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arXiv 1102.4571astro-ph.HE
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低能伽马射线暴的合成离轴光变曲线

Synthetic off-axis light curves for low energy gamma-ray bursts

H. J. van Eerten, A. I. MacFadyen

摘要:

我们提出了大量的伽马射线暴(GRB)余辉光变曲线计算的结果,通过结合高分辨率的二维相对论流体力学模拟使用RAM与同步辐射代码。结果得到射流能量,环爆介质密度和射流角度典型的短和underluminous GRB,不同的观察者角度和观察者频率从低无线电(75 MHz)的X射线(1.5千电子伏)。我们总结了光变曲线,通过光滑的幂律拟合与多达三个休息,涵盖小的观察者角度的射流休息,大的观察者角度的上升阶段和反喷的上升和衰减。所有光变曲线数据均可通过http://cosmo.nyu.edu/afterglowlibrary公开获取。这些数据可以用于模型拟合观测数据,并作为预测未来望远镜(如LOFAR或SKA)观测结果的辅助工具,并将有利于使用不同通道(如LIGO或Virgo的引力波观测)研究中子星合并。对于小的观察者角度,我们发现喷流中断时间在频率之间变化很大,无线电中的中断时间大大推迟。增加观察者角度也推迟了测量的射流中断时间。对于大的观察者角度,光变曲线的上升阶段具有复杂的形状,不能总是由简单的幂律来概括。除了非常大的观测角度外,反喷流是光变曲线中的一个明显特征,尽管在实践中,到那时信号将非常难以观察。

英文摘要:

We present results for a large number of gamma-ray burst (GRB) afterglow light curve calculations, done by combining high resolution two-dimensional relativistic hydrodynamics simulations using RAM with a synchrotron radiation code. Results were obtained for jet energies, circumburst medium densities and jet angles typical for short and underluminous GRBs, different observer angles and observer frequencies from low radio (75 MHz) to X-ray (1.5 keV). We summarize the light curves through smooth power law fits with up to three breaks, covering jet breaks for small observer angles, the rising phase for large observer angles and the rise and decay of the counterjet. All light curve data are publicly available via http://cosmo.nyu.edu/afterglowlibrary . The data can be used for model fits to observational data and as an aid for predicting observations by future telescopes such as LOFAR or SKA and will benefit the study of neutron star mergers using different channels, such as gravitational wave observations with LIGO or Virgo. For small observer angles, we find jet break times that vary significantly between frequencies, with the break time in the radio substantially postponed. Increasing the observer angle also postpones the measured jet break time. The rising phase of the light curve for large observer angle has a complex shape that can not always be summarized by a simple power law. Except for very large observer angles, the counter jet is a distinct feature in the light curve, although in practice the signal will be exceedingly difficult to observe by then.

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