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arXiv 2301.09653astro-ph.GAastro-ph.CO
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从VANDELS看被动星系1.0<z<1.4的恒星形成历史和质量-金属丰度关系的性质

The star formation history and the nature of the mass-metallicity relation of passive galaxies at 1.0<z<1.4 from VANDELS

Paolo Saracco, Francesco La Barbera, Roberto De Propris, Davide Bevacqua, Danilo Marchesini, Gabriella De Lucia, Fabio Fontanot, Michaela Hirschmann, Mario Noni… 展开作者

Paolo Saracco, Francesco La Barbera, Roberto De Propris, Davide Bevacqua, Danilo Marchesini, Gabriella De Lucia, Fabio Fontanot, Michaela Hirschmann, Mario Nonino, Anna Pasquali, Chiara Spiniello, Crescenzo Tortora

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18 pages + Appendix, 16 figures, 5 tables. Accepted for publication in MNRAS
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摘要：

我们计算了VANDELS巡天中选取的70个被动早型星系的恒星年龄和金属丰度[Z/H]，这些星系的红移范围为1.0 $\sim$ $z$ $<$ 1.4，恒星质量范围为10 $<$ log（M $_*$ /M $_\odot$）$<$ 11.6.我们发现显着的系统性，在他们的估计取决于模型和波长范围考虑。使用全谱拟合技术，我们发现，无论是[Z/H]和年龄的增加与当地ETG的质量。年龄和金属丰度敏感的光谱指数独立地证实了这些趋势。根据EMILES模型，我们发现67%的星系的[Z/H] $>$为0.0，对于log（M $_*$ /M $_\odot$）$>$ 11，这个百分比上升到90%，其中平均金属丰度为[Z/H]=0.17 $\pm$ 0.1。在类似和较低的红移下与均匀测量的比较没有显示出在红移范围0.0<z<1.4内的任何金属丰度演化。导出的恒星形成（SF）历史表明，早期形成的恒星质量分数随着星系质量的增加而增加。log（M $_*$ /M $_\odot$）$>$ 11.0的星系拥有[Z/H]>0.05的恒星群体，在早期（t $_{form}$ $<$ 2 Gyr）形成于短时间尺度（$Δ{t50}$ $<$ 1 Gyr），这意味着在高质量密度区域（log（$Σ_{1kpc}$）$>$ 10 M $_\odot$ /kpc $^2$）有很高的恒星形成率（SFR $>$ 100 M $_\odot$ /yr）。这个清晰的图像在较低质量时会变得模糊：log（M $_*$ /M $_\odot$）$\sim$ 10.6星系可以拥有[Z/H] $<$ 0.0的老恒星，也可以拥有[Z/H] $>$ 0.0的年轻恒星，这取决于SF的持续时间（$Δ{t50}$）。因此，星系质量、年龄和金属丰度之间的关系主要是作为星系形成过程的一部分从头开始建立的。质量、SFR和SF时间尺度都有助于形成恒星质量-金属丰度关系，质量调节金属的保留。

英文摘要：

We derived stellar ages and metallicities [Z/H] for $\sim$70 passive early type galaxies (ETGs) selected from VANDELS survey over the redshift range 1.0$<$$z$$<$1.4 and stellar mass range 10$<$log(M$_*$/M$_\odot$)$<$11.6. We find significant systematics in their estimates depending on models and wavelength ranges considered. Using the full-spectrum fitting technique, we find that both [Z/H] and age increase with mass as for local ETGs. Age and metallicity sensitive spectral indices independently confirm these trends. According to EMILES models, for 67 per cent of the galaxies we find [Z/H]$>$0.0, a percentage which rises to $\sim$90 per cent for log(M$_*$/M$_\odot$)$>$11 where the mean metallicity is [Z/H]=0.17$\pm$0.1. A comparison with homogeneous measurements at similar and lower redshift does not show any metallicity evolution over the redshift range 0.0<z<1.4. The derived star formation (SF) histories show that the stellar mass fraction formed at early epoch increases with the mass of the galaxy. Galaxies with log(M$_*$/M$_\odot$)$>$11.0 host stellar populations with [Z/H]>0.05, formed over short timescales ($Δ{t50}$$<$1 Gyr) at early epochs (t$_{form}$$<$2 Gyr), implying high star formation rates (SFR$>$100 M$_\odot$/yr) in high mass density regions (log($Σ_{1kpc}$)$>$10 M$_\odot$/kpc$^2$). This sharp picture tends to blur at lower masses: log(M$_*$/M$_\odot$)$\sim$10.6 galaxies can host either old stars with [Z/H]$<$0.0 or younger stars with [Z/H]$>$0.0, depending on the duration ($Δ{t50}$) of the SF. The relations between galaxy mass, age and metallicities are therefore largely set up ab initio as part of the galaxy formation process. Mass, SFR and SF time-scale all contribute to shape up the stellar mass-metallicity relation with the mass that modulates metals retention.

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