利用加拿大-法国-夏威夷望远镜（CFHT）的SITELLE探测蟹状星云（Crab Nebula）中长期寻找的超新星遗迹（supernova remnant）壳层

本文利用加拿大-法国-夏威夷望远镜（CFHT）上的SITELLE成像傅里叶变换分光仪（FTS），对蟹状星云进行了深度的宽视场积分场光谱学观测。研究旨在寻找预期的超新星壳层，但未在观测区域内发现具有统计学意义的日冕谱线发射。研究结果为蟹状星云超新星遗迹壳层的存在提供了目前最深的光学观测限制。

arXiv:2608.26280v1 Announce Type: new Abstract: We present deep, wide-field integral field spectroscopy of the Crab nebula obtained with the imaging Fourier transform spectrometer SITELLE at the Canada--France--Hawaii Telescope (CFHT), to search for the long-sought forward shock. Our observations target the coronal line [Fe XIV]$\lambda$5303, a tracer of shock-heated gas, over two $11^{\prime} \times 11^{\prime}$ fields that probe projected radii of $\sim$2.4--10~pc west of the pulsar, encompassing the range in which a supernova shell is expected. After data processing and a search over the full field of view, we found no statistically significant [Fe XIV] emission in the surveyed regions. We derive a conservative average surface-brightness upper limit of $\lesssim 3.79 \times 10^{-17}~\mathrm{erg}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}~\mathrm{arcsec}^{-2}$ over three representative annuli. This represents the deepest large-area optical constraint on coronal iron emission beyond the visible nebula from the Crab's putative supernova remnant (SNR) shell. Our results are consistent with scenarios in which the forward shock is expanding into a very low-density medium, the shocked gas is weak or underionized, or the shell lies outside the observed region. This work demonstrates the power of wide-field optical integral field spectroscopy for constraining faint, large-scale structures in SNRs.