论文标题
清除II：在高红移处早期形成最紧凑的静态星系的证据
CLEAR II: Evidence for Early Formation of the Most Compact Quiescent Galaxies at High Redshift
论文作者
论文摘要
很难定义质量，形态，淬火分数和形成历史之间的相关性，这主要是由于星系星形成历史的不确定性。对于更高的红移星系，恒星形成历史可以更好地限制，观察到它们的形成和淬灭时代。在这里，我们使用“非参数”恒星形成历史和嵌套采样方法来得出对静态星系的形成和淬火时间尺度的约束，为$ 0.7 <z <z <2.5 $。我们对清晰的HST GRISM光谱和光度法进行了对清晰的（Candels Lyman $-α$排放）调查进行的测试。 Galaxy形成红移，$ z_ {50} $（定义为它们形成了恒星质量的50 \％）的范围从$ z_ {50} \ sim 2 $（在观察到的时代之前不久）到$ z_ {50} \ simeq 5-8 $。 \editone{We find that early formation redshifts are correlated with high stellar-mass surface densities, $\log Σ_1 / (M_\odot\ \mathrm{kpc}^{-2}) >$10.25, where $Σ_1$ is the stellar mass within 1~pkpc (proper kpc).具有最高恒星质量表面密度的静态星系，$ \logς_1 /（m_ \ odot \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 2 { - 2}）> 10.25 $，}显示A \ textit {mimumimum} cormitation {musimim} cormation redshift redshift：在我们的样本中：所有此类对象。表面密度较低的静态星系，$ \ logσ_1 /（m_ \ odot \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 2}^{ - 2}）= 9.5-10.25 $，显示一系列的地层时代（$ z_ {50} \ simeq 1.5-8 $），这些范围是一个范围的组合范围。我们认为表面密度阈值$ \logς_1/（m_ \ odot \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 2 { - 2}）> 10.25 $唯一地标识了大爆炸后前几个GYR中形成的星系，我们讨论了这对Galaxy形成模型的含义。
The origin of the correlations between mass, morphology, quenched fraction, and formation history in galaxies is difficult to define, primarily due to the uncertainties in galaxy star-formation histories. Star-formation histories are better constrained for higher redshift galaxies, observed closer to their formation and quenching epochs. Here we use "non-parametric" star-formation histories and a nested sampling method to derive constraints on the formation and quenching timescales of quiescent galaxies at $0.7<z<2.5$. We model deep HST grism spectroscopy and photometry from the CLEAR (CANDELS Lyman$-α$ Emission at Reionization) survey. The galaxy formation redshifts, $z_{50}$ (defined as the point where they had formed 50\% of their stellar mass) range from $z_{50}\sim 2$ (shortly prior to the observed epoch) up to $z_{50} \simeq 5-8$. \editone{We find that early formation redshifts are correlated with high stellar-mass surface densities, $\log Σ_1 / (M_\odot\ \mathrm{kpc}^{-2}) >$10.25, where $Σ_1$ is the stellar mass within 1~pkpc (proper kpc). Quiescent galaxies with the highest stellar-mass surface density, $\logΣ_1 / (M_\odot\ \mathrm{kpc}^{-2}) > 10.25$, } show a \textit{minimum} formation redshift: all such objects in our sample have $z_{50} > 2.9$. Quiescent galaxies with lower surface density, $\log Σ_1 / (M_\odot\ \mathrm{kpc}^{-2}) = 9.5 - 10.25$, show a range of formation epochs ($z_{50} \simeq 1.5 - 8$), implying these galaxies experienced a range of formation and assembly histories. We argue that the surface density threshold $\logΣ_1/(M_\odot\ \mathrm{kpc}^{-2})>10.25$ uniquely identifies galaxies that formed in the first few Gyr after the Big Bang, and we discuss the implications this has for galaxy formation models.
