The SAURON project - XVIII. The integrated UV-line-strength relations of early-type galaxies The SAURON project - XVIII
The SAURON project - XVIII. The integrated UV-line-strength relations of early-type galaxies The SAURON project - XVIII
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索伦计划 - XVIII。
DOI：
10.1111/j.1365-2966.2011.18489.x
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发表时间：
2011
影响因子：
4.8
通讯作者：
Bureau M
中科院分区：
文献类型：
--
作者：
Bureau M
利用星系演化探索者（GALEX）卫星的远紫外（FUV）和近紫外（NUV）光度法、MDM天文台的光学光度法和SAURON的光学积分场光谱法，我们探索了SAURON样本中48个附近早型星系的紫外线强度关系。所有数量使用相同的光圈，避免光圈不匹配。我们发现，具有纯古老恒星群的星系显示出明确的综合FUV - Vand FUV - NUV颜色与综合Mgband Hβ吸收线强度指数的相关性，其中FUV - NUV最强。与NUV−vcolor、Fe5015指数和恒星速度色散σ的相关性要弱得多。这些相关性对早期型星系中紫外线上升现象的起源提出了严格的限制，并强调了它对年龄和金属丰度的依赖。特别是，尽管最近有争论，我们恢复了FUV - v颜色和Mg线强度之间的负相关关系，我们称之为“Burstein关系”，表明UV上升与金属丰度有正相关关系。我们认为，相关性中的散射是真实的，并且提供了轻微的证据，表明强烈的紫外线过剩优先出现在慢旋转星系中。我们还证明了相关性中的大多数异常值是当前或最近形成恒星的星系，其中一些水平非常低。我们相信，这种对弱恒星形成的敏感性，由索伦样本提供的深度和多样化的数据所提供，解释了为什么我们的结果偶尔与最近其他较浅的调查结果不一致。斯隆数字巡天（SDSS）对更遥远的早期星系进行了大量精心制作的样本分析，更容易与当前和未来的大型巡天进行比较。
Using far-ultraviolet (FUV) and near-ultraviolet (NUV) photometry from guest investigator programmes on theGalaxy Evolution Explorer(GALEX) satellite, optical photometry from the MDM Observatory and optical integral-field spectroscopy from SAURON, we explore the UV–line-strength relations of the 48 nearby early-type galaxies in the SAURON sample. Identical apertures are used for all quantities, avoiding aperture mismatch. We show that galaxies with purely old stellar populations show well-defined correlations of the integrated FUV −Vand FUV − NUV colours with the integrated Mgband Hβ absorption line-strength indices, strongest for FUV − NUV. Correlations with the NUV −Vcolour, Fe5015 index and stellar velocity dispersion σ are much weaker. These correlations put stringent constraints on the origin of the UV-upturn phenomenon in early-type galaxies and highlight its dependence on age and metallicity. In particular, despite recent debate, we recover the negative correlation between FUV −Vcolour and Mg line strength originally publicized by , which we refer to as the ‘Burstein relation’, suggesting a positive dependence of the UV upturn on metallicity. We argue that the scatter in the correlations is real and present mild evidence that a strong UV excess is preferentially present in slow-rotating galaxies. We also demonstrate that most outliers in the correlations are galaxies with current or recent star formation, some at very low levels. We believe that this sensitivity to weak star formation, afforded by the deep and varied data available for the SAURON sample, explains why our results are occasionally at odds with other recent but shallower surveys. This is supported by the analysis of a large, carefully crafted sample of more distant early-type galaxies from the Sloan Digital Sky Survey (SDSS), more easily comparable with current and future large surveys.