Understanding Polarized Foreground from Dust: Towards Reliable Measurements of CMB Polarization
Alex Lazarian, Dan Clemens, Andy Adamson, B. -G. Andersson, David Axon, James De Buizer, Alberto Cellino, Dean C. Hines, Jennifer L. Hoffman, Terry Jay Jones, Antonio Mario Magalhaes, Joseph Masiero, Chris Packham, Marshall Perrin, Claudia Vilega Rodrigues, Hiroko Shinnaga, William Sparks, John Vaillancourt, Doug Whittet
未来十年宇宙学领域中关于光学/红外偏振测量的科学机会和建议。为响应对这类文件的呼吁，向Astro 2010提交了以社区为基础的白皮书。
Science opportunities and recommendations concerning optical/infrared polarimetry for the upcoming decade in the field of cosmology. Community-based White Paper to Astro2010 in response to the call for such papers.
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。
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CMB foregrounds consist of all radiation between the surface of last scattering and the detectors, which can interfere with the cosmological interpretation of CMB data. Fortunately, in temperature (intensity), even though the foregrounds are complex they can relatively easily be mitigated. However, in polarization, diffuse Galactic radiation (synchrotron and thermal dust) can be polarized at a level of >10 % making it more of a challenge. In particular, CMB B-modes, which are a smoking-gun signature of inflation, will be dominated by foregrounds. Component separation will therefore be critical…
Next generation CMB experiments such as CMB-S4 aim at measuring the CMB lensing potential at sub-percent precision where most of the constraining power will come from CMB polarization. We investigate the prospects of achieving this goal in the presence of large-scale, diffuse galactic foreground emission by using non-Gaussian sky simulations and exploit multi-frequency information to clean those. We show that, while prior to foreground cleaning, cosmological parameter estimates from the contaminated lensing potential estimation can be significantly biased, these can be successfully mitigated b…
A promising way to measure the distribution of matter on small scales (k ~ 10 hMpc^-1) is to use gravitational lensing of the Cosmic Microwave Background (CMB). CMB-HD, a proposed high-resolution, low-noise millimeter survey over half the sky, can measure the CMB lensing auto spectrum on such small scales enabling measurements that can distinguish between a cold dark matter (CDM) model and alternative models designed to solve problems with CDM on small scales. However, extragalactic foregrounds can bias the CMB lensing auto spectrum if left untreated. We present a foreground mitigation strateg…
Extracting CMB B-mode polarization from complicated foregrounds is a challenging task in searching for inflationary gravitational waves. We propose the ABS method as a blind and analytical solution to this problem. It applies to the measured cross bandpower between different frequency bands and obtains the CMB B-mode bandpower analytically. It does not rely on assumptions of foregrounds and does not require multiple parameter fitting. Testing against a variety of foregrounds, survey frequency configurations and instrument noise, we verify its applicability and numerical stability. The ABS meth…
In this paper, we try to probe whether a clean CMB map obtained from the raw satellite data using a cleaning procedure is sufficiently clean. Specifically we study if there are any foreground residuals still present in the cleaned data using a cross-correlation statistic. Residual contamination is expected to be present, primarily, in the galactic plane due to the high emission from our own galaxy. A foreground mask is applied conventionally to avoid biases in the estimated quantities of interest due to foreground leakage. Here, we map foreground residuals, if present, in the unmasked region i…
Polarized CMB Foregrounds: What do we know and how bad is it?
偏振前景将是探测CMB宇宙学B模的一个严峻挑战。在大角度尺度上，弥散的银河辐射和河外源都对功率谱有显著的贡献。在低频率，银河系同步辐射将占主导地位的分数极化$\sim 20-40%$在高纬度地区，而无线电源可以作出显着的贡献，即使在大（$\sim 1^{\circ}$）角尺度。然而，模拟表明，如果前景不是太复杂，则在$r=0.001$级别的检测是可以实现的。
We present a new approach to component separation in multifrequency CMB experiments by formulating the problem as that of partitioning the sky into pixel clusters such that within each pixel cluster the foregrounds have similar spectrum, using only the information available in the data. Only spectral information is used for partitioning, allowing spatially far away pixels to belong to the same cluster if their foreground properties are close. We then apply a modified internal linear combination method to each pixel cluster. Since the foregrounds have similar spectrum within each cluster, the n…
Dark matter search with CMB: a study of foregrounds
本文基于下一代地基CMB实验设计构建完整CMB数据与前景模拟，分析温度和偏振图对暗物质参数的灵敏度，发现前景残留使能量注入约束最多减弱19%，但仍可对暗物质湮灭率和衰变寿命给出强限制。
A Foreground Cleaned CMB Map from Non-Gaussianity Measurement
在本文中，我们提出了一种新的方法来估计前景清洁宇宙微波背景（CMB）地图的分辨率为$1^\circ$，通过最小化的非高斯性质的清洁地图，主要是由于扩散前景发射成分从银河系。我们采用简单的峰度统计作为非高斯特性的测量，并执行威尔金森微波各向异性探测器（WMAP）在其7年的数据发布中提供的5个频率图的线性组合，以这种方式，清洁的地图具有最小的峰度，这导致非高斯最小化，前景清洁CMB地图。我们通过进行蒙特卡罗模拟来验证该方法。为了最大限度地减少任何残留的前景污染，从清洁的地图，我们标记出区域附近的银河系平面的基础上，从模拟的结果。在掩蔽区域之外，我们对CMB图的新估计与WMAP的ILC图匹配良好。一个简单的伪$C_l$为基础的CMB TT功率谱的非高斯最小化的地图再现了WMAP的功率谱的早期结果。{ \it该方法的一个重要优点是在低多极区角功率谱中不引入任何负偏置，这与通常的ILC方法不同。}比较我们的结果与以前发表的结果，我们认为，CMB的结果是强大的特定前景去除算法。
Foreground removal techniques for CMB analyses make specific assumptions about the properties of foregrounds in temperature and in polarization. By investigating the statistics of foreground components more understanding about the degree to which these assumptions are valid can be obtained. In this work we investigate $E$- and $B$-mode maps of the two strongest polarized foregrounds, synchrotron and thermal dust emission, with regards to their similarity with Gaussian processes, their spectral variations and cross-correlations. We perform tests in patches of $\sim3.7^\circ$ size collectively c…
Extragalactic foregrounds are known to generate significant biases in temperature-based CMB lensing reconstruction. Several techniques, which include ``source hardening'' and ``shear-only estimators'' have been proposed to mitigate contamination and have been shown to be very effective at reducing foreground-induced biases. Here we extend both techniques to polarization, which will be an essential component of CMB lensing reconstruction for future experiments, and investigate the ``large-lens'' limit analytically to gain insight on the origin and scaling of foreground biases, as well as the se…
Internal Linear Combination (ILC) methods are some of the most widely used multi-frequency cleaning techniques employed in CMB data analysis. These methods reduce foregrounds by minimizing the total variance in the coadded map (subject to a signal-preservation constraint), although often significant foreground residuals or biases remain. A modification to the ILC method is the constrained ILC (cILC), which explicitly nulls certain foreground components; however, this foreground nulling often comes at a high price for ground-based CMB datasets, with the map noise increasing significantly on sma…
Faraday Rotation as a diagnostic of Galactic foreground contamination of CMB maps
来自前景残差的贡献可以对宇宙微波背景（CMB）的温度图产生显著影响。大多数情况下，焦点一直在银河平面上，当前景清理发生时。然而，在本文中，我们将调查可能的前景污染，从银河系以外的来源在CMB地图。我们将分析法拉第旋转图和CMB温度图之间的相关性。法拉第旋转图依赖于银河系的磁场，以及热电子密度，两者都可能有助于CMB温度。我们发现，平均互相关的标准差偏离模拟在99.9%的水平。此外，CMB温度极值和法拉第旋转的极值点之间的比较也被执行，显示两者之间的一般重叠。我们还发现CMB冷点位于一个强负相关的区域，这意味着它可以用银河系起源来解释。此外，我们调查附近的超新星遗迹在银河系中，跟踪银河无线电环路。这些超新星遗迹位于银河系的高纬度和低纬度，因此远远超出了银道面。我们发现法拉第旋转和CMB温度之间的一些相关性，在选择无线电环路。这表明，银河系前景可能会影响CMB，在银河系高纬度地区
Pixel domain implementation of the Minimally Informed CMB MAp foreground Cleaning method
本文提出一种非参数最大似然CMB清理方法的像素域新实现，扩展了对前景空间变异性的处理，验证表明其在复杂前景下优于参数化方法，是极具竞争力的替代方案。
The measurement of the large-scale B-mode polarization in the cosmic microwave background (CMB) is a fundamental goal of future CMB experiments. However, because of unprecedented sensitivity, future CMB experiments will be much more sensitive to any imperfect modelling of the Galactic foreground polarization in the reconstruction of the primordial B-mode signal. We compare the sensitivity to B-modes of different concepts of CMB satellite missions (LiteBIRD, COrE, COrE+, PRISM, EPIC, PIXIE) in the presence of Galactic foregrounds. In particular, we quantify the impact on the tensor-to-scalar pa…
In order to extract information about inflationary gravitational waves using $B$-mode patterns of cosmic microwave polarization anisotropy, we need to remove the foreground radiation from the Milky Way. In our previous delta-map method for foreground removal, the number of observation bands was limited to the number of parameters of the assumed foreground model, and therefore it was difficult to improve the sensitivity by increasing the number of observation bands. Here, we extend the previous method so that it can be adapted to an arbitrary number of observation bands. Using parametric likeli…
CMB lensing from current and upcoming wide-field CMB experiments such as AdvACT, SPT-3G and Simons Observatory relies heavily on temperature (vs. polarization). In this regime, foreground contamination to the temperature map produces significant lensing biases, which cannot be fully controlled by multi-frequency component separation, masking or bias hardening. In this letter, we split the standard CMB lensing quadratic estimator into a new set of optimal "multipole" estimators. On large scales, these multipole estimators reduce to the known magnification and shear estimators, and a new shear B…
We present a new, semi-analytic framework for estimating the level of residuals present in CMB maps derived from multi-frequency Cosmic Microwave Background (CMB) data and forecasting their impact on cosmological parameters. The data are assumed to contain non-negligible signals of astrophysical and/or Galactic origin, which we clean using parametric component separation technique. We account for discrepancies between the foreground model assumed during the separation procedure and the true one, allowing for differences in scaling laws and/or their spatial variations. Our estimates and their u…
Are CMB derived cosmological parameters affected by foregrounds associated to nearby galaxies?
本文通过掩蔽Planck CMB图中与近邻旋涡星系相关的新前景，发现其与局域参数变化呈3σ显著相关，但全天宇宙学参数保持不变。
Understanding large-angular-scale galactic foregrounds is crucial for future CMB experiments aiming to detect $B$-mode polarization from primordial gravitational waves. Traditionally, the dust component has been separated using its different frequency dependence. However, using non-CMB observations has potential to increase fidelity and decrease the reconstruction noise. In this exploratory paper we investigate the capability of galactic 21 cm observations to predict the dust foreground in intensity. We train a neural network to predict the dust foreground as measured by the Planck Satellite f…
Blind mitigation of foreground-induced biases on primordial $B$ modes for ground-based CMB experiments
本文提出两种改进NILC框架的方法，用于减少前景对原初B模式的偏倚，通过去投影和似然边际化提升r的估计精度。
In this paper we estimate diffuse foreground minimized Cosmic Microwave Background (CMB) Stokes Q and U polarization maps based upon the fundamental concept of Gaussian nature of CMB and strong non-Gaussian nature of astrophysical polarized foregrounds using WMAP nine year published polarization maps. We excise regions of the sky that define position of the known point sources, regions that are strongly contaminated by either the detector noise or by the diffuse foregrounds or both, and then perform foreground minimizations over the surviving sky regions that constitute approximately $50\%$ of…
CMBFSCNN: Cosmic Microwave Background Polarization Foreground Subtraction with Convolutional Neural Network
本研究拓展CMBFSCNN机器学习方法，纳入CMB透镜效应，结合半分图互相关技术降噪，在CMB-S4、LiteBIRD模拟数据中精确恢复CMB极化功率谱，并讨论方法对前景模型的依赖性。
Disentangling CMB $μ$ and $y$ spectral distortions from foregrounds with poorly defined spectral shapes
提出最小响应法（LRM）线性分离CMB $\mu$ 和 $y$ 谱畸变与谱形不佳的前景，优于mILC方法，并确定望远镜光学系统最佳温度。
Combining CMB datasets with consistent foreground modelling
本文通过联合分析普朗克卫星、阿塔卡马宇宙望远镜和南极望远镜的数据，构建统一的似然函数以建模CMB信号及前景，展示前景建模一致性对参数估计的重要性。
Galactic foregrounds are the main obstacle to observations of the cosmic microwave background (CMB) $B$-mode polarization. In addition to obscuring the inflationary $B$-mode signal by several orders of magnitude, Galactic foregrounds have non-trivial spectral signatures that are partially unknown and distorted by averaging effects along the line-of-sight, within the pixel/beam window, and by various analysis choices (e.g., spherical harmonic transforms and filters). Statistical moment expansion methods provide a powerful tool for modeling the effective Galactic foreground emission resulting fr…
One of the primary challenges facing upcoming CMB polarization experiments aiming to measure the inflationary B-mode signal is the removal of polarized foregrounds. The thermal dust foreground is often modeled as a single modified blackbody, however overly simplistic foreground models can bias measurements of the tensor-to-scalar ratio r. As CMB polarization experiments become increasingly sensitive, thermal dust emission models must account for greater complexity in the dust foreground while making minimal assumptions about the underlying distribution of dust properties within a beam. We use …
Future high-sensitivity measurements of the cosmic microwave background (CMB) anisotropies and energy spectrum will be limited by our understanding and modeling of foregrounds. Not only does more information need to be gathered and combined, but also novel approaches for the modeling of foregrounds, commensurate with the vast improvements in sensitivity, have to be explored. Here, we study the inevitable effects of spatial averaging on the spectral shapes of typical foreground components, introducing a moment approach, which naturally extends the list of foreground parameters that have to be d…
We study a strategy to determine miscalibrated polarization angles of cosmic microwave background (CMB) experiments using the observed $EB$ polarization power spectra of CMB and Galactic foreground emission. We apply the methodology of Minami et al.(2019) developed for full-sky observations to ground-based experiments such as Simons Observatory. We take into account the $E$-to-$B$ leakage and $\ell$-to-$\ell$ covariance due to partial sky coverage using the public code NaMaster. We show that our method yields an unbiased estimate of miscalibrated angles. Our method also enables simultaneous de…
Optimization of foreground moment deprojection for semi-blind CMB polarization reconstruction
本文提出优化的cMILC（ocMILC）流程，通过数据诊断自适应选择需反投影的前景矩数量、枢轴参数和系数，在PICO模拟中实现比NILC和cMILC更低的前景污染，并获得无偏的张标比后验。
CMB Power Spectrum Likelihood with ILC
我们扩展了ILC方法在调和空间中，包括在其CMB估计的误差。这允许参数估计例程考虑前景的影响以及与ILC方法结合的减法中的误差。我们的方法需要使用一个前景模型，我们在这里不开发。前景水平的降低使得该方法对前景模型中未考虑的误差不太敏感。模拟用于验证在生成该似然函数中使用的计算和近似。
Does the Correlation between 2MRS Galaxies and the CMB Indicate an Unmodeled CMB Foreground?
本文重新检验了基于2MRS星系与CMB温度图相关性的新CMB前景信号声称，通过模拟CMB图交叉相关分析发现原始探测样本的相关性仅在1.7σ水平或更低，证据不具说服力。
Reconstructed maps of the lensing convergence of the cosmic microwave background (CMB) will play a major role in precision cosmology in coming years. CMB lensing maps will enable calibration of the masses of high-redshift galaxy clusters and will yield precise measurements of the growth of cosmic structure through cross-correlations with galaxy surveys. During the next decade, CMB lensing reconstruction will rely heavily on temperature data, rather than polarization, thus necessitating a detailed understanding of biases due to extragalactic foregrounds. In the near term, the most significant b…
We extend the internal template foreground removal method by accounting for spatially varying spectral parameters such as the spectral indices of synchrotron and dust emission and the dust temperature. As the previous algorithm had to assume that the spectral parameters are uniform over the full sky (or some significant fraction of the sky), it resulted in a bias in the tensor-to-scalar ratio parameter $r$ estimated from foreground-cleaned polarization maps of the cosmic microwave background (CMB). The new algorithm, "Delta-map method", accounts for spatially varying spectra to first order in …
Forecasting the performance of the Minimally Informed foreground cleaning method for CMB polarization observations
本文为CMB偏振观测中的最小信息前景清理方法建立了半解析性能预测框架，并通过与直接采样和MICMAC对比验证其有效性，同时证明了数据驱动偏差校正程序的稳健性。
Quantifying Bias due to non-Gaussian Foregrounds in an Optimal Reconstruction of CMB Lensing and Temperature Power Spectra
本文利用MUSE贝叶斯推断和Agora多频模拟，评估非高斯河外前景对CMB透镜势与温度功率谱最优重建的偏差影响。
Cosmic baryon evolution during the Cosmic Dawn and Reionization results in redshifted 21-cm spectral distortions in the cosmic microwave background (CMB). These encode information about the nature and timing of first sources over redshifts 30-6 and appear at meter wavelengths as a tiny CMB distortion along with the Galactic and extragalactic radio sky, which is orders of magnitude brighter. Therefore, detection requires precise methods to model foregrounds. We present a method of foreground fitting using maximally smooth (MS) functions. We demonstrate the usefulness of MS functions over tradit…
Extragalactic foregrounds in temperature maps of the Cosmic Microwave Background (CMB) severely limit the ability of standard estimators to reconstruct the weak lensing potential. These foregrounds are not fully removable by multi-frequency cleaning or masking and can lead to large biases if not properly accounted for. For foregrounds made of a number of unclustered point sources, an estimator for the source amplitude can be derived and deprojected, removing any bias to the lensing reconstruction. We show with simulations that all of the extragalactic foregrounds in temperature can be approxim…
Cleaning Galactic foregrounds with spatially varying spectral dependence from CMB observations with \texttt{fgbuster}
本研究在下一代 CMB 偏振实验背景下，利用 \ exttt{fgbuster} 探讨了在不同像素子集中拟合银河系前景光谱参数的影响，表明允许光谱参数空间变化对于在控制前景残差的同时实现高信噪比至关重要。
Implications of scattering for CMB foreground emission modelling
本研究评估了银河系前景发射中汤姆逊散射和瑞利散射的二阶效应，发现其对总发射修正很小，但汤姆逊散射产生的B模信号接近未来CMB望远镜灵敏度，需更精确评估。
Impact of Galactic non-Gaussian foregrounds on CMB lensing measurements
本研究量化银河系尘埃前景对CMB引力透镜测量的污染，发现其对阿塔卡马宇宙学望远镜无显著影响，但西蒙斯天文台部分模型偏差超阈值，需进一步研究尘埃偏差表征与缓解方法。
Galactic foregrounds and CMB polarization
CMB偏振有望揭开测量暴胀发出的引力波背景的曙光。然而，CMB信号很微弱，很容易被银河系的前景辐射污染，因此准确测量CMB是成功观测的关键。我们回顾了宇宙微波背景辐射的偏振特性和银河系同步辐射的现有知识。然后，我们专注于S波段偏振全天巡天（S-PASS），这是最近完成的一项对整个南部天空的巡天，旨在调查银河系CMB前景。
We report an improved technique for diffuse foreground minimization from Cosmic Microwave Background (CMB) maps using a new multi-phase iterative internal-linear-combination (ILC) approach in harmonic space. The new procedure consists of two phases. In phase 1, a diffuse foreground cleaned map is obtained by performing a usual ILC operation in the harmonic space in a single iteration over the desired portion of the sky. In phase 2, we obtain the final foreground cleaned map using an iterative ILC approach also in the harmonic space, however, now, during each iteration of foreground minimizatio…
Extragalactic foregrounds are known to constitute a limiting systematic in temperature-based CMB lensing with AdvACT, SPT-3G, Simons Observatory and CMB S4. Furthermore, since these foregrounds are emitted at cosmological distances, they are also themselves lensed. The correlation between this foreground lensing and CMB lensing causes an additional bias in CMB lensing estimators. In this paper, we quantify for the first time this "lensed foreground bias" for the standard CMB lensing quadratic estimator, the CMB shear and the CMB magnification estimators, in the case of Simons Observatory and i…
The Cosmic Microwave Background anisotropies are difficult to measure at large angular scales. In this paper, we present a new analysis of the \Planck\ High Frequency Instrument data that brings the cosmological part and its major foreground signal close to the detector noise. The solar dipole signal, induced by the motion of the solar system with respect to the CMB, is a very efficient tool to calibrate a detector or a set of detectors with high accuracy. In this work, the solar dipole signal is used to extract corrections of the frequency maps offsets reducing significantly uncertainties. Th…
We present an analysis of errors on the tensor-to-scalar ratio due to residual diffuse foregrounds. We use simulated observations of a CMB polarization satellite, the Cosmic Origins Explorer, using the specifications of the version proposed to ESA in 2010 (COrE). We construct a full pipeline from microwave sky maps to $r$ likelihood, using two models of diffuse Galactic foregrounds with different complexity, and assuming component separation with varying degrees of accuracy. Our pipeline uses a linear mixture (Generalized Least Squares) solution for component separation, and a hybrid approach …
Astrophysical foregrounds and primordial tensor-to-scalar ratio constraints from CMB B-mode polarization observations
我们研究了天体物理前景对CMB B模偏振实验约束原始张量标量比r的能力的影响。为了清理前景贡献，我们使用参数，极大似然分量分离技术，并考虑优化实验设置，以在恢复的CMB图中呈现最小水平的前景残差。我们考虑几乎全天空的观测，包括两个扩散的前景组件，灰尘和同步加速器，和研究的情况下，有和没有校准误差，空间变异的前景属性，和部分或全部B模式透镜信号去除。在所有这些情况下，我们发现，在非常低的噪声水平的限制，并在没有内部或建模系统的影响，前景残差不会导致对r的最低可检测值的限制。但是，控制前景残差的需要将在确定允许r < 0.1的鲁棒检测所需的最小噪声水平方面发挥重要作用，因此在优化和预测未来任务的性能方面发挥重要作用。对于当前和拟议的实验噪声水平，发现前景残差不可忽略，并且可能会影响我们对r设置约束的能力。我们还展示了如何通过将后组件分离处理限制到较小的天空区域来显着改善约束。这种程序适用于COrE类卫星任务的情况下，可能会导致超过一个数量级的改进的可探测值r。有足够的知识的实验带通以及前景成分的比例定律，我们的结论被认为是独立的假设的整体归一化的前景，只有定量地依赖于特定的参数化假设的前景成分。
Foreground removal from WMAP 7yr polarization maps using an MLP neural network
从毫米波/亚毫米波观测中提取宇宙微波背景信号（CMB）的一个基本问题是来自银河系的辐射污染：同步辐射、自由-自由辐射和热尘埃辐射。为了从CMB信号中提取基本宇宙学参数，必须使这种污染最小化，因为它会在CMB功率谱中产生系统误差。在以前的调查中，已经证明，神经网络方法提供高质量的CMB地图从温度数据。这里的分析扩展到偏振图。作为一个具体的例子，WMAP的7年偏振数据，最可靠的测定CMB的偏振特性，进行了分析。分析采用了WMAP团队提供的频率图、噪声模型、窗函数和前景模型，不包括辅助数据。在此框架内，它表明，该网络可以提取CMB极化信号没有污染的迹象，由极化前景。与WMAP团队推导的误差相比，推导的偏振功率谱的误差得到了改善。
A needlet ILC analysis of WMAP 7-year data: estimation of CMB temperature map and power spectrum
对WMAP的7年温度图进行了重新分析，提取了减少天体物理前景和噪声污染的CMB图和CMB功率谱。所使用的方法是基于WMAP数据和前景模板的线性组合，实现对针状框架上的观察的分解。我们得到了一个干净的CMB地图与低污染的前景和噪音，以及一个新的估计的CMB温度功率谱。后者基本上与WMAP合作发布的功率谱兼容，尽管在大尺度上它稍微但系统地较低。这一差异的确切来源尚不清楚。
Modeling Extragalactic Foregrounds and Secondaries for Unbiased Estimation of Cosmological Parameters From Primary CMB Anisotropy
利用最新的物理模型和约束的最新数据，我们开发了一个唯象参数化模型的贡献强度和偏振映射在毫米波长的外部星系和Sunyaev-Zeldovich效应。我们发现这样的建模是必要的宇宙学参数从普朗克数据的估计。例如，忽略红外背景的聚类将导致7 σ的n_s偏差。我们表明，在一个完整的前景模型的同时边缘化可以消除这种偏见，同时增加宇宙学参数的统计不确定性不到20%。通过纳入更高分辨率的地面数据，可以大大减少不确定性的小幅增加。我们采用的多频分析涉及对46个总功率谱进行建模，并对17个前景参数进行边缘化。我们表明，我们也可以减少数据的CMB功率谱的最佳估计，只有两个主成分（与约束幅度）描述残留的前景污染。
Next-generation CMB satellite concepts (LiteBIRD, CORE, PIXIE, PICO) are being proposed to detect the primordial CMB B-mode polarization at large angular scales in the sky for tensor-to-scalar ratio values of ${r \lesssim 10^{-3}}$. Yet undetected, primordial CMB B-modes will provide the unique signature of the primordial gravitational waves of quantum origin predicted by inflation. We present recent forecasts on the detection of the primordial CMB B-modes in the presence of astrophysical foregrounds and gravitational lensing effects, in the context of the proposed CMB space mission CORE. We a…
Least response method to separate CMB spectral distortions from foregrounds
提出最小响应法（LRM）用于CMB谱畸变提取，该方法在保持信号恒定响应的同时最小化对前景和噪声的响应，优于传统内部线性组合法，并可通过迭代分离前景提升精度。
Extragalactic Foreground Contamination in Temperature-based CMB Lens Reconstruction
我们讨论了未解决的点源污染的影响，估计的CMB透镜潜力，从组件，如热Sunyaev-Zel'dovich效应，无线电点源，和宇宙红外背景。我们分类可能的三谱与这样的源人口，并构建估计的幅度和尺度依赖的几个主要的三谱。我们展示了如何传播这些源trispectrum的分析模型的偏见透镜。我们还构建了一个“源硬化”的透镜估计的经验显着较小的偏差时，暴露于未解决的点源比标准的二次透镜估计。我们证明了这些想法在实践中使用的天空模拟Sehgal等。例如，用于模拟ACT、SPT和Planck的宇宙方差有限实验。
We use the binned bispectrum estimator to determine the bispectra of the dust, free-free, synchrotron, and AME galactic foregrounds using maps produced by the Commander component separation method from Planck 2015 data. We find that all of these peak in the squeezed configuration, allowing for potential confusion with in particular the local primordial shape. Applying an additional functionality implemented in the binned bispectrum estimator code, we then use these galactic bispectra as templates in an $f_\mathrm{NL}$ analysis of other maps. After testing and validating the method and code wit…
Measuring the tensor to scalar ratio from CMB B-modes in presence of foregrounds
Abreg：我们研究了偏振前景发射对未来CMB实验测量张量标量比r的性能的影响。我们设计了一个组件分离管道，基于Smica方法，旨在从数据中估计r和前景污染，而无需事先假设前景的频率依赖性或空间分布。我们推导出误差条，该误差条考虑了前景贡献的不确定性。我们使用目前的知识，银河系和银河系外的前景实施的普朗克天空模型（PSM），建立模拟的天空排放的各种实验设置。我们的方法，使我们能够检测到r = 0.1，在3西格玛以上的B模式仅与普朗克数据，和r = 0.001，在6西格玛的最雄心勃勃的设计，未来的EPIC探针。我们发现，全天实验允许适当的测量的再电离凸点，尽管大规模的前景排放和污染几乎不敏感的点源和透镜，如果他们的统计贡献可以准确地建模。通过对天空中一个小而干净的部分的观测进行调查，我们发现，当测量r < 0.1时，漫射前景仍然是一个敏感的地面实验所关注的问题，其频率覆盖范围有限，但通过深场空间任务可以有效地处理，这反过来对透镜效应非常敏感。我们的结果并不显着依赖于扩散前景模型的整体水平和频率依赖性。
Framework for performance forecasting and optimization of CMB B-mode observations in presence of astrophysical foregrounds
提出了一种用于未来宇宙微波背景（CMB）实验性能预测和优化的形式化方法。我们实现它的背景下，几乎全天空，多频，B模式偏振观测，将统计不确定性，由于CMB天空统计，仪器噪声，以及前景信号的存在。我们使用参数极大似然技术和优化仪器配置与预定义的或任意的观测频率通道，约束探测器的总数或焦平面面积的减法模型的影响。我们展示了拟议的形式主义，将其应用到两种情况下的实验设置的基础上的CMBpol和COrE任务的概念，作为专用的B-模式实验。我们发现，如果在优化时可用的前景模型足够精确，则该过程可以帮助将实验的潜在科学结果提高几倍，同时允许避免过度的硬件复杂性，或者简化仪器设计而不影响其科学目标。然而，我们的分析也表明，即使可用的前景模型被认为是不够可靠的，所提出的程序可以指导设计更强大的实验设置。虽然这些设置更适合于应对比模型所预见的前景更复杂的前景，但如果模型被发现是正确的，这些设置可以确保科学结果接近最佳可实现的结果。
[Abridged] Recent results from the BICEP, Keck Array and Planck Collaborations demonstrate that Galactic foregrounds are an unavoidable obstacle in the search for evidence of inflationary gravitational waves in the cosmic microwave background (CMB) polarization. Beyond the foregrounds, the effect of lensing by intervening large-scale structure further obscures all but the strongest inflationary signals permitted by current data. With a plethora of ongoing and upcoming experiments aiming to measure these signatures, careful and self-consistent consideration of experiments' foreground- and lensi…
Enhancing Cosmological Constraints from Foreground-Cleaned CMB Maps Using Large-Scale Structure Surveys
本研究提出将星系数密度图作为ILC通道，结合CMB实验与大尺度结构巡天，可降低CMB地图的残留前景功率与方差，提升ΛCDM等宇宙学参数的约束精度，为相关实验的设计提供了预期增益依据。
Foreground removal from WMAP 5yr temperature maps using an MLP neural network
从毫米/亚毫米波段的观测中提取宇宙微波背景（CMB）信号的主要障碍之一是银河系成分（主要是同步辐射、自由辐射和热尘埃辐射）的前景污染。固有CMB信号的统计性质使得最小化CMB温度确定中的系统误差是必要的。已经证明了使用简单的神经网络从详细的模拟数据中提取CMB信号的可行性。在这里，简单的神经网络应用于WMAP 5年的温度数据，而不使用任何辅助数据。一个简单的具有两个隐藏层的\emph{multilayer perceptron}神经网络提供了超过75%的天空温度估计，其随机误差大大低于以前从这些数据中提取的随机误差。此外，系统误差，即与银河前景相关的误差非常小。这些结果为神经网络方法处理欧空局普朗克测量卫星的高质量CMB数据做好了准备。
Foreground Removal in Ground-Based CMB Observations Using a Transformer Model
本研究提出基于Transformer的TCMB模型，用于去除地基CMB观测中的前景污染，能直接处理HEALPix球面图，重建偏振图并恢复功率谱，优于CNN方法。
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