Testing for calibration systematics in the EDGES low-band data using Bayesian model selection
Testing for calibration systematics in the EDGES low-band data using Bayesian model selection
复制标题
使用贝叶斯模型选择测试 EDGES 低频带数据中的校准系统
DOI：
10.1093/mnras/stz3388
复制
发表时间：
2019
影响因子：
4.8
通讯作者：
J. Pober
中科院分区：
文献类型：
--
作者：
P. Sims;J. Pober
宇宙黎明（CD），当第一批恒星和原星系开始形成时，通常预计会伴随着无线电频率的吸收特征。这一特征是由于这些第一批发光物体发射的莱曼 α 光子将星际氢气的 21 厘米激发温度与其动力学温度耦合在一起，从而驱动其相对于宇宙微波背景吸收的过程而产生的。这种吸收曲线的详细特性编码了有关 CD 物理的强大信息。最近，鲍曼等人。分析了 EDGES 低频段无线电天线的数据，发现了一个以 78 MHz 为中心的意外深度吸收剖面，这可能是对该特征的检测。他们的具体分析使用多项式前景模型、平坦高斯吸收曲线和白噪声模型来拟合他们的测量结果；我们认为，更准确的模型（包括详细的噪声模型并考虑合理校准误差的影响）对于描述 EDGES 数据集至关重要。我们对 EDGES 低频段数据集的模型进行了基于贝叶斯证据的比较，发现那些包含这些附加组件的模型绝对是首选。包含全局信号的数据的最佳拟合模型子集倾向于与标准宇宙学假设一致的振幅 (A < 209 mK)。然而，没有强有力的证据表明包含全球 21 厘米信号的数据模型优于不包含全球 21 厘米信号的数据模型。最终，我们发现从数据中推导天体物理学的稳健约束受到系统学的存在的限制。
Cosmic Dawn (CD), when the first stars and proto-galaxies began to form, is commonly expected to be accompanied by an absorption signature at radio frequencies. This feature arises as Lyman α photons emitted by these first luminous objects couple the 21 cm excitation temperature of intergalactic hydrogen gas to its kinetic temperature, driving it into absorption relative to the cosmic microwave background. The detailed properties of this absorption profile encode powerful information about the physics of CD. Recently, Bowman et al. analysed data from the EDGES low-band radio antenna and found an unexpectedly deep absorption profile centred at 78 MHz, which could be a detection of this signature. Their specific analysis fit their measurements using a polynomial foreground model, a flattened Gaussian absorption profile, and a white noise model; we argue that a more accurate model, that includes a detailed noise model and accounting for the effects of plausible calibration errors, is essential for describing the EDGES data set. We perform a Bayesian evidence-based comparison of models of the EDGES low-band data set and find that those incorporating these additional components are decisively preferred. The subset of the best-fitting models of the data that include a global signal favours an amplitude consistent with standard cosmological assumptions (A < 209 mK). However, there is not strong evidence to favour models of the data including a global 21 cm signal over those without one. Ultimately, we find that the derivation of robust constraints on astrophysics from the data is limited by the presence of systematics.
DOI：
10.1088/1538-3873/129/974/045001
发表时间：
2017-04-01
影响因子：
3.5
作者：
DeBoer, David R.;Parsons, Aaron R.;Zheng, Haoxuan
通讯作者：
Zheng, Haoxuan
影响因子：
6.5
作者：
van Haarlem, M. P.;Wise, M. W.;van Zwieten, J.
通讯作者：
van Zwieten, J.