逆康普顿阻力作用下流体声色散关系的线性不稳定性与阻尼

中文摘要 AI 辅助

外部辐射场的逆康普顿散射产生的辐射阻力会改变相对论流体的声色散关系。我们推导了线性色散关系，并表明，根据电子分布和流体声速的不同，辐射阻力要么对两种模式都产生阻尼，要么对一种模式产生阻尼的同时驱动另一种模式失稳。这种不稳定增长在短波长下是稳健的，但在长波长下则缓慢且过阻尼，此时线性分析受到背景加速度的限制。由此产生的增长率和阻尼率量级与体辐射加速度率相当，因此每当辐射阻力对背景流重要时，其对流体扰动的影响也同样重要。在广泛的参数范围内存在一个纯阻尼区域。辐射阻力还使声波具有色散性：相速度在较长波长处偏离普通声速，并在短波长处趋近于声速。我们使用狭义相对论流体动力学模拟验证了所推导的速率。我们将所推导的关系应用于天体物理喷流，如伽马射线暴、主活动星系核宽线区中的耀变体，以及穿过宇宙微波背景和星系辐射场的类星体喷流。我们发现，所推导的不稳定性、阻尼和色散可能在多种相对论性外流条件下具有相关性。

英文摘要

Radiation drag from inverse-Compton scattering of an external radiation field changes the acoustic dispersion relation of a relativistic fluid. We derive the linear dispersion relation and show that, depending on the electron distribution and fluid sound speed, radiation drag either damps both modes or damps one while driving the other unstable. The unstable growth is robust at short wavelengths but slow and overdamped at long wavelengths, where the linear analysis is limited by the background acceleration. The resulting growth and damping rates are of order the bulk radiative acceleration rate, so whenever radiation drag is important for the background flow, its effects on fluid perturbations are also important. A purely damped region exists for a wide range of parameters. Radiation drag also makes acoustic waves dispersive: The phase speed deviates from the ordinary sound speed at longer wavelengths, and approaches the sound speed at short wavelengths. We validate the derived rates using special-relativistic hydrodynamic simulations. We apply the derived relation to astrophysical jets such as gamma-ray bursts, blazars in the broad-line region of the host active galactic nucleus, and quasar jets traveling through the CMB and galactic radiation field. We find that the derived instability, damping and dispersion may be relevant across a range of relativistic outflow conditions.

发表机构

• University of Wisconsin-Madison（威斯康星大学麦迪逊分校）

机构由 AI 辅助整理，请以论文原文为准。

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6 figures