Multiband emission from pulsar wind nebulae: a possible injection spectrum

Abstract

Aims. Recent research shows that particles with a spectrum of a relativistic Maxwellian plus a high-energy tail can be accelerated by relativistic collisionless shocks. We investigate the possibility of the high-energy particles with this new spectrum injected into pulsar wind nebulae (PWNe) from the terminate shock based on the study of multiwavelength emission from PWNe. Methods. The dynamics of a supernova remnant (SNR) and multiband nonthermal emission from the PWN inside the remnant are investigated using a dynamical model with electrons/positrons injected with the new spectrum. In this model, the dynamical and radiative evolution of a pulsar wind nebula in a nonradiative supernova remnant can be described self-consistently. Results. This model is applied to the three composite SNRs, G0.9+0.1, MSH 15-52, G338.3-0.0, and the multiband observed emission from the three PWNe is reproduced. Conclusions. Our studies on the three remnants provide evidence of a new spectrum of the particles, which are accelerated by the terminate shock and injected into a PWN.

HESS J1632-478: an energetic relic

“…The nebula magnetic field, size, luminosity and inferred age are in reasonable agreement with the simulations by Fang & Zhang (2010). …”

“…This author, starting from a numerical twodimensional particle in cell simulation, found a spectrum that, at the downstream of the shock front, can be described by a relativistic Maxwellian plus a power-law cut-off high energy tail. Such a model has been recently adopted by Fang & Zhang (2010) to model the broad band SED of a sample of PWNs. We adopt the same analytical model that reads:…”

Multiband nonthermal radiative properties of pulsar wind nebulae

“…Our results give R pwn = 11.21 pc, B pwn ≈ 19 µG, and F X /F γ ∼ 10 with T age = 4000 yr. We note that younger age in previous studies is used; for example, T age ∼ 1600 yr, R pwn = 3.0 pc, and B pwn = 21 µG were obtained by Torres et al (2014), and R pwn = 3.6 pc and B pwn = 19.0 µG by Fang & Zhang (2010a). N 157B has an estimated distance of 48 kpc (Macri et al 2006), and its radius is about 10.6 pc (Lazendic et al 2000), or 3.5 pc (Chen et al 2006), or <94 pc .…”

“…Some of the 18 PWNe have been already investigated (e.g., Fang & Zhang 2010a;Torres et al 2014;Martin et al 2014;Zhu et al 2015;Martin et al 2016). Two important quantities that influence the electron energy loss and photon SED of a PWN are R pwn (t) and B pwn (t).…”

“…Here we focus on the 1D model of the dynamical and radiative evolution of a PWN in a nonradiative supernova remnant (SNR) presented in Gelfand et al (2009). In the frame of the model, the radiative properties during different phases of the PWN evolution 1 http://tevcat.uchicago.edu/ are investigated with a single power-law injection spectrum for the electrons/positrons (Gelfand et al 2009), with the relativistic Maxwellian and a high-energy power-law tail injection spectrum for the electrons/positrons (Fang & Zhang 2010a), and with two possible forms of injected electron spectra: a broken power law and the sum of a power law at low energy, and a relativistic Maxwellian plus a high-energy power-law tail . It has been shown that the broken power-law form for the electron injection is required when the model applies to the Crab nebula .…”