Jian-Fu Zhang

The multi-band non-thermal emission from the supernova remnant RX J1713.7−3946

Non-thermal X-rays and very high energy (VHE) y -rays have been detected from the supernova remnant (SNR) RX J1713.7-3946, and the recent observations with the Suzaku satellite clearly reveal a spectral cut-off in the X-ray spectrum, which directly relates to the cut-off of the energy spectrum of the parent electrons. However, whether the origin of the VHE γ-rays from the SNR is hadronic or leptonic is still in debate. We studied the multi-band non-thermal emission from RX J1713.7-3946 based on a semi-analytical approach towards the non-linear shock acceleration process by including the contribution of the accelerated electrons to the non-thermal radiation. The results show that the multi-band observations on RX J1713.7-3946 can be well explained in the model with appropriate parameters, and the TeV γ-rays have hadronic origin, i.e. they are produced via proton-proton interactions as the relativistic protons accelerated by the shock collide with the ambient matter.

ORIGIN OF MULTI-BAND EMISSION FROM THE MICROQUASAR CYGNUS X-1

National Natural Science Foundation of China [11233006, 11363003]; Science and Technology Foundation of Guizhou Province [LKT[2012] 27]; Tongren University [S1224]

Spectrum of a jet-emitting disc: application to the microquasar XTE J1118+480

Under the framework of the magnetized accretion ejection structures, we analyse the energy balance properties, and study the spectral energy distributions (SEDs) of the jet-emitting disc (JED) model for black hole X-ray transients. Various radiative processes are considered, i.e. synchrotron, bremsstrahlung, and their Comptonizations, and external Comptonization of radiation from the outer thin disc. With these cooling terms taken into account, we solve the thermal equilibrium equation self-consistently and find three solutions, of which the cold and the hot solutions are stable. Subsequently, we investigate the theoretical SEDs for these two stable solutions. We find the hot JED model can naturally explain the spectra of the Galactic microquasars in their hard states. As an example, we apply this model to the case of XTE J1118+480.

POTENTIAL GAMMA-RAY EMISSIONS FROM LOW-MASS X-RAY BINARY JETS

By proposing a pure leptonic radiation model, we study the potential gamma-ray emissions from jets of the low-mass X-ray binaries. In this model, the relativistic electrons that are accelerated in the jets are responsible for radiative outputs. Nevertheless, dynamics of jets are dominated by the magnetic and proton-matter kinetic energies. The model involves all kinds of related radiative processes and considers the evolution of relativistic electrons along the jet by numerically solving the kinetic equation. Numerical results show that the spectral energy distributions can extend up to TeV bands, in which synchrotron radiation and synchrotron self-Compton scattering are dominant components. As an example, we apply the model to the low-mass X-ray binary GX 339–4. The results can not only reproduce the currently available observations from GX 339–4, but also predict detectable radiation at GeV and TeV bands by Fermi and CTA telescopes. The future observations with Fermi and CTA canbe used to test our model, which could be employed to distinguish the origin of X-ray emissions. Subject headings: gamma rays: general — radiation mechanisms: non-thermal — stars: individual (GX 339–4) — X-ray: binaries

Polarization Radiation with Turbulent Magnetic Fields from X-Ray Binaries

We study the properties of polarized radiation in turbulent magnetic fields from X-ray binary jets. These turbulent magnetic fields are composed of large- and small-scale configurations, which result in the polarized jitter radiation when the characteristic length of turbulence is less than the non-relativistic Larmor radius. On the contrary, the polarized synchrotron emission occurs, corresponding to a large-scale turbulent environment. We calculate the spectral energy distributions and the degree of polarization for a general microquasar. Numerical results show that turbulent magnetic field configurations can indeed provide a high degree of polarization, which does not mean that a uniform, large-scale magnetic field structure exists. The model is applied to investigate the properties of polarized radiation of black hole X-ray binary Cygnus X--1. Under the constraint of multiband observations of this source, our studies demonstrate that the model can explain the high polarization degree at MeV tail and predict the highly polarized properties at high-energy

Broadband Emission Spectra from the Cygnus X-3 Jet in the Soft Spectral State

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Electron transport with re-acceleration and radiation in the jets of X-ray binaries

-ray region, and that the dominant small-scale turbulent magnetic field plays an important role for explaining the highly polarized observation at hard X-ray/soft

Non-thermal emissions from accreting X-ray binary pulsars

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The Multiwavelength Emission from the gamma-ray Binary LS I+61 303

-ray bands. This model can be tested by polarization observations of upcoming polarimeters at high-energy

High-energy neutrino emission from low-mass microquasars

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