$z\sim$ 3.4 - 6.8层LAEs和LBG中恒星星族的差异和相似性
Differences and similarities of stellar populations in LAEs and LBGs at $z\sim$ 3.4 - 6.8
摘要：
LAE和LBG固有的恒星星族（SP）之间的差异是理解早期星系形成和演化的关键因素。我们对GOODS-N场高$z$吸收红色和死源（SHARDS）调查中的$3.4<z<6.8$的1,558个源样本运行了一组SP突发样模型。这项工作的重点是我们的样本的三个不同的观测亚族：LAE-LBG，无赖氨酸$α$ LBG和纯LAE之间的差异。单、双SP合成光谱用于模拟SED，采用贝叶斯信息准则分析在何种情况下需要第二SP。我们发现，源是很好的建模使用一个单一的SP在$\sim79\%$的情况下。最好的模型表明，纯LAE是典型的年轻低质量星系（$t\sim26^{+41}_{-25}$ Myr; $M_{\mathrm{star}}\sim5.6^{+12.0}_{-5.5}\times10^{8}\ M_{\odot}$），正在经历它们的第一次恒星形成爆发。另一方面，无Ly $α$ LBG需要较旧的SP（$t\sim71\pm12$ Myr），并且它们实质上更大质量（$M_{\mathrm{star}}\sim3.5\pm1.1\times10^{9}\ M_{\odot}$）。LAE-LBG似乎是更频繁地需要添加第二个SP的子组，代表了一个古老而巨大的星系，陷入了一个强大的近期恒星形成事件。在每个$z$中从每个亚家族发现的来源的相对数量支持从纯LAE和单SP LAE-LBG到更大规模LBG的进化场景。恒星的质量函数也得到了，发现随着宇宙时间的增加$M^{*}$和一个可能的陡峭的低质量的斜率从$z\sim6$ $z\sim5$没有显着的变化$z\sim4$。此外，我们还推导出了SFR- $M_{\mathrm{star}}$关系，发现了一个$\mathrm{SFR}\propto M_{\mathrm{star}}^β$行为，从$z\sim4$到$z\sim6$的演变可以忽略不计.
英文摘要：
The differences between the inherent stellar populations (SPs) of LAEs and LBGs are a key factor in understanding early galaxy formation and evolution. We have run a set of SP burst-like models for a sample of 1,558 sources at $3.4<z<6.8$ from the Survey for High-$z$ Absorption Red and Dead Sources (SHARDS) over the GOODS-N field. This work focuses on the differences between the three different observational subfamilies of our sample: LAE-LBGs, no-Ly$α$ LBGs and pure LAEs. Single and double SP synthetic spectra were used to model the SEDs, adopting a Bayesian information criterion to analyse under which situations a second SP is required. We find that the sources are well modelled using a single SP in $\sim79\%$ of the cases. The best models suggest that pure LAEs are typically young low mass galaxies ($t\sim26^{+41}_{-25}$ Myr; $M_{\mathrm{star}}\sim5.6^{+12.0}_{-5.5}\times10^{8}\ M_{\odot}$), undergoing one of their first bursts of star formation. On the other hand, no-Ly$α$ LBGs require older SPs ($t\sim71\pm12$ Myr), and they are substantially more massive ($M_{\mathrm{star}}\sim3.5\pm1.1\times10^{9}\ M_{\odot}$). LAE-LBGs appear as the subgroup that more frequently needs the addition of a second SP, representing an old and massive galaxy caught in a strong recent star-forming episode. The relative number of sources found from each subfamily at each $z$ supports an evolutionary scenario from pure LAEs and single SP LAE-LBGs to more massive LBGs. Stellar Mass Functions are also derived, finding an increase of $M^{*}$ with cosmic time and a possible steepening of the low mass slope from $z\sim6$ to $z\sim5$ with no significant change to $z\sim4$. Additionally, we have derived the SFR-$M_{\mathrm{star}}$ relation, finding a $\mathrm{SFR}\propto M_{\mathrm{star}}^β$ behaviour with negligible evolution from $z\sim4$ to $z\sim6$.
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