论文标题
来自超跨型Minihalos的21厘米信号作为原始小规模波动的探测
The 21-cm signals from ultracompact minihalos as a probe of primordial small-scale fluctuations
论文作者
论文摘要
如果暗物质的密度波动在小尺度上显着幅度明显很大，则在物质辐射平等时期之后可以形成超级压缩的Minihalos〜（UCMHS）。对UCMH丰度的限制使我们能够访问如此小规模的波动。在本文中，我们介绍了通过测量21厘米的波动，在电离时代之前，我们可以获得对UCMH丰度的限制。我们从UCMHS计算21 cm信号，并表明UCMHS提供了21 cm波动的增强。我们还研究了对UCMH丰度和小规模曲率扰动的限制。我们的结果表明，即将到来的21厘米观察值平方公里阵列（SKA）提供了对原始曲率功率谱的振幅的约束，$ {\ cal a} _面_面\ sillsim 10^{ - 6} $ on $ 100〜 {\ rm mpc}^{\ rm mpc}^{ - 1} mpc}^{ - 1} $。尽管它并不比UCMHS中暗物质歼灭引起的γ射线的未检测的强度强，但SKA的约束将很重要，因为此约束与暗物质粒子模型无关。
Ultracompact minihalos~(UCMHs) can form after the epoch of matter-radiation equality, if the density fluctuations of dark matter have significantly large amplitude on small scales. The constraint on the UCMH abundance allows us to access such small-scale fluctuations. In this paper, we present that, through the measurement of 21-cm fluctuations before the epoch of reionization~ we can obtain a constraint on the UCMH abundance. We calculate the 21-cm signal from UCMHs and show that UCMHs provide the enhancement of the 21-cm fluctuations. We also investigate the constraint on the UCMH abundance and small-scale curvature perturbations. Our results indicate that the upcoming 21-cm observation, the Square Kilometre Array (SKA), provides the constraint on amplitude of primordial curvature power spectrum, ${\cal A}_ζ \lesssim 10^{-6}$ on $100~{\rm Mpc}^{-1} \lesssim k \lesssim 1000~{\rm Mpc}^{-1}$. Although it is not stronger than the one from the non-detection of gamma rays induced by dark matter annihilation in UCMHs, the constraint by the SKA will be important because this constraint is independent of the dark matter particle model.
