The SAMI Galaxy Survey: Using concentrated star formation and stellar population ages to understand environmental quenching
The SAMI Galaxy Survey: Using concentrated star formation and stellar population ages to understand environmental quenching
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SAMI 星系调查：利用集中的恒星形成和恒星种群年龄来了解环境猝灭
DOI：
10.1093/mnras/stac2428
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发表时间：
2022
影响因子：
4.8
通讯作者：
Medling, Anne M.
中科院分区：
文献类型：
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作者：
Croom, Scott M.;Bryant, Julia J.;Vaughan, Sam P.;Schaefer, Adam L.;D’Eugenio, Francesco;Barsanti, Stefania;Brough, Sarah;Lagos, Claudia del P.;Medling, Anne M.
我们利用当前恒星形成的空间分布和恒星群年龄与完整的SAMI星系调查研究环境猝灭。通过恒星形成浓度指数[C-index，定义为log10(r50, H α/r50, cont)]，我们将样本分为常规星系（C-index≥- 0.2）和恒星形成中心集中的星系（SF-concentrated;C-index < - 0.2）。集中的恒星形成是当前正在经历“由外而内”淬火的星系的潜在指标。我们的环境包括未分组的星系，低质量群（M200≤1012.5M⊙），高质量群（M200在1012.5-14M⊙范围内）和星系团（M200> 1014M⊙）。我们发现，随着光晕质量的增加，sf集中的星系的比例分别增加了9±2%、8±3%、19±4%和29±4%，分别为未分组星系、低质量星系群、高质量星系群和星系团。我们将这些结果解释为群体和集群中“由外而内”猝灭的证据。为了研究sf集中星系的猝灭时间尺度，我们使用全光谱拟合计算了轻加权年龄（AgeL）和质量加权年龄（AgeM），以及dn4000和h δ指数。我们假设在进入一个星系群或星系团之前，星系的平均年龄径向轮廓与未分组的规则星系相似。在大半径范围内（1-2Re），高质量星系群中sf集中的星系比未分组的规则星系年龄更大，年龄差为1.83±0.38 Gyr forAgeM和1.34±0.56 Gyr forAgeM。这表明，虽然“由外而内”的淬灭在群体中是有效的，但这个过程不会很快淬灭整个星系。相比之下，1-2Reof星系团中sf集中的星系与未分组的规则星系的年龄一致（agel的年龄差为0.19±0.21 Gyr， agem的年龄差为0.40±0.61 Gyr），表明淬灭过程一定是快速的。
We study environmental quenching using the spatial distribution of current star formation and stellar population ages with the full SAMI Galaxy Survey. By using a star formation concentration index [C-index, defined as log10(r50, H α/r50, cont)], we separate our sample into regular galaxies (C-index ≥−0.2) and galaxies with centrally concentrated star formation (SF-concentrated;C-index <−0.2). Concentrated star formation is a potential indicator of galaxies currently undergoing ‘outside-in’ quenching. Our environments cover ungrouped galaxies, low-mass groups (M200≤ 1012.5M⊙), high-mass groups (M200in the range 1012.5–14M⊙) and clusters (M200> 1014M⊙). We find the fraction of SF-concentrated galaxies increases as halo mass increases by 9 ± 2 per cent, 8 ± 3 per cent, 19 ± 4 per cent, and 29 ± 4 per cent for ungrouped galaxies, low-mass groups, high-mass groups, and clusters, respectively. We interpret these results as evidence for ‘outside-in’ quenching in groups and clusters. To investigate the quenching time-scale in SF-concentrated galaxies, we calculate light-weighted age (AgeL) and mass-weighted age (AgeM) using full spectral fitting, as well as theDn4000 andHδAindices. We assume that the average galaxy age radial profile before entering a group or cluster is similar to ungrouped regular galaxies. At large radius (1–2Re), SF-concentrated galaxies in high-mass groups have older ages than ungrouped regular galaxies with an age difference of 1.83 ± 0.38 Gyr forAgeLand 1.34 ± 0.56 Gyr forAgeM. This suggests that while ‘outside-in’ quenching can be effective in groups, the process will not quickly quench the entire galaxy. In contrast, the ages at 1–2Reof cluster SF-concentrated galaxies and ungrouped regular galaxies are consistent (difference of 0.19 ± 0.21 Gyr forAgeL, 0.40 ± 0.61 Gyr forAgeM), suggesting the quenching process must be rapid.