arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新，休息一下吧，周末愉快~~
arXiv 1707.03514astro-ph.CO
收藏

探测红移21厘米谱线圆偏振的原初引力波：II。预测

Detecting primordial gravitational waves with circular polarization of the redshifted 21 cm line: II. Forecasts

Abhilash Mishra, Christopher M. Hirata

备注：
19 pages, matches PRD accepted version
发表信息：
Phys. Rev. D 97, 103522 (2018)
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

在本系列的第一篇论文中，我们证明了在高红移的CMB四极导致发射的21 cm辐射的小圆偏振。本文预测了第一宇宙光时代（$z\sim 20$）未来射电实验测量CMB四极子的灵敏度。21厘米圆极化的层析测量，使我们能够构建一个三维远程四极场。测量该远程四极场的$B$模式分量可以用于对张量标量比$r$施加界限。我们费舍尔预测未来的快速傅里叶变换望远镜（FFTT），由一个阵列的偶极天线在一个紧凑的网格配置，作为阵列大小和观测时间的函数。我们发现边长为100 km的FFTT经过10年的观测可以达到$σ(r)\sim 4\times 10^{-3}$，并且天空覆盖范围为$f_{\mathrm{sky}}\sim 0.7$。预测是依赖于莱曼- $α$通量在预再电离时代的演变，这仍然是观测不受约束。最后，我们计算了典型的数量级的圆极化前景和评论他们的缓解策略。我们的结论是，检测原始引力波与21厘米的观测原则上是可能的，只要原始磁场振幅小，但需要一个非常未来的实验与相应的校准和前景抑制技术的进步。

英文摘要：

In the first paper of this series, we showed that the CMB quadrupole at high redshifts results in a small circular polarization of the emitted 21 cm radiation. In this paper we forecast the sensitivity of future radio experiments to measure the CMB quadrupole during the era of first cosmic light ($z\sim 20$). The tomographic measurement of 21 cm circular polarization allows us to construct a 3D remote quadrupole field. Measuring the $B$-mode component of this remote quadrupole field can be used to put bounds on the tensor-to-scalar ratio $r$. We make Fisher forecasts for a future Fast Fourier Transform Telescope (FFTT), consisting of an array of dipole antennas in a compact grid configuration, as a function of array size and observation time. We find that a FFTT with a side length of 100 km can achieve $σ(r)\sim 4\times 10^{-3}$ after ten years of observation and with a sky coverage $f_{\mathrm{sky}}\sim 0.7$. The forecasts are dependent on the evolution of the Lyman-$α$ flux in the pre-reionization era, that remains observationally unconstrained. Finally, we calculate the typical order of magnitudes for circular polarization foregrounds and comment on their mitigation strategies. We conclude that detection of primordial gravitational waves with 21 cm observations is in principle possible, so long as the primordial magnetic field amplitude is small, but would require a very futuristic experiment with corresponding advances in calibration and foreground suppression techniques.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑