SDSS-IV MaNGA : spatially resolved star formation histories in galaxies as a function of galaxy mass and type
SDSS-IV MaNGA : spatially resolved star formation histories in galaxies as a function of galaxy mass and type
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DOI：
10.1093/mnras/stw3371
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发表时间：
2016-12
影响因子：
4.8
通讯作者：
D. Goddard;D. Thomas;C. Maraston;K. Westfall;J. Etherington;R. Riffel;N. Mallmann;Zheng Zheng-Zheng
中科院分区：
文献类型：
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作者：
D. Goddard;D. Thomas;C. Maraston;K. Westfall;J. Etherington;R. Riffel;N. Mallmann;Zheng Zheng-Zheng
我们研究了来自 SDSS-IV MaNGA 整体场单元巡天的 721 个星系的代表性样本的 1.5 Re 范围内恒星族属性的内部梯度，这些星系的恒星质量范围在 109 M⊙ 和 1011.5 M⊙ 之间。通过使用我们的完整光谱拟合代码 FIREFLY，我们得出了轻质和质量加权的恒星族特性及其径向梯度，以及完整的恒星形成和金属富集历史。我们还量化了不同的恒星种群模型和全光谱拟合例程对导出的恒星种群特性和径向梯度测量的影响。在我们的分析中，我们发现早型和晚型星系的年龄梯度往往都很浅。早期型星系的质量加权年龄梯度为正[原文如此]（∼0.09 dex/Re），表明恒星形成是“从外到内”的过程，而晚期型星系具有负的轻权年龄梯度（∼−0.11 dex/Re），表明盘的形成是“从内到外”。我们在早期型和晚期型星系中检测到负金属丰度梯度，但这些梯度在早期型星系中明显更陡。晚期类型，表明化学富集过程的径向依赖性以及气体流入和金属传输的影响在圆盘中更为明显。两种形态类别的金属丰度梯度都与星系质量相关，负金属丰度梯度随着星系质量的增加而变得更陡。晚型星系与质量的相关性更强，其斜率为 d(∇[Z/H])/d(log M) ∼ −0.2 ± 0.05 ，而早型星系的斜率为 d(∇[Z/H])/d(log M) ∼ −0.05 ± 0.05。这一结果表明，合并历史在塑造星系金属丰度梯度方面发挥的作用相对较小。
We study the internal gradients of stellar population properties within 1.5 Re for a representative sample of 721 galaxies, with stellar masses ranging between 109 M⊙ and 1011.5 M⊙ from the SDSS-IV MaNGA Integral-Field-Unit survey. Through the use of our full spectral fitting code FIREFLY, we derive light- and mass-weighted stellar population properties and their radial gradients, as well as full star formation and metal enrichment histories. We also quantify the impact that different stellar population models and full spectral fitting routines have on the derived stellar population properties and the radial gradient measurements. In our analysis, we find that age gradients tend to be shallow for both early-type and late-type galaxies. Mass-weighted age gradients of early-types arepositive [sic] (∼0.09 dex/Re) pointing to ‘outside–in’ progression of star formation, while late-type galaxies have negative light-weighted age gradients (∼−0.11 dex/Re), suggesting an ‘inside–out’ formation of discs.We detect negative metallicity gradients in both early- and late-type galaxies, but these are significantly steeper in late-types, suggesting that the radial dependence of chemical enrichment processes and the effect of gas inflow and metal transport are far more pronounced in discs. Metallicity gradients of both morphological classes correlate with galaxy mass, with negative metallicity gradients becoming steeper with increasing galaxy mass. The correlation with mass is stronger for late-type galaxies, with a slope of d(∇[Z/H])/d(log M) ∼ −0.2 ± 0.05 , compared to d(∇[Z/H])/d(log M) ∼ −0.05 ± 0.05 for early-types. This result suggests that the merger history plays a relatively small role in shaping metallicity gradients of galaxies.