The detection of very high energy γ-ray emission from the Galactic center has been reported by four independent groups. One of these γ-ray sources,the 10 TeV γ-ray radiation reported by HESS,has been suggested as having a hadronic origin when relativistic protons are injected into and interact with the dense ambient gas. Assuming that such relativistic protons required by the hadronic model come from the tidal disruption of a star by the massive black hole of Sgr A*,we explore the spectrum of the relativistic protons. In the calculations,we investigate cases where different types of stars are tidally disrupted by the black hole of Sgr A*,and we consider that different diffusion mechanisms are used for the propagation of protons. The initial energy distribution of the injected spectrum of protons is assumed to follow a power-law with an exponential cut-off,and we derive the different indices of the injected spectra for the tidal disruption of different types of stars. For the best fit to the spectrum of photons detected by HESS, the spectral index of the injected relativistic protons is about 2.05 when a red giant is tidally disrupted by the black hole of Sgr Aand the diffusion mechanism is the Effective Confinement of Protons.
In this paper,we critically assess GRB080503,a short gamma-ray burst with very bright extended emission(about 30 times the gamma-ray fluence of the initial spike).The light curve of the prompt γ-ray emission of GRB080503 resembles that of GRB 060614 which has been suggested to be due to an event from an intermediate mass black hole(IMBH) preying on a star.We therefore propose that GRB080503 is also due to a similar event;the mass of the IMBH is estimated to be about 4.6×104 solar masses,and the engulfed star had about the same mass and size as the Sun.We also estimate that the total burst energy is about 7.67× 1050 ergs.
LU Ye & GAO He National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100012,China
