评估通过光度法选择的高红移星系样本中的超冷矮星污染
Assessing Ultra-Cool Dwarf Contamination in Photometrically Selected High-Redshift Galaxy Samples
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中文总结 AI 辅助
研究高红移星系样本中超冷矮星污染问题，开发FC-ENZO代码预测误判恒星数量，比较光谱库，发现污染分数与金属丰度等有关，为 survey 设计和光谱后续观测提供工具。
中文摘要 AI 辅助
超冷矮星（UCDs）是高红移星系搜索中常见的污染源，标准选择技术无法完全消除。我们开发了FC-ENZO代码，它能预测给定测量设置下被误识别为高红移星系的矮星数量。比较了两个光谱能量分布库，发现污染分数与金属丰度等有关，FC-ENZO为测量设计等提供了实用工具。
英文摘要
Ultra-cool dwarf stars (UCDs) are a common source of contamination in high-redshift galaxy searches because both populations have red colors and these early-forming galaxies can have sizes that are difficult to resolve even with space telescopes. We develop \textbf{F}oreground \textbf{C}ontamination \textbf{E}valuator of \textbf{N}earby dwarf stars in high-\textbf{Z} photometrically selected \textbf{O}bjects (FC-ENZO), a code that predicts magnitude-dependent UCD contamination for a given survey setup and galaxy selection method. FC-ENZO combines UCD number-density models, synthetic spectral libraries, and photometric selection criteria to estimate contaminant populations. We find that the predicted contamination is sensitive to the adopted UCD spectral model, stellar metallicity, and Galactic distribution models, with the Galactic distribution model producing variations of up to several factors. The Elf Owl models predict higher contamination than the Bobcat models, primarily because of their broader coverage of T and Y dwarf spectra. The dominant contaminants are late L to early Y-type UCDs, which are most commonly misclassified as galaxies at $z \sim 8$. For surveys with similar areas, broad-band observations from different space telescopes produce comparable numbers of contaminants at a given redshift, but contaminants are concentrated near the survey limiting magnitude, resulting in higher bright-end contamination fractions for shallower surveys. Adding medium-band filters can reduce the UCD contamination rate at $z\sim8$ by a factor of a few. At $z\gtrsim30$, F356W dropout selections can suffer substantial contamination from Y dwarfs. FC-ENZO provides a practical tool for survey design and for identifying fields suitable for spectroscopic follow-up.
发表机构
- National Astronomical Research Institute of Thailand (NARIT)（泰国国家天文研究所）
- Tohoku University（东北大学）
- School of Physics, The University of Melbourne（墨尔本大学物理学院）
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