利用线强度映射交叉相关搜寻第三星族恒星
Searching for Population III stars with line intensity mapping cross-correlations
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中文总结 AI 辅助
本研究扩展LIM分析模型，结合SPHEREx等仪器模拟巡天，量化LIM信号对星族参数的敏感性，预测可约束第三星族恒星形成效率与IMF，指出需下一代仪器及SPHEREx与JWST协同研究。
中文摘要 AI 辅助
数十年来对单个星系中第三星族（Population III, Pop III）恒星的搜寻已发现少量潜在候选体，但仍无法对最低质量系统中首批恒星的人口统计学特征进行统计上可靠的表征。线强度映射（Line Intensity Mapping, LIM）是一种测量包括最暗源在内的整个星系群集体发射波动的观测技术，为特别适配第三星族时代提供了替代策略。随着SPHEREx卫星近期发射及多项互补LIM研究的快速发展，我们有望对高红移恒星形成位点施加首批LIM约束。本研究将LIM功率谱的分析模型Zeus21/oLIMpus扩展，纳入第三星族恒星及低金属丰度、顶部重初始质量函数（Initial Mass Function, IMF）的恒星形成诊断特征发射线（如Hα和HeII）。我们引入灵活框架估算仪器与巡天配置相关的测量不确定度，并将其应用于SPHEREx及潜在下一代仪器的模拟巡天中首批恒星的LIM信号研究。我们量化了LIM信号对第二星族（Pop II）与第三星族参数变化的敏感性，并预测了SPHEREx可对第三星族恒星形成效率（Star Formation Efficiency, SFE）和IMF形状施加的联合约束。研究发现，需下一代仪器才能全面勘测第三星族理论图景（包括“经典”与“奇异”第三星族模型），并确定支撑此类研究的设计改进。最后，我们开展费舍尔（Fisher）分析表征SPHEREx与詹姆斯·韦伯空间望远镜（JWST）的协同效应，表明有望对第三星族SFE及传统第三星族模型的扩展施加联合约束。
英文摘要
Decades of searches for Population III stars in individual galaxies have yielded a few potential candidates, but a statistically robust characterization of the demographics of the first stars in the lowest-mass systems remains elusive. Line intensity mapping (LIM), an observational technique that measures fluctuations in the aggregate emission from the entire galaxy population --- including the faintest sources --- offers an alternative strategy that is especially well-suited for the Pop III era. With the recent launch of SPHEREx and the rapid development of a number of complementary LIM studies, we are poised to place some of the first LIM constraints on sites of star formation at high-redshift. In this work, we expand an analytical model for LIM power spectra, Zeus21/oLIMpus, to include Pop III stars and the emission lines identified as diagnostic signatures of star formation with a low-metallicity, top-heavy IMF, such as H$α$ and HeII. We introduce a flexible framework to estimate the measurement uncertainties associated with instrument and survey configurations, and apply these to study LIM signatures of the first stars in mock surveys carried out with SPHEREx and potential next-generation instruments. We quantify the sensitivity of the LIM signal to variations in Pop II and III parameters and forecast joint limits that can be placed on the Pop III star formation efficiency (SFE) and IMF shape with SPHEREx. We find that next-generation instruments will be necessary to comprehensively survey the Pop III theoretical landscape --- both with respect to `classical' and `exotic' Pop III models --- and identify design improvements that will enable such studies. Finally, we carry out a Fisher analysis to characterize synergies between SPHEREx and JWST, suggesting that joint constraints on the Pop III SFE and extensions to conventional Pop III models may be within reach.
