分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jiajun Zhang
Pablo Motta
Camila P. Novaes
Filipe B. Abdalla
Andre A. Costa
Bin Wang
Zhenghao Zhu
Chenxi Shan
Haiguang Xu
Elcio Abdalla
Luciano Barosi
Francisco A. Brito
Amilcar Queiroz
Thyrso Villela
Carlos A. Wuensche
Elisa G. M. Ferreira
Karin S. F. Fornazier
Alessandro Marins
Larissa Santos
Marcelo Vargas dos Santos
摘要： BINGO (Baryon Acoustic Oscillations from Integrated Neutral Gas Observations.) is a radio telescope designed to survey from 980 MHz to 1260 MHz, observe the neutral Hydrogen (HI) 21-cm line and detect BAO (Baryon Acoustic Oscillation) signal with Intensity Mapping technique. Here we present our method to generate mock maps of the 21-cm Intensity Mapping signal covering the BINGO frequency range and related test results. (Abridged)
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jiming Chen
Shamik Ghosh
Hao Liu
Larissa Santos
Wenjuan Fang
Siyu Li
Yang Liu
Hong Li
Jiaxin Wang
Le Zhang
Bin Hu
Wen Zhao
摘要： Constructing a fast and efficient estimator for the B-mode power spectrum of cosmic microwave background (CMB) is of critical importance for CMB science. For a general CMB survey, the Quadratic Maximum Likelihood (QML) estimator for CMB polarization has been proved to be the optimal estimator with minimal uncertainties, but it is computationally very expensive. In this article, we propose two new QML methods for B-mode power spectrum estimation. We use the Smith-Zaldarriaga approach to prepare pure-B mode map, and E-mode recycling method to obtain a leakage free B-mode map. We then use the scalar QML estimator to analyze the scalar pure-B map (QML-SZ) or B-mode map (QML-TC). The QML-SZ and QML-TC estimators have similar error bars as the standard QML estimators but their computational cost is nearly one order of magnitude smaller. The basic idea is that one can construct the pure B-mode CMB map by using the E-B separation method proposed by Smith-Zaldarriaga (SZ) or the one considering the template cleaning (TC) technique, then apply QML estimator to these scalar fields. By simulating potential observations of space-based and ground-based detectors, we test the reliability of these estimators by comparing them with the corresponding results of the traditional QML estimator and the pure B-mode pseudo-Cl estimator.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Alessandro Marins
Filipe B. Abdalla
Karin S. F. Fornazier
Elcio Abdalla
Luiz H. F. Assis
Mathieu Remazeilles
Carlos Alexandre Wuensche
Luciano Barosi
Amilcar R. Queiroz
Thyrso Villela
Bin Wang
Chang Feng
Ricardo Landim
Vincenzo Liccardo
Camila P. Novaes
Larissa Santos
Marcelo V. dos Santos
Jiajun Zhang
摘要： BINGO will observe hydrogen distribution by means of the 21 cm line signal by drift-scan mapping through a tomographic analysis called \emph{Intensity Mapping} (IM) between 980 and 1260 MHz which aims at analyzing Dark Energy using \emph{Baryon Acoustic Oscillations}. In the same frequency range, there are several other unwanted signals as well as instrumental noise, contaminating the target signal. There are many component separation methods to reconstruct signals. Here, we used just three blind methods (FastICA, GNILC and GMCA), which explore different ways to estimate foregrounds' contribution from observed signals from the sky. Subsequently, we estimate 21 cm signal from its mixing with noise. We also analyzed how different number of simulations affect the quality of the estimation, as well as the effect of the binning on angular power spectrum to estimate 21 cm from the mixing with noise. For the BINGO sky range and sensitivity and the foreground model considered in the current simulation, we find that the effective dimension of the foreground subspace leading to best results is equal to three, composed of non-physical templates. At this moment of the pipeline configuration, using 50 or 400 simulations is statistically equivalent. It is also possible to reduce the number of multipoles by half to speed up the process and maintain the quality of results. All three algorithms used to perform foreground removal yielded statistically equivalent results for estimating the 21cm signal when we assume 400 realizations and GMCA and FastICA's mixing matrix dimensions equal to three. However, concerning computational cost in this stage of the BINGO pipeline, FastICA is faster than other algorithms. A new comparison will be necessary when the time-ordered-data and map-making are available.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Shamik Ghosh
Yang Liu
Le Zhang
Siyu Li
Junzhou Zhang
Jiaxin Wang
Jiazheng Dou
Jiming Chen
Jacques Delabrouille
Mathieu Remazeilles
Chang Feng
Bin Hu
Zhi-Qi Huang
Hao Liu
Larissa Santos
Pengjie Zhang
Zhaoxuan Zhang
Wen Zhao
Hong Li
Xinmin Zhang
摘要： AliCPT is the first Chinese cosmic microwave background (CMB) experiment which will make the most precise measurements of the CMB polarization in the northern hemisphere. The key science goal for AliCPT is the detection of primordial gravitational waves (PGWs). It is well known that an epoch of cosmic inflation, in the very early universe, can produce PGWs, which leave an imprint on the CMB in form of odd parity $B$-mode polarization. In this work, we study the performance of the component separation and parameter estimation pipelines in context of constraining the value of the tensor-to-scalar ratio. Based on the simulated data for one observation season, we compare five different pipelines with different working principles. Three pipelines perform component separation at map or spectra level before estimating $r$ from the cleaned spectra, while the other two pipelines performs a global fit for both foreground parameters and $r$. We also test different methods to account for the effects of time stream filtering systematics. This work shows that our pipelines provide consistent and robust constraints on the tensor-to-scalar ratio and a consistent sensitivity $\sigma(r) \sim 0.02$. This showcases the potential of precise $B$-mode polarization measurement with AliCPT-1. AliCPT will provide a powerful opportunity to detect PGWs, which is complementary with various ground-based CMB experiments in the southern hemisphere.
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