标题： 用XRISM/Resolve测量仙后座A的铁喷射物的不对称膨胀 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太空中，以及超新星如何爆炸非常重要。 通过搭载在X射线成像和光谱任务（XRISM）上的Resolve微热量计对Fe-K复合体进行多普勒参数映射，研究了年轻的核心坍缩SNR Cas A的喷出物膨胀结构。 发现Fe喷出物在东南（SE）方向呈现蓝移，在西北（NW）方向呈现红移，表明其结构不完整，类似于中等质量元素（IMEs），如Si和S。Fe在NW区域的速度偏移为$\sim1400$km~s$^{-1}$，在SE区域为$\sim2160$km~s$^{-1}$，误差范围为几百km~s$^{-1}$。 这些数值与NW区域的IMEs一致，但比SE区域的IMEs大，尽管较大的误差区域使我们无法确定哪个组分具有显著更高的速度。 中心的线宽更大，值为$\sim$2000--3000~km~s$^{-1}$，而在遗迹边缘附近较小。 IMEs和Fe的多普勒位移和展宽的径向剖面表明，Fe喷出物可能以与IMEs相似的方式不对称膨胀，尽管较大的误差区域不允许我们得出结论。 此外，我们在东北部喷流区域看到Fe线几乎没有整体多普勒展宽，而IMEs线则表现出显著的展宽。 在NW区域没有检测到这样的窄线。 这些发现表明喷出物的不对称膨胀，这可能是由超新星爆炸产生的大尺度不对称性驱动的。 这种解释与中微子驱动的超新星爆炸模型预测的大尺度不对称性一致。 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.