A VLT VIMOS integral-field spectroscopic study of perturbed blue compact galaxies: UM 420 and UM 462
A VLT VIMOS integral-field spectroscopic study of perturbed blue compact galaxies: UM 420 and UM 462
复制标题
对扰动蓝色致密星系的 VLT VIMOS 积分场光谱研究：UM 420 和 UM 462
DOI：
10.1111/j.1365-2966.2009.15706.x
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发表时间：
2010
影响因子：
4.8
通讯作者：
James B
中科院分区：
文献类型：
--
作者：
James B
利用13 × 13 arcsec ~ 2可见光多目标摄谱仪积分场单元，以0.33 × 0.33 arcsec ~ 2的分辨率，对两个不相关的蓝色致密星系进行了光学积分场谱学研究。 给出了[Oiii]λ5007、Hα和[Nii]λ6584的连续谱和扣除背景的谱线图。这两个星系都显示出正在进行的扰动和/或相互作用的迹象。UM 420首次被解析为由两个星爆式分量组成的合并系统，其中最大的分量具有“臂状”结构。UM 462是一个不规则形态的破裂系统，被分解成至少四个星爆区。讨论了Hα径向速度图和半峰全宽图。由于两个星系的发射线都只与单一的高斯分布很好地拟合，因此没有从两个星系中检测到潜在的宽线区域。电子温度和密度以及氦、氧、氮和硫的丰度是根据整个星系和每个最近星星形成区域的光谱计算出来的。地图的O/H比：这些星系显示的氧丰度是太阳的20%。没有证据表明星系之间的大量丰度变化会指向显着的氮或氧自我富集被发现（10.2 dex极限）。与以前的观测结果相反，这种分析不支持这些蓝色致密矮星系作为沃尔夫-拉叶星系的分类，因为在我们的光谱中没有检测到宽发射线特征。由逐像素的Baldwin-Phillips-Terlevich发射线比图可知，这些系统的光谱主要由恒星光电离激发。
We report on optical integral-field spectroscopy of two unrelated blue compact galaxies mapped with the 13 × 13 arcsec2Visible Multi-Object Spectrograph integral field unit at a resolution of 0.33 × 0.33 arcsec2. Continuum and background subtracted emission line maps in the light of [Oiii]λ5007, Hα and [Nii]λ6584 are presented. Both galaxies display signs of ongoing perturbation and/or interaction. UM 420 is resolved for the first time to be a merging system composed of two starbursting components with an ‘arm-like’ structure associated with the largest component. UM 462 which is a disrupted system of irregular morphology is resolved into at least four starbursting regions. Maps of the Hα radial velocity and full width at half-maximum are discussed. No underlying broad-line region was detected from either galaxy as the emission lines are well fitted with single Gaussian profiles only. Electron temperatures and densities as well as the abundances of helium, oxygen, nitrogen and sulphur were computed from spectra integrated over the whole galaxies and for each area of recent star formation. Maps of the O/H ratio are presented: these galaxies show oxygen abundances that are ∼20 per cent solar. No evidence of substantial abundance variations across the galaxies that would point to significant nitrogen or oxygen self-enrichment is found (≲0.2 dex limit). Contrary to previous observations, this analysis does not support the classification of these blue compact dwarf galaxies as Wolf–Rayet galaxies as the characteristic broad-emission-line features have not been detected in our spectra. Baldwin–Phillips–Terlevich emission-line-ratio diagrams which were constructed on a pixel-by-pixel basis indicate that the optical spectra of these systems are predominantly excited by stellar photoionization.