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arXiv 2102.12494astro-ph.GA
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快、慢、早、晚:在z~0.8处淬灭大规模镓

Fast, Slow, Early, Late: Quenching Massive Galaxies at z~0.8

Sandro Tacchella, Charlie Conroy, S. M. Faber, Benjamin D. Johnson, Joel Leja, Guillermo Barro, Emily C. Cunningham, Alis J. Deason, Puragra Guhathakurta, Yiche… 展开作者

Sandro Tacchella, Charlie Conroy, S. M. Faber, Benjamin D. Johnson, Joel Leja, Guillermo Barro, Emily C. Cunningham, Alis J. Deason, Puragra Guhathakurta, Yicheng Guo, Lars Hernquist, David C. Koo, Kevin McKinnon, Constance M. Rockosi, Joshua S. Speagle, Pieter van Dokkum, Hassen M. Yesuf

摘要:

我们调查了161个大质量的样本,主要是静态星系在$\langle z_{\rm obs} \rangle=0.8$深凯克/DEIMOS静止框架光谱(HALO 7 D调查)的恒星种群。与完全贝叶斯框架探矿者,我们同时适合光谱和光度数据与先进的物理模型(包括非参数恒星形成的历史,发射线,可变的尘埃衰减规律,尘埃和活动星系核的排放)连同一个不确定性和离群值模型。我们表明,光谱学和光度学都需要打破尘埃年龄金属度简并。我们发现一个大的多样性的恒星形成的历史:虽然最大的质量($M_{\star}>2\times10^{11}~M_{\odot}$)星系形成最早(形成红移的$z_{\rm f}\approx5-10$与一个短的恒星形成时间尺度的$τ_{\rm SF}\lesssim1~\mathrm{Gyr}$),低质量的星系有一个广泛的形成红移,导致只有一个微弱的趋势$z_{\rm f}$与$M_{\star}$。有趣的是,几个低质量星系的形成红移为$z_{\rm f}\approx5-8$。恒星形成星系围绕恒星形成的主序演化,在它们的过去多次穿过山脊线。静止星系的猝灭时标($τ_{\rm quench}\approx0-5~\mathrm{Gyr}$)的中值为$\langleτ_{\rm quench}\rangle=1.0_{-0.9}^{+0.8}~\mathrm{Gyr}$,猝灭历元的中值为$z_{\rm quench}\approx0.8-5.0$($\langle z_{\rm quench}\rangle=1.3_{-0.4}^{+0.7}$)。淬灭时间尺度和时期的这种巨大多样性指向内部和外部淬灭机制的组合。在我们的样本中,返老还童和“大器晚成者”并不常见。总之,我们的分析支持“增长和淬火”的框架,并与广泛和持续填充的淬火时标的多样性是一致的。

英文摘要:

We investigate the stellar populations for a sample of 161 massive, mainly quiescent galaxies at $\langle z_{\rm obs} \rangle=0.8$ with deep Keck/DEIMOS rest-frame optical spectroscopy (HALO7D survey). With the fully Bayesian framework Prospector, we simultaneously fit the spectroscopic and photometric data with an advanced physical model (including non-parametric star-formation histories, emission lines, variable dust attenuation law, and dust and AGN emission) together with an uncertainty and outlier model. We show that both spectroscopy and photometry are needed to break the dust-age-metallicity degeneracy. We find a large diversity of star-formation histories: although the most massive ($M_{\star}>2\times10^{11}~M_{\odot}$) galaxies formed the earliest (formation redshift of $z_{\rm f}\approx5-10$ with a short star-formation timescale of $τ_{\rm SF}\lesssim1~\mathrm{Gyr}$), lower-mass galaxies have a wide range of formation redshifts, leading to only a weak trend of $z_{\rm f}$ with $M_{\star}$. Interestingly, several low-mass galaxies with have formation redshifts of $z_{\rm f}\approx5-8$. Star-forming galaxies evolve about the star-forming main sequence, crossing the ridgeline several times in their past. Quiescent galaxies show a wide range and continuous distribution of quenching timescales ($τ_{\rm quench}\approx0-5~\mathrm{Gyr}$) with a median of $\langleτ_{\rm quench}\rangle=1.0_{-0.9}^{+0.8}~\mathrm{Gyr}$ and of quenching epochs of $z_{\rm quench}\approx0.8-5.0$ ($\langle z_{\rm quench}\rangle=1.3_{-0.4}^{+0.7}$). This large diversity of quenching timescales and epochs points toward a combination of internal and external quenching mechanisms. In our sample, rejuvenation and "late bloomers" are uncommon. In summary, our analysis supports the "grow & quench" framework and is consistent with a wide and continuously-populated diversity of quenching timescales.

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