The Non-thermal Radiative Properties Of Pulsar Wind Nebulae

Pulsar wind nebulae(PWNe)are one of the sites for the production and radiation of high-energy non-thermal particles in the Universe.A pulsar wind nebula(PWN)is a type of nebula existed inside the shells of supernova remnants(SNRe)that is powered by pulsar winds generated by its central pulsar,observations indicate that the PWN will produce non-thermal photons from radio to TeV bands,and these photons are generally believed to be generated through synchrotron radiation and inverse Compton scattering of the relativistic particles in the PWN.Based on a wealth of information provided by various astronomical equipments,both the productions and non-thermal radiative properties in the PWN are studied in details,and main results are as follows.Non-thermal radiative properties of the Crab nebula were investigated carefully in a one-dimensional spherically symmetric spectral evolution model.For three possible cases of electron's injections,i.e.a relativistic Maxwellian plus a high-energy power-law form(a single electron population),two power-law form and a low-energy power-law plus a relativistic Maxwellian plus a high-energy power-law form(two distinct electron populations),observed multi-band spectra of the Crab nebula are fitted by using the Levenberg-Marquardt method of the x2-minimization procedure.Our results show that the single electron population cannot account for the observed multi-band emission of the Crab nebula,and two distinct electron populations are required although their origins are still under debate.The statistical properties and non-thermal radiation spectra of TeV PWNe were studied in the spherically symmetric spectral evolution model with a broken power-law form injection spectrum.Model calculations of muti-band spectral energy distributions of 18 TeV PWNe indicate that,on the one hand,the indexes of low-energy electron components lie in the range of 1.0-1.8,those of high-energy electron components in the range of 2.1-3.1,and most PWNe are particle-dominated,on the other hand,the ratio of X-ray flux to y-ray flux,Fx/F?,decreases with the PWN age,Fx/F?>10 for young PWNe,1<Fx/F?? 10 for evolved PWNe(except for G292.0+1.8),and Fx/F??1 for mature/old PWNe(except for CTA 1),Statistical analysis for the sample of PWNe further show that(1)electron maximum energy and PWN magnetic field correlate with the magnetic field at the light cylinder,the potential difference at the polar cap,and the spin-down power;(2)the spin-down power positively correlates with radio,X-ray,and bolometric luminosities,but does not correlate with gamma-ray luminosity;(3)the spin-down power positively correlates with radio,X-ray,and gamma-ray band surface brightness;and(4)the PWN radius and the PWN age negatively correlate with X-ray luminosity and the ratio of X-ray to gamma-ray luminosities.A universal relation between the gamma-ray luminosity and power of relativistic outflows are investigated.The relations between the gamma-ray luminosity and power for pulsar wind nebulae(PWNe)and short gamma-ray bursts(SGRBs)are studied,re-spectively,and then these relations are compared with those for well-known relativistic jet system(including long gamma-ray bursts(LGRBs),active galactic nuclei(AGNs),and black hole X-ray binaries(BXBs)).Our results show that there exists a universal correlation between the gamma-ray luminosity and jet power,and the radiation effi-ciency is independent of the gamma-ray luminosity for various relativistic jet systems.Therefore the acceleration and emission mechanisms or efficiencies may be similar in the all relativistic jets regardless of their central engines.