Deciphering the Origin of Ionized Gas in IC 1459 with VLT/MUSE
Deciphering the Origin of Ionized Gas in IC 1459 with VLT/MUSE
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使用 VLT/MUSE 破译 IC 1459 中电离气体的来源
DOI：
10.1093/mnras/stab1137
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发表时间：
2021
影响因子：
4.8
通讯作者：
Jorgenson, R A
中科院分区：
文献类型：
--
作者：
Mulcahey, C R;Prichard, L J;Krajnović, D;Jorgenson, R A
IC1459是一个具有快速逆旋转恒星核的早期类型星系(ETG)，是富含气体的螺旋星系群中的中心星系。在这项工作中，我们研究了IC1459中丰富的电离气体，并提出了新的恒星轨道模型，以连接其复杂的观测性质阵列，并建立了更完整的演化图景。利用甚大望远镜(VLT)上的光学积分场单元(IFU)多单元光谱探测器(MUSE)，我们研究了IC1459的气体和恒星性质，以破译该星系电离气体的来源和提供能量的机制。我们探测到非圆盘状结构中的电离气体，该结构与中心恒星的旋转方向相反。利用全光谱拟合的发射线通量比和速度弥散，我们在IC1459中发现了两个运动学上截然不同的激波发射线气体区域，这两个区域是用窄(σ≤)(155万公里S−1)和宽(σ>；155百万公里S−1)剖面区分的。我们的结果表明，IC1459中的发射线气体与其反旋转恒星成分的来源不同。我们认为，电离气体来自于群环境气体的晚期吸积，这种吸积发生在中心恒星组分形成很久之后。我们发现激波加热和活动星系核活动都是IC1459的电离机制，但主要的激发机制是来自其旧恒星群的后渐近巨星分支恒星。
IC 1459 is an early-type galaxy (ETG) with a rapidly counter-rotating stellar core, and is the central galaxy in a gas-rich group of spirals. In this work, we investigate the abundant ionized gas in IC 1459 and present new stellar orbital models to connect its complex array of observed properties and build a more complete picture of its evolution. Using the Multi-Unit Spectroscopic Explorer (MUSE), the optical integral field unit (IFU) on the Very Large Telescope (VLT), we examine the gas and stellar properties of IC 1459 to decipher the origin and powering mechanism of the galaxy’s ionized gas. We detect ionized gas in a non-disc-like structure rotating in the opposite sense to the central stars. Using emission-line flux ratios and velocity dispersion from full-spectral fitting, we find two kinematically distinct regions of shocked emission-line gas in IC 1459, which we distinguished using narrow (σ ≤ 155 km s−1) and broad (σ > 155 km s−1) profiles. Our results imply that the emission-line gas in IC 1459 has a different origin than that of its counter-rotating stellar component. We propose that the ionized gas is from late-stage accretion of gas from the group environment, which occurred long after the formation of the central stellar component. We find that shock heating and AGN activity are both ionizing mechanisms in IC 1459 but that the dominant excitation mechanism is by post-asymptotic giant branch stars from its old stellar population.