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arXiv 2004.13044astro-ph.GA
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近星系团恒星星族径向分布的最佳预测物理性质

The Most Predictive Physical Properties for the Stellar Population Radial Profiles of Nearby Galaxies

Guangwen Chen, Hong-Xin Zhang, Xu Kong, Zesen Lin, Zhixiong Liang, Xinkai Chen, Zuyi Chen, Zhiyuan Song

备注：
20 pages, 12 figures, ApJ in press
发表信息：
ApJ, 895, 146 (2020)
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摘要：

本文研究了3654个邻近星系的D4000、光度加权恒星年龄$τ_L$和光度加权恒星金属丰度$[Z/H]_L$的径向分布（$0.01<z<0.15$）使用SDSS DR 15中可用的MaNGA调查的IFU光谱数据，努力探索中值恒星星族径向梯度之间的联系（$\nabla$ D4000，$\nablaτ_L,\nabla[Z/H]_L$）到~ $1.5R_e$和各种星系性质，包括恒星质量（$M_\star$），比恒星形成率（sSFR），形态和局部环境。我们发现，$M_\star$是$\nabla$ D4000和$\nabla[Z/H]_L$的单一最具预测性的物理性质。$\nablaτ_L$最具预测性的特性是sSFR，其次是$M_\star$。环境参数，包括局部星系超密度和中心卫星分裂，与整个样本的恒星星族径向分布几乎没有相关性，但具有$M_\star\lesssim 10^{10}M_\odot$的恒星形成卫星星系的$\nabla$ D4000与星系超密度呈现显著的正相关性。具有较低sSFR的星系平均具有更陡峭的负恒星星族梯度，并且对于更大质量的恒星形成星系，这种sSFR依赖性更强。中等恒星星族梯度和$M_\star$之间的负相关性最好描述为分段关系，其中具有$\log M_\star\lesssim 10$的星系的中等梯度（精确值取决于sSFR）比具有较高$M_\star$的星系具有更弱的质量依赖性。虽然年龄和金属丰度的径向梯度对T型和中心恒星质量表面密度的依赖性通常不显着，但在本研究中探测的径向范围内，T型较晚或中心质量密度较低的星系往往具有显着较低的D4000，较年轻的$τ_L$和较低的$[Z/H]_L$。

英文摘要：

We present a study on the radial profiles of D4000,luminosity-weighted stellar ages $τ_L$,and luminosity-weighted stellar metallicities $[Z/H]_L$ of 3654 nearby galaxies($0.01<z<0.15$)using the IFU spectroscopic data from the MaNGA survey available in the SDSS DR15,in an effort to explore the connection between median stellar population radial gradients($\nabla$D4000,$\nablaτ_L,\nabla[Z/H]_L$)out to~$1.5R_e$ and various galaxy properties,including stellar mass($M_\star$),specific star formation rate(sSFR),morphologies,and local environment. We find that $M_\star$ is the single most predictive physical property for$\nabla$D4000 and$\nabla[Z/H]_L$. The most predictive properties for $\nablaτ_L$ are sSFR,and to a lesser degree,$M_\star$. The environmental parameters,including local galaxy overdensities and central-satellite division,have virtually no correlation with stellar population radial profiles for the whole sample,but the $\nabla$D4000 of star-forming satellite galaxies with$M_\star\lesssim 10^{10}M_\odot$exhibit a significant positive correlation with galaxy overdensities. Galaxies with lower sSFR have on average steeper negative stellar population gradients,and this sSFR dependence is stronger for more massive star-forming galaxies. The negative correlation between the median stellar population gradients and$M_\star$ are best described largely as segmented relationships, whereby median gradients of galaxies with$\log M_\star\lesssim 10$(with the exact value depending on sSFR)have much weaker mass dependence than galaxies with higher$M_\star$. While the dependence of the radial gradients of ages and metallicities on T-Types and central stellar mass surface densities are generally not significant,galaxies with later T-Types or lower central mass densities tend to have significantly lower D4000,younger$τ_L$ and lower$[Z/H]_L$ across the radial ranges probed in this study.

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