标题： 使用XRISM/Resolve测量仙后座A的Fe喷发的非对称膨胀 显示英文标题

标题： Measuring the asymmetric expansion of the Fe ejecta of Cassiopeia A with XRISM/Resolve

摘要： 超新星遗迹（SNRs）的膨胀结构对于理解重元素如何分布到空间以及超新星如何爆炸至关重要。 本文研究了年轻的核心坍缩超新星遗迹Cas A的喷出物膨胀结构，并通过XRISM（X射线成像与光谱任务）上的Resolve微型光谱仪对Fe-K复合体进行了多普勒参数映射。 发现铁喷出物在东南方向（SE）呈现蓝移，在西北方向（NW）呈现红移，表明存在不完整的壳状结构，类似于中间质量元素（IMEs），如硅和硫。铁在NW区域的速度偏移为$\sim1400$km~s$^{-1}$，在SE区域的速度偏移为$\sim2160$km~s$^{-1}$，误差范围在几百km~s$^{-1}$左右。 这些值与NW区域的IMEs速度一致，但比SE区域的IMEs速度大，尽管大的误差范围使我们无法得出哪个成分具有显著更高的速度。 IMEs和铁的多普勒偏移和展宽的径向剖面显示中心的线宽更宽，数值为$\sim$2000--3000~km~s$^{-1}$，而在遗迹边缘较小。 这表明铁喷出物可能以不对称的方式扩展，类似于中间质量元素的喷出物，尽管大的误差范围不允许我们下此结论。 此外，我们在东北部喷流区域几乎看不到铁线的总体多普勒展宽，而中间质量元素的线则显示出显著的展宽。 在NW区域没有检测到如此窄的线。这些发现表明喷出物的不对称膨胀可能是由超新星爆炸产生的大规模不对称性驱动的。 这一解释与中微子驱动超新星爆炸模型预测的大规模不对称性一致。 显示英文摘要

摘要： The expansion structure of supernova remnants (SNRs) is important for understanding not only how heavy elements are distributed into space, but also how supernovae explode. The ejecta expansion structure of the young core-collapse SNR Cas A is investigated, with Doppler parameter mapping of the Fe-K complex by the Resolve microcalorimeter onboard the X-ray Imaging and Spectroscopy Mission, XRISM. It is found that the Fe ejecta are blueshifted in the southeast (SE) and redshifted in the northwest (NW), indicating an incomplete shell structure, similar to the intermediate mass elements (IMEs), such as Si and S. The Fe has a velocity shift of $\sim1400$ km~s$^{-1}$ in the NW and $\sim2160$ km~s$^{-1}$ in the SE region, with the error range of a few 100s km~s$^{-1}$. These values are consistent with those for the IMEs in the NW region, whereas larger than those for the IMEs in the SE region, although the large error region prevented us from concluding which component has significantly higher velocity. The line broadening is larger in the center with values of $\sim$2000--3000~km~s$^{-1}$, and smaller near the edges of the remnant. The radial profiles of the Doppler shift and broadening of the IMEs and Fe indicate that the Fe ejecta may expand asymmetrically as IME ejacta, although the large error regions do not allow us to conclude it. Moreover, we see little bulk Doppler broadening of the Fe lines in the northeastern jet region whereas the IME lines exhibit significant broadening. No such narrow lines are detected in the NW region. These findings suggest an asymmetric expansion of the ejecta potentially driven by large-scale asymmetries originating from the supernova explosion. This interpretation aligns with the large-scale asymmetries predicted by models of neutrino-driven supernova explosions.