Title: Joint analysis constraints on the physics of the first galaxies with low frequency radio astronomy data Show Chinese title

Title: 第一 galaxies 物理学的联合分析约束与低频射电天文学数据

Abstract: The first billion years of cosmic history remains largely unobserved. We demonstrate, using a novel machine learning technique, how combining upper limits on the spatial fluctuations in the 21-cm signal with observations of the sky-averaged 21-cm signal from neutral hydrogen can improve our understanding of this epoch. By jointly analysing data from SARAS3 (redshift $z\approx15-25$) and limits from HERA ($z\approx8$ and $10$), we show that such a synergetic analysis provides tighter constraints on the astrophysics of galaxies 200 million years after the Big Bang than can be achieved with the individual data sets. Although our constraints are weak, this is the first time data from a sky-averaged 21-cm experiment and power spectrum experiment have been analysed together. In synergy, the two experiments leave only $64.9^{+0.3}_{-0.1}$% of the explored broad theoretical parameter space to be consistent with the joint data set, in comparison to $92.3^{+0.3}_{-0.1}$% for SARAS3 and $79.0^{+0.5}_{-0.2}$% for HERA alone. We use the joint analysis to constrain star formation efficiency, minimum halo mass for star formation, X-ray luminosity of early emitters and the radio luminosity of early galaxies. The joint analysis disfavours at 68% confidence a combination of galaxies with X-ray emission that is $\lesssim 33$ and radio emission that is $\gtrsim 32$ times as efficient as present day galaxies. We disfavour at $95$% confidence scenarios in which power spectra are $\geq126$ mK$^{2}$ at $z=25$ and the sky-averaged signals are $\leq-277$ mK. Show Chinese abstract

Abstract: 宇宙历史的前十亿年仍然 largely 未被观测。 我们展示了一种新的机器学习技术，如何结合21厘米信号的空间涨落上限与中性氢的天空平均21厘米信号观测，以改善我们对这一时期的理解。 通过联合分析SARAS3（红移$z\approx15-25$）的数据和HERA（$z\approx8$和$10$）的限制，我们表明这种协同分析比单独使用数据集能提供更严格的约束，以了解大爆炸后2亿年的星系天体物理。 尽管我们的约束较弱，但这是首次将天空平均21厘米实验和功率谱实验的数据一起分析。 协同作用下，这两个实验仅留下$64.9^{+0.3}_{-0.1}$% 的广泛理论参数空间，以与联合数据集一致，相比之下，SARAS3为$92.3^{+0.3}_{-0.1}$%，而HERA单独为$79.0^{+0.5}_{-0.2}$%。 我们利用联合分析来限制恒星形成效率、恒星形成的最小晕质量、早期发射器的X射线光度和早期星系的射电光度。 联合分析在68%置信度下不支持星系的X射线发射为当前星系的$\lesssim 33$倍且射电发射为当前星系的$\gtrsim 32$倍的组合。 我们在$95$%置信度下不支持功率谱在$z=25$处为$\geq126$mK$^{2}$，且天空平均信号为$\leq-277$mK的情况。