论文标题
SDSS-IV漫画:椭圆星系的全球和本地恒星种群特性
SDSS-IV MaNGA: global and local stellar population properties of elliptical galaxies
论文作者
论文摘要
我们使用漫画/SDSS-IV调查研究了343个椭圆星系的空间解析特性。我们将DESI传统成像调查用于形态学分类。基于集成的光谱特性和颜色,我们对七类椭圆形分类。我们将恒星年龄和金属性($ z $)梯度推断为1.5经典的“红色和死亡”,最近被淬火,以及蓝色的星形椭圆形(CLES,RQES和BSFS),分别对应于样品的73%,10%和4%。我们重建了他们的全球和径向恒星形成和质量增长的历史。我们发现CLE的质量加权年龄梯度几乎是平坦的或轻度的。相应的$ z $梯度为负,因为质量较小,因此要平坦。比较少的群体更早地形成恒星,淬火速度更快。 cles的内而外的生长和清晰的内而外。他们完成了全球淬火3.8 $ \ pm $ 1.2 GYR前,淬火时间尺度为3.4 $ \ pm $ 0.8 GYR。在Masses <10 $^{11} $ $ M _ {\ bigodot} $上,RQE和BSF的年龄和$ z $梯度比CLES的梯度更平整,但具有更大的分散。它们显示出非常弱的内而外的增长和淬火,这很慢,甚至在BSF的$ z \ sim0 $中都没有完成。取而代之的是,大规模的RQE在发光性加权年龄和出色的金属性中显示出外部的淬火和正梯度。所有群众的RQE平均在1.2 $ \ pm $ 0.9 GYR中淬灭。我们对CLE的结果与两阶段的情况一致,在这种情况下,它们的内部部分是由早期和同时的耗散性崩溃形成的,随之而来的恒星形成并进一步淬灭,而外部部件可能会由干燥的合并来延伸。我们还讨论了RQE和BSF星系的一些进化场景。
We study the spatially resolved properties of 343 elliptical galaxies with the MaNGA/SDSS-IV survey. We used the DESI Legacy Imaging Surveys for morphological classification. Based on integrated spectroscopic properties and colors, we classified seven classes of ellipticals. We inferred the stellar age and metallicity ($Z$) gradients out to a 1.5 effective radius of classical "red and dead", recently quenched, and blue star-forming ellipticals (CLEs, RQEs, and BSFs), corresponding to 73%, 10%, and 4% of the sample, respectively. We reconstructed their global and radial histories of star formation and mass growth. We find the mass- and luminosity-weighted age gradients of CLEs are nearly flat or mildly negative. The respective $Z$ gradients are negative, being flatter as the mass is smaller. The more massive CLEs formed stars earlier and quenched faster than the less massive ones. The CLEs show a weak inside-out growth and a clear inside-out quenching. They finished their quenching globally 3.8 $\pm$ 1.2 Gyr ago, with quenching time-scales of 3.4 $\pm$ 0.8 Gyr. At masses < 10$^{11}$ $M_{\bigodot}$, the age and $Z$ gradients of the RQEs and BSFs are flatter than those of the CLEs but with larger scatters. They show very weak inside-out growth and quenching, which is slow and even not completed at $z\sim0$ for the BSFs. Instead, the massive RQEs show an outside-in quenching and positive gradients in the luminosity-weighted age and stellar metallicities. The RQEs of all masses quenched 1.2 $\pm$ 0.9 Gyr ago on average. Our results for the CLEs are consistent with a two-phase scenario where their inner parts formed by an early and coeval dissipative collapse with a consequent burst of star formation and further quenching, whereas the outer parts continued their assembly likely by dry mergers. We also discuss some evolutionary scenarios for the RQE and BSF galaxies.