早型星系NGC 4697球盘的VIMOS镶嵌积分场谱学
VIMOS mosaic integral-field spectroscopy of the bulge and disk of the early-type galaxy NGC 4697
摘要：
我们提出了一个积分场研究的内部结构，运动学和恒星人口的几乎边缘上，中等光度（$L_ {*}$）椭圆星系NGC 4697。我们建立了扩展的2维（2D）地图的恒星运动学和线强度的星系$\sim 0.7 $有效半径（R $_{eff}$）使用8个VIMOS（VLT上的可见多对象摄谱仪）积分场单位点的马赛克。我们找到了明确的证据旋转支持的结构沿主轴从二维运动学地图，确认了以前的分类，这个系统作为一个“快速通道”。我们研究了视线速度分布（LOSVD）的第三和第四高斯-厄米特矩$h_3$和$h_4$与旋转参数（$V/σ$）之间的相关性，并将我们的研究结果与流体动力学模拟进行了比较。我们发现显着的相似之处，从丰富的气体合并的预测。基于光度学，我们进行了球/盘分解，并研究了这两个组成部分的恒星布居特性。隆起和盘状星云显示出不同的恒星族群，隆起中的恒星年龄较大（年龄为$_{\rm bulge}=13.5^{+1.4}_{-1.4}$ Gyr，年龄为$_{\rm disk}=10.5^{+1.6}_{-2.0}$ Gyr），金属含量较低（$\mathrm{[M/H]_{bulge}} = -0.17^{+0.12}_{-0.1}$，$\mathrm{[M/H]_{disk}}=-0.03^{+0.02}_{-0.1}$）。后来形成的证据，更多的金属丰富的磁盘嵌入在一个较老的，更贫金属的隆起，连同LOSVD结构，支持的质量组装方案占主导地位的气体丰富的小合并，并可能与后期气体丰富的主要合并，留下了以前快速旋转的系统不变。凸起和盘没有显示出不同的恒星初始质量函数斜率的迹象，两者都与银河系一样的IMF匹配良好。
英文摘要：
We present an integral field study of the internal structure, kinematics and stellar population of the almost edge-on, intermediate luminosity ($L_ {*}$) elliptical galaxy NGC 4697. We build extended 2-dimensional (2D) maps of the stellar kinematics and line-strengths of the galaxy up to $\sim 0.7 $ effective radii (R$_{eff}$) using a mosaic of 8 VIMOS (VIsible Multi-Objects Spectrograph on the VLT) integral-field unit pointings. We find clear evidence for a rotation-supported structure along the major axis from the 2D kinematical maps, confirming the previous classification of this system as a `fast-rotator'. We study the correlations between the third and fourth Gauss-Hermite moments of the line-of-sight velocity distribution (LOSVD) $h_3$ and $h_4$ with the rotation parameter ($V/σ$), and compare our findings to hydrodynamical simulations. We find remarkable similarities to predictions from gas-rich mergers. Based on photometry, we perform a bulge/disk decomposition and study the stellar population properties of the two components. The bulge and the disk show different stellar populations, with the stars in the bulge being older (age$_{\rm bulge}=13.5^{+1.4}_{-1.4}$ Gyr, age$_{\rm disk}=10.5^{+1.6}_{-2.0}$Gyr) and more metal-poor ($\mathrm{[M/H]_{bulge}} = -0.17^{+0.12}_{-0.1}$, $\mathrm{[M/H]_{disk}}=-0.03^{+0.02}_{-0.1}$). The evidence of a later-formed, more metal-rich disk embedded in an older, more metal-poor bulge, together with the LOSVD structure, supports a mass assembly scenario dominated by gas-rich minor mergers and possibly with a late gas-rich major merger that left a previously rapidly rotating system unchanged. The bulge and the disk do not show signs of different stellar Initial Mass Function slopes, and both match well with a Milky Way-like IMF.
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