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arXiv · 1109.3757

Lorentz Factor-Isotropic Luminosity/Energy Correlations of GRBS and Their Interpretation

Jing Lv·Yuan-Chuan Zou·Wei-Hua Lei·Bing Zhang·Qing-Wen Wu·Ding-Xiong Wang·En-Wei Liang·Hou-Jun Lv
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Abstract

The bulk Lorentz factor of the gamma-ray burst (GRB) ejecta (Gamma_0) is a key parameter to understand the GRB physics. Liang et al. have discovered a correlation between Gamma_0 and isotropic gamma-ray energy: Gamma_0\proptoE_{gamma,iso,52}^{0.25}. By including more GRBs with updated data and more methods to derive Gamma_0, we confirm this correlation and obtain Gamma_0~91E_{gamma,iso,52}^{0.29}. Evaluating the mean isotropic gamma-ray luminosities L_{gamma,iso} of the GRBs in the same sample, we discover an even tighter correlation Gamma_0~249 L_{gamma,iso,52}^{0.30}. We propose an interpretation to this later correlation. Invoking a neutrino-cooled hyperaccretion disk around a stellar mass black hole as the central engine of GRBs, we derive jet luminosity powered by neutrino annihilation and baryon loading from a neutrino-driven wind. Applying beaming correction, we finally derive Gamma_0\proptoL_{gamma,iso}^{0.22}, which is well consistent with the data. This suggests that the central engine of long GRBs is likely a stellar mass black hole surrounded by a hyper-accreting disk.

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Jing Lv, Yuan-Chuan Zou, Wei-Hua Lei, Bing Zhang, Qing-Wen Wu, Ding-Xiong Wang, En-Wei Liang, Hou-Jun Lv. 2011-09-17. Lorentz Factor-Isotropic Luminosity/Energy Correlations of GRBS and Their Interpretation. https://doi.org/10.1088/0004-637x/751/1/49

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