GAMA巡天中宇宙计时器的识别
Identification of Cosmic Chronometers in the GAMA Survey
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中文总结 AI 辅助
本研究从GAMA巡天中选出231个高质量椭圆星系作为宇宙计时器候选体，通过NUVrJ测光、光谱特征及Ca II线比等严格筛选，确认其低恒星形成率和较老年龄，以提高H(z)和H0测量的稳健性。
中文摘要 AI 辅助
我们呈现了一个包含231个高质量、被动演化的椭圆星系的纯净样本，这些星系作为宇宙计时器候选体，选自星系与质量集合（GAMA）巡天，红移范围在$0.03<z<0.4$之间。本工作的目标是增加文献中可获得的高纯度宇宙计时器候选体的数量，并评估纯度对统计不确定性的影响，以使未来的$H(z)$和$H_0$计算更加稳健。我们使用传统的选择标准，结合测光和光谱数据以及诸如恒星质量和速度弥散等建模参数来识别宇宙计时器。我们采用NUVrJ测光选择来识别静止星系，并识别一系列光谱特征，包括H$\alpha$、[OII]和H$\delta$，作为正在进行或最近停止恒星形成的示踪物。此外，作为选择的一部分，我们计算Ca II H和K线的比率，以确定星系的恒星种群是由老年恒星还是年轻恒星主导。我们通过仅选择质量最大的星系来确认宇宙计时器的候选资格，并对候选体的光谱和图像进行目视检查。我们提供了母样本与宇宙计时器样本的对比分析，并确认宇宙计时器具有更低的比恒星形成率（sSFR），中值sSFR为$10^{-12}~\text{Myr}^{-1}$。此外，我们发现它们的中值年龄比母样本大约老$2~\text{Gyr}$。
英文摘要
We present a pure sample of 231 massive, passively evolving elliptical galaxies as cosmic chronometer candidates selected from the Galaxy and Mass Assembly (GAMA) survey between $0.03<z<0.4$. The goal of this work is to increase the pool of high-purity cosmic chronometer candidates available in the literature and assess the effect of purity on statistical uncertainty to make $H(z)$ and $H_0$ calculations more robust in future studies. We use traditional selection criteria to identify cosmic chronometers using photometry and spectroscopy in conjunction with modelled parameters such as stellar mass and velocity dispersion. We use an NUVrJ photometric selection to identify quiescent galaxies and identify a number of spectral features, including H$α$, [OII] and H$δ$ to use as tracers for ongoing or recently halted star formation. Additionally, as part of the selection, we calculate the ratio between the Ca II H and K lines to determine whether a galaxy's stellar population is dominated by older or younger stars. We confirm CC candidacy by selecting only the most massive galaxies and perform a visual inspection of the spectra and images of CC candidates. We provide an analysis of the parent sample in comparison to the CC sample and confirm CCs have much lower sSFR, with a median sSFR of $10^{-12}~\text{Myr}^{-1}$. Additionally, we find their median ages are $\sim2~\text{Gyr}$ older than the parent sample.
发表机构
- The Open University（开放大学）
- University of Hull（赫尔大学）
机构由 AI 辅助整理，请以论文原文为准。
