标题： 利用全域21厘米信号限制温暗物质和第三族恒星 显示英文标题

标题： Constraining Warm Dark Matter and Pop III stars with the Global 21-cm Signal

摘要： 即将进行的地面和空间实验可能具有足够的精度，通过星系际介质的全貌21厘米信号，对高红移恒星形成、再电离以及暗物质（DM）施加重要的限制。 在早期宇宙中，低质量暗物质晕的相对丰度很重要时，测量全貌信号将对由暗物质较高的遗留速度（温暗物质，或WDM）导致的结构形成阻尼施加限制，这比冷暗物质（CDM）的情况更为显著。 然而，这种阻尼可以通过改变恒星形成效率（SFE）来模仿，并且由于存在性质未知的第三族（Pop III）恒星而难以检测。 我们研究了这些各种情况及其与WDM质量参数的退化关系 $m_X$，使用费舍尔矩阵分析法。 我们研究了$m_X = 7$keV的情况以及一个将SFE作为晕质量强函数的恒星形成模型，并包括了该模型的几种变化形式，同时结合了三种不同的输入噪声水平；我们还使用了分子冷却阈值附近的最小晕气压温度。 我们发现，当似然函数仅包含第二族（Pop II）恒星时，对于所有模型和噪声水平，在68$\%$置信区间内，$m_X$被约束到$\sim 0.4$keV的不确定性。 当似然函数包含较弱的第三族（Pop III）恒星时，$m_X \sim 0.3$keV，并且如果第三族恒星形成相对高效，则$m_X \sim 0.1$keV的不确定性，同时有严格的第三族恒星形成参数约束。 我们的结果显示，全貌21厘米信号是WDM模型的一个有前景的试验台，即使在与天体物理参数存在强烈退化的情况下也是如此。 显示英文摘要

摘要： Upcoming ground and space-based experiments may have sufficient accuracy to place significant constraints upon high-redshift star formation, Reionization, and dark matter (DM) using the global 21-cm signal of the intergalactic medium. In the early universe, when the relative abundance of low-mass DM halos is important, measuring the global signal would place constraints on the damping of structure formation caused by DM having a higher relic velocity (warm dark matter, or WDM) than in cold dark matter (CDM). Such damping, however, can be mimicked by altering the star formation efficiency (SFE) and difficult to detect because of the presence of Pop III stars with unknown properties. We study these various cases and their degeneracies with the WDM mass parameter $m_X$ using a Fisher matrix analysis. We study the $m_X = 7$ keV case and a star-formation model that parametrizes the SFE as a strong function of halo mass and include several variations of this model along with three different input noise levels for the likelihood; we also use a minimum halo virial temperature for collapse near the molecular cooling threshold. We find that when the likelihood includes only Pop II stars, $m_X$ is constrained to an uncertainty of $\sim 0.4$ keV for all models and noise levels at 68$\%$ CI. When the likelihood includes weak Pop III stars, $m_X \sim 0.3$ keV, and if Pop III star formation is relatively efficient, $m_X \sim 0.1$ keV uncertainty, with tight Pop III star-formation parameter constraints. Our results show that the global 21-cm signal is a promising test-bed for WDM models, even in the presence of strong degeneracies with astrophysical parameters.