The ATLAS3D Project - XXVIII. Dynamically driven star formation suppression in early-type galaxies
The ATLAS3D Project - XXVIII. Dynamically driven star formation suppression in early-type galaxies
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ATLAS3D 项目 - XXVIII。
DOI：
10.1093/mnras/stu570
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发表时间：
2014
影响因子：
4.8
通讯作者：
Davis T
中科院分区：
文献类型：
--
作者：
Davis T
我们基于广域红外巡天探测器 (WISE) 22 μm 和星系演化探测器远紫外线发射，对 ATLAS3D 样本的早期型星系 (ETG) 中的恒星形成率 (SFR) 进行了测量。我们将这些与从 12CO 和 Hidata 估计的气体质量结合起来，以便研究比以前更大的 ETG 样本中的恒星形成效率 (SFE)。我们首先重新校准（基于 WISE 数据）旧恒星群（在 Ksband 追踪）和 22 μm 光度之间的关系，使我们能够消除星周尘埃 22 μm 发射的贡献。然后我们继续研究 ETG 在 Kennicutt-Schmidt (KS) 关系中的位置。富含分子气体的 ETG 具有与正常螺旋星系中心相当的恒星形成表面密度，但它们系统地偏离 KS 关系，具有较低的 SFE 约 2.5 倍（与其他作者一致）。这种效应是由星系驱动的，其中大部分分子材料位于旋转曲线的上升部分，并且剪切力很高。我们在这里首次表明，尽管 ETG 中单位时间每单位气体质量形成的恒星数量较低，但每个自由落体时间形成的恒星数量似乎大致恒定。这种动力学关系周围的分散仍然与星系特性（例如内部区域势的形状）相关。这使我们认为，动力学特性（例如气体的剪切力或整体稳定性）可能是调节恒星形成并导致恒星形成关系的大部分分散的重要第二参数。
We present measurements of the star formation rate (SFR) in the early-type galaxies (ETGs) of the ATLAS3Dsample, based onWide-field Infrared Survey Explorer(WISE) 22 μm andGalaxy Evolution Explorerfar-ultraviolet emission. We combine these with gas masses estimated from12CO and Hidata in order to investigate the star formation efficiency (SFE) in a larger sample of ETGs than previously available. We first recalibrate (based onWISEdata) the relation between old stellar populations (traced atKsband) and 22 μm luminosity, allowing us to remove the contribution of 22 μm emission from circumstellar dust. We then go on to investigate the position of ETGs on the Kennicutt–Schmidt (KS) relation. Molecular gas-rich ETGs have comparable star formation surface densities to normal spiral galaxy centres, but they lie systematically offset from the KS relation, having lower SFEs by a factor of ≈2.5 (in agreement with other authors). This effect is driven by galaxies where a substantial fraction of the molecular material is in the rising part of the rotation curve, and shear is high. We show here for the first time that although the number of stars formed per unit gas mass per unit time is lower in ETGs, it seems that the amount of stars formed per free-fall time is approximately constant. The scatter around this dynamical relation still correlates with galaxy properties such as the shape of the potential in the inner regions. This leads us to suggest that dynamical properties (such as shear or the global stability of the gas) may be important second parameters that regulate star formation and cause much of the scatter around star formation relations.