Stellar Mass-to-Light Ratios and the Tully-Fisher Relation
Stellar Mass-to-Light Ratios and the Tully-Fisher Relation
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DOI：
10.1086/319728
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发表时间：
2000-08
期刊：
影响因子：
--
通讯作者：
E. Bell;R. D. de Jong
中科院分区：
文献类型：
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作者：
E. Bell;R. D. de Jong
我们用一套简化的光谱旋涡星系演化模型论证了星系内部和星系之间恒星质量/光比(M/L)存在很大的差异，在光学上是3-7倍，在近红外是2倍。我们的模型表明恒星的M/L与积分恒星群的光学颜色之间有很强的相关性。在宇宙旋涡星系初始质量函数的假设下，M/L恒星颜色模型的相对趋势对恒星数量和星系演化模型中的不确定性是稳健的，包括恒星形成的适度爆发的影响。尘埃变红估计中的误差不会强烈影响恒星群的最终导出恒星质量。我们用精确的自转曲线以及光学和近红外光度分布检验了一个旋涡星系样本的观测到的最大盘状恒星M/L比值。从这些观测到的最大盘M/L比，我们得出结论：Salpeter IMF在单位光度内有太多的低质量恒星，但类似于Salpeter IMF的大质量端低质量恒星较少(给出的恒星M/L比比Salpeter值低30%)符合最大盘限制。观测到的最大盘恒星M/L比值随颜色的变化趋势与预测的模型关系提供了很好的匹配，这表明螺旋星系恒星IMF是普遍存在的，部分(特别是高表面亮度)螺旋星系可能接近最大盘状星系。我们将恒星M/L比值随颜色变化的模型应用于Tully-Fisher(T-F)关系。我们发现，恒星质量T-F关系比较陡峭，具有适度的散射，并且与用于推导恒星质量的通带和颜色无关，这再次支持了通用的IMF。光学(特别是蓝色)和近红外T-F关系斜率的差异是尘埃衰减和恒星M/L随星系质量变化的综合作用的结果。假设哈勃太空望远镜的重点项目距离厄尔萨大星系团的距离，并忽略(不确定的)分子气体分数，我们发现，当使用平分线拟合和从旋转曲线的平坦部分导出的旋转速度时，重子T-F关系采用Mbaryon∝V3.5的形式(随机的和系统的1σ斜率误差为~0.2时)。由于我们已经将恒星的M/L比归一化为最大盘约束所能允许的最高值，如果所有的盘基本上都是次极大的，那么重子T-F关系的斜率将略低于3.5。
We have used a suite of simplified spectrophotometric spiral galaxy evolution models to argue that there are substantial variations in stellar mass-to-light (M/L) ratios within and among galaxies, amounting to factors of between 3 and 7 in the optical and factors of 2 in the near-infrared. Our models show a strong correlation between stellar M/L and the optical colors of the integrated stellar populations. Under the assumption of a universal spiral galaxy initial mass function (IMF), relative trends in model stellar M/L with color are robust to uncertainties in stellar population and galaxy evolution modeling, including the effects of modest bursts of star formation. Errors in the dust-reddening estimates do not strongly affect the final derived stellar masses of a stellar population. We examine the observed maximum disk stellar M/L ratios of a sample of spiral galaxies with accurate rotation curves and optical and near-infrared luminosity profiles. From these observed maximum disk M/L ratios we conclude that a Salpeter IMF has too many low-mass stars per unit luminosity but that an IMF similar to the Salpeter IMF at the high-mass end with less low-mass stars (giving stellar M/L ratios 30% lower than the Salpeter value) is consistent with the maximum disk constraints. Trends in observed maximum disk stellar M/L ratios with color provide a good match to the predicted model relation, suggesting that the spiral galaxy stellar IMF is universal and that a fraction of (particularly high surface brightness) spiral galaxies may be close to maximum disk. We apply the model trends in stellar M/L ratio with color to the Tully-Fisher (T-F) relation. We find that the stellar mass T-F relation is relatively steep, has modest scatter, and is independent of the passband and color used to derive the stellar masses, again lending support for a universal IMF. The difference in slope between the optical (especially blue) and near-infrared T-F relations is due to the combined effects of dust attenuation and stellar M/L variations with galaxy mass. Assuming the Hubble Space Telescope Key Project distance to the Ursa Major Cluster and neglecting the (uncertain) molecular gas fraction, we find that the baryonic T-F relation takes the form Mbaryon ∝ V3.5 (with random and systematic 1 σ slope errors of ~0.2 each) when using a bisector fit and rotation velocities derived from the flat part of the rotation curve. Since we have normalized the stellar M/L ratios to be as high as can possibly be allowed by maximum disk constraints, the slope of the baryonic T-F relation will be somewhat shallower than 3.5 if all disks are substantially submaximal.