论文标题
漫画早期型星系的恒星种群分析：IMF依赖性和系统效应
Stellar population analysis of MaNGA early-type galaxies: IMF dependence and systematic effects
论文作者
论文摘要
我们研究与估计简单恒星种群（SSP）参数相关的系统学 - 年龄，金属性[m/h]，$α$ - 增强[$α$/fe]和IMF形状 - 以及相关的$ M _*/l $梯度，椭圆慢旋转器（E-SRS），快速旋转器（E-FRS）和s sepsce seppect seppect in seppect in Carlax ins compect in comport in seppect。这些系统学来自（i）在堆叠时如何使光谱归一化； （ii）在估计吸收线强度之前必须减去排放； （iii）决定适合整个光谱或仅几个吸收系的决定； （iv）SSP模型差异（例如等地线，富集，IMF）。 The MILES+Padova SSP models, fit to the H$_β$, $\langle$Fe$\rangle$, TiO$_{\rm 2SDSS}$ and [MgFe] Lick indices in the stacks, indicate that out to the half-light radius $R_e$: (a) ages are younger and [$α$/Fe] values are lower in the central regions but the opposite is true of [m/h]; （b）IMF在中心更底部，但靠近$ r_e/2 $的kroupa; （c）这使$ m _*/l $在中央区域大约$ 2 \ times $大于$ r_e/2 $。而Conroy等人的模型。 （2018）返回类似的[m/h]和[$α$/fe]概况，即使太阳丰度和kroupa imf，年龄及其$ m _*/l $ profiles也可能有很大差异；对非 - 极性丰度和IMF参数化的不同反应进一步加剧了这些差异。 E-SR，E-FRS和S0S之间存在明显的（独立的）差异：年轻年龄和较小的增强[$α$/Fe]值表明E-FRS和S0不是SSP，但是放松此假设不太可能改变其推断的$ M _*/L $梯度。
We study systematics associated with estimating simple stellar population (SSP) parameters -- age, metallicity [M/H], $α$-enhancement [$α$/Fe] and IMF shape -- and associated $M_*/L$ gradients, of elliptical slow rotators (E-SRs), fast rotators (E-FRs) and S0s from stacked spectra of galaxies in the MaNGA survey. These systematics arise from (i) how one normalizes the spectra when stacking; (ii) having to subtract emission before estimating absorption line strengths; (iii) the decision to fit the whole spectrum or just a few absorption lines; (iv) SSP model differences (e.g. isochrones, enrichment, IMF). The MILES+Padova SSP models, fit to the H$_β$, $\langle$Fe$\rangle$, TiO$_{\rm 2SDSS}$ and [MgFe] Lick indices in the stacks, indicate that out to the half-light radius $R_e$: (a) ages are younger and [$α$/Fe] values are lower in the central regions but the opposite is true of [M/H]; (b) the IMF is more bottom-heavy in the center, but is close to Kroupa beyond about $R_e/2$; (c) this makes $M_*/L$ about $2\times$ larger in the central regions than beyond $R_e/2$. While the models of Conroy et al. (2018) return similar [M/H] and [$α$/Fe] profiles, the age and (hence) $M_*/L$ profiles can differ significantly even for solar abundances and a Kroupa IMF; different responses to non-solar abundances and IMF parametrization further compound these differences. There are clear (model independent) differences between E-SRs, E-FRs and S0s: younger ages and less enhanced [$α$/Fe] values suggest that E-FRs and S0s are not SSPs, but relaxing this assumption is unlikely to change their inferred $M_*/L$ gradients significantly.
