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arXiv 1803.02201astro-ph.GA
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z<0.05的星暴后星系的起源

The origins of post-starburst galaxies at z<0.05

Milena M. Pawlik, Layth Taj Aldeen, Vivienne Wild, Jairo Mendez-Abreu, Natalia Lahén, Peter H. Johansson, Noelia Jimenez, William Lucas, Yirui Zheng, C. Jakob W… 展开作者

Milena M. Pawlik, Layth Taj Aldeen, Vivienne Wild, Jairo Mendez-Abreu, Natalia Lahén, Peter H. Johansson, Noelia Jimenez, William Lucas, Yirui Zheng, C. Jakob Walcher, Kate Rowlands

摘要:

星暴后星系可以通过其光谱中显著的氢巴耳末吸收线来识别。本文用$0.01<z<0.05$、$\log(\mbox{M}_{\star}/\mbox{M}_{\odot})>9.5$和投影轴比$b/a>0.32$对189个有限体积的星系样本中强巴耳末线的起源进行了全面的研究。我们探索它们的结构特性,环境,发射线和恒星形成的历史,并将它们与恒星形成和静止星系的控制样本以及模拟星系合并进行比较。排除污染物,其中强巴耳末线最有可能是由尘埃星几何形状引起的,我们发现了三种不同的途径通过后星爆阶段的证据,大多数事件发生在中等密度环境中:(1)一个重大的破坏性事件,如富含气体的大合并,导致恒星暴和球状成分的增长,接着是恒星形成的淬灭(2)在$\log(\mbox{M}_{\star}/\mbox{M}_{\odot})>10.5$,蓝序星系中的随机恒星形成,导致微弱的爆发,随后返回蓝序(30%);(3)在$\log(\mbox{M}_{\star}/\mbox{M}_{\odot})>10.5$,静止星系的周期演化,通过微弱的星爆逐渐向红序的高质量端移动,可能是与较小的富气伴星(40%)合并的结果。我们的分析表明,活动星系核是“对”的$50%$的持续时间的后星暴阶段,这意味着传统的样品后星暴星系严格的发射线削减将至少$50%$不完整,由于排除窄线活动星系核。

英文摘要:

Post-starburst galaxies can be identified via the presence of prominent Hydrogen Balmer absorption lines in their spectra. We present a comprehensive study of the origin of strong Balmer lines in a volume-limited sample of 189 galaxies with $0.01<z<0.05$, $\log(\mbox{M}_{\star}/\mbox{M}_{\odot})>9.5$ and projected axis ratio $b/a>0.32$. We explore their structural properties, environments, emission lines and star formation histories, and compare them to control samples of star-forming and quiescent galaxies, and simulated galaxy mergers. Excluding contaminants, in which the strong Balmer lines are most likely caused by dust-star geometry, we find evidence for three different pathways through the post-starburst phase, with most events occurring in intermediate-density environments: (1) a significant disruptive event, such as a gas-rich major merger, causing a starburst and growth of a spheroidal component, followed by quenching of the star formation (70% of post-starburst galaxies at $9.5<\log(\mbox{M}_{\star}/\mbox{M}_{\odot})<10.5$ and 60% at $\log(\mbox{M}_{\star}/\mbox{M}_{\odot})>10.5$); (2) at $9.5<\log(\mbox{M}_{\star}/\mbox{M}_{\odot})<10.5$, stochastic star formation in blue-sequence galaxies, causing a weak burst and subsequent return to the blue sequence (30%); (3) at $\log(\mbox{M}_{\star}/\mbox{M}_{\odot})>10.5$, cyclic evolution of quiescent galaxies which gradually move towards the high-mass end of the red sequence through weak starbursts, possibly as a result of a merger with a smaller gas-rich companion (40%). Our analysis suggests that AGN are `on' for $50%$ of the duration of the post-starburst phase, meaning that traditional samples of post-starburst galaxies with strict emission line cuts will be at least $50%$ incomplete due to the exclusion of narrow-line AGN.

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