发表机构
Korea Astronomy and Space Science Institute; University of Science and Technology（韩国天文与空间科学研究所; 科学技术大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出时域框架TransRAT，模拟尘埃对暂现辐照的响应，预测排列与破碎的观测特征，揭示暂现源的化石印记。
AI 中文摘要
我们提出了TransRAT，一个自洽的时域框架，用于追踪尘埃对暂现辐照的耦合动力学响应，并预测其可观测特征。我们将TransRAT应用于一个由IIP型超新星照亮的单区分子云。辐射加热提高尘埃温度，改变磁化率和拉莫尔进动，而增强的辐射场加速辐射进动，并可将排列轴从磁场方向（B-RAT）切换到辐射方向（k-RAT）。同时，强辐射力矩（RATs）使尘埃排列速度快于气体随机化，将快速排列扩展到更小的颗粒尺寸，并通过RAT破碎（RAT-D）破碎大颗粒，不可逆地改变颗粒尺寸分布。随着暂现源消退，排列轴以受磁化率控制的速度返回到磁场方向，而增强的排列颗粒群和经RAT-D修改的颗粒尺寸分布可能在辐射消退后持续存在——这被称为物理记忆效应。尘埃排列和破碎的时间依赖演化产生独特的观测特征：消光和热尘埃偏振的耀发，随后是RAT-D引起的下降；偏振峰值波长λ_max的蓝移；当RAT-D移除大尺寸高角动量（高J）排列颗粒并留下低J颗粒与kRAT对齐时，偏振角旋转等于投影的磁场-辐射方向分离角（在我们采用的几何中为45°），随后随着排列返回到磁场方向而出现角度回响；以及R_V的非单调演化。暂现辐照的持久观测表现，包括增强的偏振、蓝移的λ_max、修改的R_V和偏振角演化，构成了过去宇宙暂现源的化石印记。
英文摘要
We introduce {\it TransRAT}, a self-consistent time-domain framework that follows the coupled dynamical response of dust to transient irradiation and predicts its observable signatures. We apply {\it TransRAT} to a Type~IIP supernova illuminating a one-zone molecular cloud. Radiative heating raises the grain temperature, modifying the magnetic susceptibility and Larmor precession, while the enhanced radiation field accelerates radiative precession and can switch the alignment axis from the magnetic field (B-RAT) to the radiation direction (k-RAT). Simultaneously, strong RATs align grains faster than gas randomization, extending {\it fast alignment} to smaller grain sizes, and disrupt large grains through RAT disruption (RAT-D), irreversibly modifying the grain size distribution. As the transient fades, the alignment axis returns to ${\bf B}$ at a rate controlled by the magnetic susceptibility, whereas the enhanced aligned-grain population and RAT-D-modified grain size distribution can persist long after the radiation has faded- referred to as \emph{physical memory effects}. The time-dependent evolution of grain alignment and disruption produces distinctive observational signatures: a flare in extinction and thermal dust polarization followed by a RAT-D-induced dip; a blueward shift of the polarization peak $λ_{\max}$; a polarization-angle rotation equal to the projected ${\bf B}$--${\bf k}$ separation ($45^{\circ}$ for our adopted geometry) when RAT-D removes large high-$J$ aligned grains and leaves low-$J$ grains aligned with kRAT followed by angle reverberation as alignment returns to ${\bf B}$; and a non-monotonic evolution of $R_V$. The persistent observational manifestations of the transient irradiation, including enhanced polarization, blueshifted $λ_{\max}$, modified $R_V$, and polarization-angle evolution, constitute \emph{fossil imprints} of past cosmic transients.
Comments38 pages, 17 figures; comments welcome
