Non-thermal emission and spectral evolution properties of G54.1+0.3

Abstract

The multiband photon emission and spectral evolution of G54.1+0.3 are investigated in the framework of leptonic and leptonic–hadronic models. We model the spectral energy distribution (SED) of the pulsar wind nebula (PWN) and find that both the leptonic and leptonic–hadronic models can well reproduce the multiband observations of the nebula with appropriate model parameters. Combining with dynamical evolution of the PWN, we investigate the time evolution of photon SED and radiative luminosity in the X-ray and TeV γ-ray bands of G54.1+0.3. The results indicate that the synchrotron spectrum and radiative luminosity in the X-ray band of the PWN calculated with these two models have obvious differences as the age increases to about 4 kyr, and the largest difference is present at about 40 kyr. The γ-ray luminosity calculated by the leptonic–hadronic model shows that the contribution of TeV photons arising from the decay of neutral pions produced in proton–proton interaction also changes with time and is always important for modifying the TeV γ-ray spectrum of G54.1+0.3 during the evolution of the PWN.

Multiband nonthermal radiative model of pulsar wind nebulae: Study of the effects of advection and diffusion

“…The irregular interaction of particles in the magnetic field will result in diffusion, and it may be argued that the diffusion coefficient κ(t) ∝ 1/B PWN (t) in the PWNe (e.g., Lerche & Schlickeiser 1981). If the diffusion coefficient is chosen to be linearly proportional to the energy, then the functional form of diffusion is similar to Bohm diffusion (e.g., Ren et al 2019). However, the diffusion coefficient may not necessarily scale linearly with energy (e.g., Abeysekara et al 2017;Tang & Piran 2019).…”