Gamma-ray bursts (GRBs) are the most powerful explosions in the universe. Over the past two decades, several GRB energy and luminosity correlations were discovered. These correlations typically involve an observable p...Gamma-ray bursts (GRBs) are the most powerful explosions in the universe. Over the past two decades, several GRB energy and luminosity correlations were discovered. These correlations typically involve an observable parameter, like the observed peak energy, Ep,obs, and a non-observable quantity, like the equivalent isotropic energy, Eiso. This paper provides a brief review of GRB peak energy correlations. Specifically, it focuses on the Amati relation, which correlates Ep,obs and Eiso, and the Ghirlanda relation, which correlates Ep,obs and Ey, the total energy corrected for beaming. The paper also discusses the physical interpretation of these relations in the context of the internal shock model.展开更多
伽马射线暴(Gamma Ray Burst,GRB)的分类问题是天文学领域中未解决的热点问题。根据不同方法采用不同指标进行分类,导致的分类结果也不同。为了建立更合理的分类指标,本文以静止系峰值能量E_(p,i) E、各向同性瞬时等值能量E_(iso) 、瞬...伽马射线暴(Gamma Ray Burst,GRB)的分类问题是天文学领域中未解决的热点问题。根据不同方法采用不同指标进行分类,导致的分类结果也不同。为了建立更合理的分类指标,本文以静止系峰值能量E_(p,i) E、各向同性瞬时等值能量E_(iso) 、瞬时辐射持续时间T_(90,i) 作为解释变量,建立了广义线性分类模型,得到了一个新的分类响应指标gEHD。通过在benchmark数据集上的实验表明,gEHD指标和EHD指标具有等效的分类结果,可作为伽马射线暴Ⅰ型/Ⅱ型的一种新的分类依据。展开更多
Gamma-ray bursts (GRBs) are by far the most powerful explosions in the universe. Over the past two decades, several GRB energy and luminosity correlations were discovered for long gamma-ray bursts, which are bursts wh...Gamma-ray bursts (GRBs) are by far the most powerful explosions in the universe. Over the past two decades, several GRB energy and luminosity correlations were discovered for long gamma-ray bursts, which are bursts whose observed duration exceeds 2 seconds. One important correlation, the Amati relation, involves the observed peak energy, <em>E</em><sub><em>p,obs</em></sub>, in the <em>v</em>F<em><sub>v</sub></em> spectrum and the equivalent isotropic energy, <em>E</em><sub><em>iso</em></sub>. For many years, it was believed that the Amati correlation applied only to long GRBs. In this paper, we use a recent data sample that includes both long and short GRBs to re-examine the issue of whether the Amati correlation applies to long GRBs only. Our results indicate that although short bursts do not follow the Amati relation in the strict sense, they do exhibit a correlation between the intrinsic peak energy, <em>E</em><em><sub>p,i</sub></em>, and <em>E<sub>iso</sub></em> that is very similar to the Amati relation but with a different normalization and slope. The paper also discusses the physical interpretation of this correlation in the context of the internal shock model.展开更多
Gamma-ray bursts (GRBs) are the most intense and powerful explosions in the universe. Based on their observed duration, they are traditionally divided into long bursts whose observed duration equals or exceeds 2 s, an...Gamma-ray bursts (GRBs) are the most intense and powerful explosions in the universe. Based on their observed duration, they are traditionally divided into long bursts whose observed duration equals or exceeds 2 s, and short bursts whose observed duration is less than 2 s. Several GRB energy and luminosity correlations have been discovered for long gamma-ray bursts. Two important correlations are the Amati relation and the Yonetoku relation. The Amati relation is a correlation between the intrinsic peak energy, E<sub>p</sub><sub>,i</sub>, obtained from the νF<sub>ν</sub> spectrum and the equivalent isotropic energy, E<sub>iso</sub>, while the Yonetoku relation is a correlation between E<sub>p,i</sub> and the peak isotropic luminosity, L<sub>iso</sub>. In this paper, we use a recent data sample that includes both long and short GRBs to compare these two correlations for the two groups of bursts. We also compare the E<sub>iso</sub>-L<sub>iso</sub> plane for these two types of bursts. Our results indicate that both long and short bursts adhere to these two correlations but with different normalizations. We also find that the E<sub>iso</sub>-L<sub>iso</sub> plane is similar for both types of GRBs but is shifted to lower values of E<sub>iso</sub> for short GRBs.展开更多
The capacity of energy absorption by fault bands after rock burst wascalculated quantitatively according to shear stress-shear deformation curves considering theinteractions and interplaying among microstructures due ...The capacity of energy absorption by fault bands after rock burst wascalculated quantitatively according to shear stress-shear deformation curves considering theinteractions and interplaying among microstructures due to the heterogeneity of strain softeningrock materials. The post-peak stiffness of rock specimens subjected to direct shear was derivedstrictly based on gradient-dependent plasticity, which can not be obtained from the classicalelastoplastic theory. Analytical solutions for the dissipated energy of rock burst were proposedwhether the slope of the post-peak shear stress-shear deformation curve is positive or not. Theanalytical solutions show that shear stress level, confining pressure, shear strength, brittleness,strain rate and heterogeneity of rock materials have important influence on the dissipated energy.The larger value of the dissipated energy means that the capacity of energy dissipation in the formof shear bands is superior and a lower magnitude of rock burst is expected under the condition ofthe same work done by external shear force. The possibility of rock burst is reduced for a lowersoftening modulus or a larger thickness of shear bands.展开更多
文摘Gamma-ray bursts (GRBs) are the most powerful explosions in the universe. Over the past two decades, several GRB energy and luminosity correlations were discovered. These correlations typically involve an observable parameter, like the observed peak energy, Ep,obs, and a non-observable quantity, like the equivalent isotropic energy, Eiso. This paper provides a brief review of GRB peak energy correlations. Specifically, it focuses on the Amati relation, which correlates Ep,obs and Eiso, and the Ghirlanda relation, which correlates Ep,obs and Ey, the total energy corrected for beaming. The paper also discusses the physical interpretation of these relations in the context of the internal shock model.
文摘Gamma-ray bursts (GRBs) are by far the most powerful explosions in the universe. Over the past two decades, several GRB energy and luminosity correlations were discovered for long gamma-ray bursts, which are bursts whose observed duration exceeds 2 seconds. One important correlation, the Amati relation, involves the observed peak energy, <em>E</em><sub><em>p,obs</em></sub>, in the <em>v</em>F<em><sub>v</sub></em> spectrum and the equivalent isotropic energy, <em>E</em><sub><em>iso</em></sub>. For many years, it was believed that the Amati correlation applied only to long GRBs. In this paper, we use a recent data sample that includes both long and short GRBs to re-examine the issue of whether the Amati correlation applies to long GRBs only. Our results indicate that although short bursts do not follow the Amati relation in the strict sense, they do exhibit a correlation between the intrinsic peak energy, <em>E</em><em><sub>p,i</sub></em>, and <em>E<sub>iso</sub></em> that is very similar to the Amati relation but with a different normalization and slope. The paper also discusses the physical interpretation of this correlation in the context of the internal shock model.
文摘Gamma-ray bursts (GRBs) are the most intense and powerful explosions in the universe. Based on their observed duration, they are traditionally divided into long bursts whose observed duration equals or exceeds 2 s, and short bursts whose observed duration is less than 2 s. Several GRB energy and luminosity correlations have been discovered for long gamma-ray bursts. Two important correlations are the Amati relation and the Yonetoku relation. The Amati relation is a correlation between the intrinsic peak energy, E<sub>p</sub><sub>,i</sub>, obtained from the νF<sub>ν</sub> spectrum and the equivalent isotropic energy, E<sub>iso</sub>, while the Yonetoku relation is a correlation between E<sub>p,i</sub> and the peak isotropic luminosity, L<sub>iso</sub>. In this paper, we use a recent data sample that includes both long and short GRBs to compare these two correlations for the two groups of bursts. We also compare the E<sub>iso</sub>-L<sub>iso</sub> plane for these two types of bursts. Our results indicate that both long and short bursts adhere to these two correlations but with different normalizations. We also find that the E<sub>iso</sub>-L<sub>iso</sub> plane is similar for both types of GRBs but is shifted to lower values of E<sub>iso</sub> for short GRBs.
基金This work was financially supported by the National Natural Science Foundation of China (No.50309004).
文摘The capacity of energy absorption by fault bands after rock burst wascalculated quantitatively according to shear stress-shear deformation curves considering theinteractions and interplaying among microstructures due to the heterogeneity of strain softeningrock materials. The post-peak stiffness of rock specimens subjected to direct shear was derivedstrictly based on gradient-dependent plasticity, which can not be obtained from the classicalelastoplastic theory. Analytical solutions for the dissipated energy of rock burst were proposedwhether the slope of the post-peak shear stress-shear deformation curve is positive or not. Theanalytical solutions show that shear stress level, confining pressure, shear strength, brittleness,strain rate and heterogeneity of rock materials have important influence on the dissipated energy.The larger value of the dissipated energy means that the capacity of energy dissipation in the formof shear bands is superior and a lower magnitude of rock burst is expected under the condition ofthe same work done by external shear force. The possibility of rock burst is reduced for a lowersoftening modulus or a larger thickness of shear bands.
