport and emission code for young pulsar wind nebulae (PWNe). This code predicts the spectral energy distribution (SED) of the radiation spectrum at different positions in a PWN, thus yielding the surface brightness vs. radius and hence the nebular size as function of energy. It also predicts the X-ray spectral index at different radii from the central pulsar, depending on the nebular B-field profile and particle transport properties. We apply the code to PWN G0.9+0.1 and fit these three functions concurrently, thus maximizing the constraining power of the data. We use a Markov-chain-Monte-Carlo (MCMC) method to find best-fit parameters with accompanying errors. This approach should allow us to better probe the spatial behaviour of the bulk-particle motion, the $B$-field and diffusion coefficient, and break degeneracies between different model parameters. Our model will contribute to interpreting results by the future Cherenkov Telescope Array (CTA) that will yield many more discoveries plus morphological details of very-high-energy Galactic PWNe.