论文标题

模糊暗物质中的动力摩擦:圆形轨道

Dynamical Friction in fuzzy dark matter: circular orbits

论文作者

Buehler, Robin, Desjacques, Vincent

论文摘要

我们研究了作用于模糊暗物质(FDM)背景中圆形移动的Perturber的动力摩擦(DF)。冷凝后,通过满足Schrödinger-Poisson方程的单波函数来描述FDM。可以通过Madelung变换获得等效的流体动力公式。在这里,我们考虑描述并将分析限制为线性响应理论。我们利用流体动力公式来在稳态和有限的时间扰动中为DF提供完全分析的解决方案。我们将我们的预测与波浪方法的数值实现进行了比较,该方法包括非变化的FDM速度分散$σ$。我们的解决方案对于单个和二进制的perturber都有效,只要$σ$显着超过轨道速度$ v_ \ text {circ} $。尽管不再存在(超音速)气态DF的短距离库仑差异,但FDM案例中的DF表现出红外发散,源于Schrödinger方程的(也)扩散性质。我们对有限时间扰动情况的分析表明,密度唤醒通过FDM介质扩散,直到达到其外界。一旦这种瞬态状态结束了,径向和切向DF均以指数衰减的包膜呈稳态溶液振荡。因此,稳态从未实现。我们使用结果来重新访问5个Fornax球形簇的DF衰减时间尺度。我们还指出,紧凑型二进制的灵感可能停滞不前,因为二进制质量中心的DF扭矩有时会翻转迹象,以成为推力而不是阻力(删节)。

We investigate the dynamical friction (DF) acting on circularly-moving perturbers in fuzzy dark matter (FDM) backgrounds. After condensation, FDM is described by a single wave function satisfying a Schrödinger-Poisson equation. An equivalent, hydrodynamic formulation can be obtained through the Madelung transform. Here, we consider both descriptions and restrict our analysis to linear response theory. We take advantage of the hydrodynamic formulation to derive a fully analytic solution to the DF in steady-state and for a finite time perturbation. We compare our prediction to a numerical implementation of the wave approach that includes a non-vanishing FDM velocity dispersion $σ$. Our solution is valid for both a single and a binary perturber in circular motion as long as $σ$ does not significantly exceed the orbital speed $v_\text{circ}$. While the short-distance Coulomb divergence of the (supersonic) gaseous DF is no longer present, DF in the FDM case exhibits an infrared divergence which stems from the (also) diffusive nature of the Schrödinger equation. Our analysis of the finite time perturbation case reveals that the density wake diffuses through the FDM medium until it reaches its outer boundary. Once this transient regime is over, both the radial and tangential DF oscillate about the steady-state solution with an exponentially decaying envelope. Steady-state is thus never achieved. We use our results to revisit the DF decay timescales of the 5 Fornax globular clusters. We also point out that the inspiral of compact binary may stall because the DF torque about the binary center-of-mass sometimes flips sign to become a thrust rather than a drag (abridged).

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源