High energy photon radiations of gamma-ray bursts(GRBs)and active galactic nuclei(AGNs)are dominated by their jet radiations.We examine whether the synchrotron radiations of jets in BL Lacs,flat spectrum radio quasars...High energy photon radiations of gamma-ray bursts(GRBs)and active galactic nuclei(AGNs)are dominated by their jet radiations.We examine whether the synchrotron radiations of jets in BL Lacs,flat spectrum radio quasars(FSRQs),and Narrow Line Seyfert 1 galaxies(NLS1s)follow the relation between the prompt gamma-ray emission and the initial Lorentz factor(Γ0)of GRBs.It is shown that the AGN sample does not agree with the Lp-Ep,z-Γ0 relation of GRBs.In addition,we obtain a tight relation of Lsyn∝Е0.45±0.15δ3.50±0.25 syn,p for FSRQs and NLS1 galaxies,where Lsyn is the luminosity at peak photon energy Esyn,p of the synchrotron radiations.This relation is different from the Lp-Ep,z-Γ0 relation of GRB s.The dependence of Lsyn toδis consistent with the expectation of the Doppler boosting effect for the FSRQs and NLS1 galaxies,but it is not for GRBs.We argue thatΓ0 may be a representative of the kinetic power of the radiating region and the tight Lp-Ep,z-Γ0 relation is shaped by the radiation physics and the jet power together.展开更多
Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and inhomogeneous distribution of GRBs detected by BASTE) that they are locat...Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and inhomogeneous distribution of GRBs detected by BASTE) that they are located at cosmological distances, makes them the most energetic events ever known. For example, the observed radiation energies of some GRBs are equivalent to the total convertion into radiation of the mass energy of more than one solar mass. This is thousand times stronger than the energy of a supernova explosion. Some unconventional energy mechanism and extremely high conversion efficiency for these mysterious events are required. The discovery of host galaxies and association with supernovae at cosmological distances by the recently launched satellite of BeppoSAX and ground based radio and optical telescopes in GRB afterglow provides further support to the cosmological origin of GRBs and put strong constraints on their central engine. It is the aim of this article to review the possible central engines, energy mechanisms, dynamical and spectral evolution of GRBs, especially focusing on the afterglows in multi-wavebands.展开更多
The model proposes that Nuclei of all macroobjects (Galaxy clusters, Galaxies, Star clusters, Extrasolar systems) are made up of Dark Matter Particles (DMP). These Nuclei are surrounded by Shells composed of both Dark...The model proposes that Nuclei of all macroobjects (Galaxy clusters, Galaxies, Star clusters, Extrasolar systems) are made up of Dark Matter Particles (DMP). These Nuclei are surrounded by Shells composed of both Dark and Baryonic matter. This model is used to explain various astrophysical phenomena: Multi-wavelength Pulsars;Binary Millisecond Pulsars;Gamma-Ray Bursts;Fast Radio Bursts;Young Stellar Object Dippers;Starburst Galaxies;Gravitational Waves. New types of Fermi Compact Stars made of DMP are introduced: Neutralino star, WIMP star, and DIRAC star. Gamma-Ray Pulsars are rotating Neutralino and WIMP stars. Merger of binary DIRAC stars can be a source of Gravitational waves.展开更多
We calculate the high energy afterglow emission from short Gamma-Ray Bursts(SGRBs) in the external shock model.There are two possible components contributing to the high energy afterglow:electron synchrotron emission ...We calculate the high energy afterglow emission from short Gamma-Ray Bursts(SGRBs) in the external shock model.There are two possible components contributing to the high energy afterglow:electron synchrotron emission and synchrotron self-Compton(SSC) emission.We find that for typical parameter values of SGRBs,the early high-energy afterglow emission in 10 MeV-10 GeV is dominated by synchrotron emission.For a burst occurring at redshift z = 0.1,the high-energy emission can be detectable by Fermi LAT if the blast wave has energy E ≥ 1051 ergs and the fraction of electron energy εe≥ 0.1.This provides a possible explanation for the high energy tail of SGRB 081024B.展开更多
基金the National Natural Science Foundation of China(Grant Nos.11533003,11851304 and U1731239)Guangxi Science Foundation and special funding for Guangxi distinguished professors(2017AD22006)。
文摘High energy photon radiations of gamma-ray bursts(GRBs)and active galactic nuclei(AGNs)are dominated by their jet radiations.We examine whether the synchrotron radiations of jets in BL Lacs,flat spectrum radio quasars(FSRQs),and Narrow Line Seyfert 1 galaxies(NLS1s)follow the relation between the prompt gamma-ray emission and the initial Lorentz factor(Γ0)of GRBs.It is shown that the AGN sample does not agree with the Lp-Ep,z-Γ0 relation of GRBs.In addition,we obtain a tight relation of Lsyn∝Е0.45±0.15δ3.50±0.25 syn,p for FSRQs and NLS1 galaxies,where Lsyn is the luminosity at peak photon energy Esyn,p of the synchrotron radiations.This relation is different from the Lp-Ep,z-Γ0 relation of GRB s.The dependence of Lsyn toδis consistent with the expectation of the Doppler boosting effect for the FSRQs and NLS1 galaxies,but it is not for GRBs.We argue thatΓ0 may be a representative of the kinetic power of the radiating region and the tight Lp-Ep,z-Γ0 relation is shaped by the radiation physics and the jet power together.
基金a RGC grant of the Hong Kong Government and the National Natural Science Foundation of China.
文摘Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and inhomogeneous distribution of GRBs detected by BASTE) that they are located at cosmological distances, makes them the most energetic events ever known. For example, the observed radiation energies of some GRBs are equivalent to the total convertion into radiation of the mass energy of more than one solar mass. This is thousand times stronger than the energy of a supernova explosion. Some unconventional energy mechanism and extremely high conversion efficiency for these mysterious events are required. The discovery of host galaxies and association with supernovae at cosmological distances by the recently launched satellite of BeppoSAX and ground based radio and optical telescopes in GRB afterglow provides further support to the cosmological origin of GRBs and put strong constraints on their central engine. It is the aim of this article to review the possible central engines, energy mechanisms, dynamical and spectral evolution of GRBs, especially focusing on the afterglows in multi-wavebands.
文摘The model proposes that Nuclei of all macroobjects (Galaxy clusters, Galaxies, Star clusters, Extrasolar systems) are made up of Dark Matter Particles (DMP). These Nuclei are surrounded by Shells composed of both Dark and Baryonic matter. This model is used to explain various astrophysical phenomena: Multi-wavelength Pulsars;Binary Millisecond Pulsars;Gamma-Ray Bursts;Fast Radio Bursts;Young Stellar Object Dippers;Starburst Galaxies;Gravitational Waves. New types of Fermi Compact Stars made of DMP are introduced: Neutralino star, WIMP star, and DIRAC star. Gamma-Ray Pulsars are rotating Neutralino and WIMP stars. Merger of binary DIRAC stars can be a source of Gravitational waves.
基金supported by the National Basic Research Program of China (Grant No. 2009CB824800)the Foundation for the Authors of National Excellent Doctoral Dissertations of Chinathe Qing Lan Project and the NCET Grant
文摘We calculate the high energy afterglow emission from short Gamma-Ray Bursts(SGRBs) in the external shock model.There are two possible components contributing to the high energy afterglow:electron synchrotron emission and synchrotron self-Compton(SSC) emission.We find that for typical parameter values of SGRBs,the early high-energy afterglow emission in 10 MeV-10 GeV is dominated by synchrotron emission.For a burst occurring at redshift z = 0.1,the high-energy emission can be detectable by Fermi LAT if the blast wave has energy E ≥ 1051 ergs and the fraction of electron energy εe≥ 0.1.This provides a possible explanation for the high energy tail of SGRB 081024B.
