The stellar population and initial mass function of NGC 1399 with MUSE
The stellar population and initial mass function of NGC 1399 with MUSE
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DOI：
10.1093/mnras/sty1434
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发表时间：
2018-05
影响因子：
4.8
通讯作者：
S. Vaughan;R. Davies;S. Zieleniewski;R. Houghton
中科院分区：
文献类型：
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作者：
S. Vaughan;R. Davies;S. Zieleniewski;R. Houghton
我们给出了星系团中最大的椭圆星系NGC1399的恒星初始质量函数(IMF)的空间分辨测量结果。利用多单元光谱探测器(MUSE)的数据和Conroy等人更新的最先进的恒星群体合成模型，我们使用全光谱拟合来测量作为该天体半径函数的低质量IMF以及一些单独的元素丰度。我们发现NGC1399中的IMF比中心的银河系重，并且在0.7Re的超Salpeter斜率处保持径向不变。在半径大于此的情况下，IMF斜率减小到与MilkyWay IMF在Re之后的边缘一致。推测的中心V带M/L比值与之前报道的动态M/L值符合得很好。测量的M/L比值的径向形式可能是该天体两相形成的证据，中心区域与外围形成不同。我们还测量了一个从NGC1399中心延伸4角秒(404pc，DL=21.1 Mpc)的电离气体空间分辨细丝，其等效宽度很窄，低速色散(65±14公里S-1)。结合发射线比的分析，得出NGC1399‘S活动星系核是电离辐射源的结论。
We present spatially resolved measurements of the stellar initial mass function (IMF) in NGC1399, the largest elliptical galaxy in the Fornax Cluster. Using data from the Multi Unit Spectroscopic Explorer (MUSE) and updated state-of-the-art stellar population synthesis models from Conroy et al., we use full spectral fitting to measure the low-mass IMF, as well as a number of individual elemental abundances, as a function of radius in this object. We find that the IMF in NGC1399 is heavier than the Milky Way in its centre and remains radially constant at a super-Salpeter slope out to 0.7 Re. At radii larger than this, the IMF slope decreases to becomemarginally consistent with aMilkyWay IMF just beyond Re. The inferred central V-band M/L ratio is in excellent agreement with the previously reported dynamical M/L measurement from Houghton et al. The measured radial form of the M/L ratio may be evidence for a two-phase formation in this object, with the central regions forming differently to the outskirts. We also report measurements of a spatially resolved filament of ionized gas extending 4 arcsec (404 pc at DL = 21.1Mpc) from the centre of NGC1399, with very narrow equivalent width and low-velocity dispersion (65 ± 14 km s-1). The location of the emission, combined with an analysis of the emission line ratios, leads us to conclude that NGC1399's AGN is the source of ionizing radiation.