Galaxy properties as revealed by MaNGA – I. Constraints on IMF and M*/L gradients in ellipticals
Galaxy properties as revealed by MaNGA – I. Constraints on IMF and M*/L gradients in ellipticals
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DOI：
10.1093/mnras/stz2414
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发表时间：
2019-04
影响因子：
4.8
通讯作者：
H. Domínguez Sánchez-H.-Domínguez Sánchez-2124244809;M. Bernardi;J. Brownstein;N. Drory;R. Sheth
中科院分区：
文献类型：
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作者：
H. Domínguez Sánchez-H.-Domínguez Sánchez-2124244809;M. Bernardi;J. Brownstein;N. Drory;R. Sheth
我们估算了椭圆(E)星系和S0星系的年龄、金属丰度、α元素丰度比和恒星初始质量函数(IMF)。我们叠加了光谱，并使用了各种单星布居合成模型来解释这些光谱中的吸收线强度。我们量化了这些特性如何在人群中变化，以及随着银河中心距离的变化。这篇论文是该系列的第一篇，基于z≤为0.08时的纯椭圆星系样本。我们证实了以前的工作，即具有最大光度(LR)和中心速度色散(σ0)的ES中的IMF似乎朝着它们的中心越来越重。对于这些星系，从中心区域到Re，恒星的质量与光比最多只减少了2倍。相比之下，对于较低的LR和σ0星系，国际货币基金组织较浅，中心区域的M*/LR类似于外围，尽管定量估计取决于对元素丰度梯度的假设。在估计M*和Mdyn时，对这些梯度的自我协调使两者很好地一致：梯度使Mdyn减少∼0.2Dex，而仅略微增加使用Kroupa IMF推断的M*。这是一种不同于最近文献中所遵循的M*-Mdyn差异的分辨率，在最近的文献中，通过在整个星系中采用Salpeter IMF来增加大质量星系的M*，而保持Mdyn不变。一篇配套的论文讨论了如果一个人把慢旋转子和快旋转子分开，恒星种群差异是如何更加明显的。
We estimate ages, metallicities, α-element abundance ratios, and stellar initial mass functions (IMFs) of elliptical (E) and S0 galaxies from the MaNGA-DR15 survey. We stack spectra and use a variety of single stellar population synthesis models to interpret the absorption line strengths in these spectra. We quantify how these properties vary across the population, as well as with galactocentric distance. This paper is the first of a series and is based on a sample of pure elliptical galaxies at z ≤ 0.08. We confirm previous work showing that IMFs in Es with the largest luminosity (Lr) and central velocity dispersion (σ0) appear to be increasingly bottom heavy towards their centres. For these galaxies the stellar mass-to-light ratio decreases at most by a factor of 2 from the central regions to Re. In contrast, for lower Lr and σ0 galaxies, the IMF is shallower and M*/Lr in the central regions is similar to the outskirts, although quantitative estimates depend on assumptions about element abundance gradients. Accounting self-consistently for these gradients when estimating both M* and Mdyn brings the two into good agreement: gradients reduce Mdyn by ∼0.2 dex while only slightly increasing the M* inferred using a Kroupa IMF. This is a different resolution of the M*–Mdyn discrepancy than has been followed in the recent literature where M* of massive galaxies is increased by adopting a Salpeter IMF throughout the galaxy while leaving Mdyn unchanged. A companion paper discusses how stellar population differences are even more pronounced if one separates slow from fast rotators.