论文标题
太阳系周围的捕获星际物质的光环
A halo of trapped interstellar matter surrounding the solar system
论文作者
论文摘要
本文表明，穿越星系的引诱体可以将带有小相对速度的附近的较轻的星际颗粒捕获到暂时结合的轨道上。捕获机制是由银河潮汐场驱动的，后者可以将其结合能变为负面的程度。随着时间的流逝，被困的颗粒会产生局部密度或“光晕”，该密度达到稳定状态，因为被捕获的颗粒数量等于潮湿。本文使用经典的随机技术来计算被点质量捕获的颗粒的捕获率和相位分布。在稳态状态下，结合粒子会产生密度增强，该密度增强为$δ（r）\ sim r^{ - 3/2} $（a.k.a“密度尖峰”），然后遵循速度分散型$σ_H（r）\ sim r^{ - 1/2} $。无碰撞的$ n $ - 体实验与距离范围内的这些理论预测$ r \ gtrsimr_ε$，其中$r_ε\ simeq 0.8 \，\ exp [-v_ v _ \ star^2/（2σ^2）通过具有速度分散$σ$的颗粒海洋。初步估计忽略了与行星和银河系的碰撞的初步估计，表明太阳系可能被halo包围，其中包含$ n^{\ rm iso}的顺序（<0.1 \，{\ rm pc}） dm}（<0.1 \，{\ rm pc}）\ sim 10^{ - 13} m_ \ odot $。太阳系中捕获的星际物质的存在可能会影响Oort云的大小的电流估计，并在直接暗物质检测实验中留下明显的信号。
This paper shows that gravitating bodies travelling through the Galaxy can trap lighter interstellar particles that pass nearby with small relative velocities onto temporarily-bound orbits. The capture mechanism is driven by the Galactic tidal field, which can decelerate infalling objects to a degree where their binding energy becomes negative. Over time, trapped particles build a local overdensity -- or `halo'-- that reaches a steady state as the number of particles being captured equals that being tidally stripped. This paper uses classical stochastic techniques to calculate the capture rate and the phase-space distribution of particles trapped by a point-mass. In a steady state, bound particles generate a density enhancement that scales as $δ(r)\sim r^{-3/2}$ (a.k.a `density spike') and follow a velocity dispersion profile $σ_h(r)\sim r^{-1/2}$. Collisionless $N$-body experiments show excellent agreement with these theoretical predictions within a distance range $r\gtrsim r_ε$, where $r_ε\simeq 0.8\,\exp[-V_\star^2/(2σ^2)]\,Gm_\star/σ^2$ is the thermal critical radius of a point-mass $m_\star$ moving with a speed $V_\star$ through a sea of particles with a velocity dispersion $σ$. Preliminary estimates that ignore collisions with planets and Galactic substructures suggest that the solar system may be surrounded by a halo that contains the order of $N^{\rm ISO}(<0.1\,{\rm pc})\sim 10^7$ energetically-bound 'Oumuamua-like objects, and a dark matter mass of $M^{\rm DM}(<0.1\,{\rm pc})\sim 10^{-13}M_\odot$. The presence of trapped interstellar matter in the solar system can affect current estimates on the size of the Oort Cloud, and leave a distinct signal in direct dark matter detection experiments.
