论文标题
折叠中的间歇性流体动力喷射不会产生GRB
Intermittent hydrodynamic jets in collapsars do not produce GRBs
论文作者
论文摘要
强大的变异性是伽马射线爆发（GRB）迅速排放的常见特征。这种观察到的可变性广泛归因于中央发动机的间歇性，这是通过发动机驱除的GRB发射射流中强烈的内部冲击而形成的。在本文中，我们通过数值研究通过倒塌的恒星的包络来定期通过可变发动机注入流体动力喷射的传播。通过后处理3D数值模拟的输出，我们计算流出的净辐射效率。我们发现，所有间歇性喷气式飞机都受到重型重骨污染的约束，该污染物抑制了远低于检测极限的光球及以下的发射。这与连续喷气机相反，如最近所示，由于射流与恒星包络的相互作用，因此产生高度可变的伽马射线光泽发射，并具有很高的效率。我们的结果挑战了流体动力喷气机的可变发动机模型，并可能对GRB发动机的占空比构成限制。如果这种系统在自然界中存在，则不会预期它们会产生明亮的伽马射线发射，而应以X射线，光学和无线电瞬变的形式出现，类似于延迟的GRB余辉信号。
Strong variability is a common characteristic of the prompt emission of gamma-ray bursts (GRB). This observed variability is widely attributed to an intermittency of the central engine, through formation of strong internal shocks in the GRB-emitting jet expelled by the engine. In this paper we study numerically the propagation of hydrodynamic jets, injected periodically by a variable engine, through the envelope of a collapsed star. By post-processing the output of 3D numerical simulations, we compute the net radiative efficiency of the outflow. We find that all intermittent jets are subject to heavy baryon contamination that inhibits the emission at and above the photosphere well below detection limits. This is in contrast to continuous jets that, as shown recently, produce a highly variable gamma-ray photospheric emission with high efficiency, owing to the interaction of the jet with the stellar envelope. Our results challenge the variable engine model for hydrodynamic jets, and may impose constraints on the duty cycle of GRB engines. If such systems exist in nature, they are not expected to produce bright gamma-ray emission, but should appear as X-ray, optical and radio transients that resemble a delayed GRB afterglow signal.
