NGC 1275周围纤维状星云的[S II]发射线双线的高光谱分辨率观测
High-spectral-resolution Observations of the [S II] Emission-line Doublet in the Filamentary Nebula Surrounding NGC 1275
AI总结：
本研究通过SITELLE高光谱分辨率观测分析NGC 1275周围纤维状星云的[S II]双线，发现内外纤维密度的二分性，推导了多相环境的温密压关系并探讨相关模型。
AI中文摘要：
我们分析了SITELLE的新的高光谱分辨率观测数据（分辨率R=λ/Δλ=7000），该观测针对英仙座星系团中心星系NGC 1275周围的纤维状星云。我们在此呈现对[S II]λ6716和[S II]λ6731发射线双线的分析，利用其比值确定光学发射纤维的电子密度。我们将这些测量结果与从钱德拉X射线天文台对星系团内介质（ICM）的深度观测中推导的电子密度进行比较，以确定是否存在密度相关性。我们报告了一个清晰的二分性：外部纤维的[S II]发射线比值平均约为1.1，而内部纤维的比值更高，约为1.3。这些结果表明，大多数气体纤维位于密度测量的低密度阈值附近，约为10² cm⁻³。利用径向分布，我们发现内部纤维的密度大致恒定，而ICM密度随半径减小。在外部纤维中，我们观测到ICM与光学纤维密度之间存在局部关联的迹象，但总体上未发现清晰的相关性。我们还将这些密度测量结果与冷分子CO气体观测相结合，推导了NGC 1275周围多相环境的温度、密度和压力之间的关系。最后，我们研究了解释观测密度测量的潜在模型，并探讨了对其他冷核星系团中心星系周围纤维状星云的类似研究。
英文摘要：
We analyze new high-spectral resolution SITELLE observations (R = $λ/Δλ$ = 7000) of the filamentary nebula surrounding NGC 1275, central galaxy of the Perseus cluster. We present here analysis of the \sii$\lambda6716$ and \sii$\lambda6731$ emission line doublet, using its ratio to determine the electron density of the optically emitting filaments. We compare these measurements with electron densities derived from deep Chandra X-ray observations of the intra-cluster medium (ICM) to determine if any correlations in density can be found. We report the detection of a clear dichotomy between the outer filaments, displaying on average lower \sii\text{ }emission line ratio of $\sim 1.1$ and the inner filaments displaying higher ratios of $\sim 1.3$. These results indicate that most of the gaseous filaments lie close to the low-density threshold for the density measurement of $\sim 10^2\text{ cm}^{-3}$. Using radial profiles, we find that the inner filaments have a roughly constant density, whereas the ICM density decreases with radius. In the outer filaments, we observe hints of local connections between the densities of the ICM and optical filaments, but no clear correlation seems to be observed overall. We also combined these density measurements with cold molecular CO gas observations to derive a relationship between temperature, density and pressure for the multiphase environment surrounding NGC 1275. Finally, we investigated potential models to explain the observed density measurements and explored similar studies of filamentary nebula around other central galaxies of cool-core galaxy clusters.
