Characterizing line-of-sight variability of polarized dust emission with future CMB experiments
Characterizing line-of-sight variability of polarized dust emission with future CMB experiments
复制标题
通过未来 CMB 实验表征偏振灰尘发射的视线变化
DOI：
10.1093/mnras/stac3754
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发表时间：
2023
影响因子：
4.8
通讯作者：
McBride L
中科院分区：
文献类型：
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作者：
McBride L
虽然在宇宙微波背景(CMB)分析中通常通过在每个像素中拟合一个双参数修正的黑体(MBB)模型来解释银河系尘埃发射，但通常在每个视线和每个角度像素内都发现了一些这样的云，导致它们的光谱叠加。我们通过将每个像素中的光谱能量分布(SED)建模为尘埃云属性的各种物理激励统计分布上的单个MBB光谱的积分，来研究这种叠加对基于像素的前景适配策略的影响。我们表明，用双参数MBB模型拟合这些SED通常会导致对每个像素的CMB Stokes Q和U幅度的无偏估计，除非尘埃SED和偏振角在视线上都有显著变化，在这种情况下，在说明性模型中观察到显著的(>；10σ)偏差。我们发现，当尘埃温度Td和光谱指数βd的最佳拟合值与相应的统计分布的平均值/中位数有很大偏差时，这表明如果不仔细解释，MBB模型拟合会给出尘埃在微波波段的物理性质的不具代表性的图像。利用FISHER矩阵分析，我们确定了通过拟合概率MBB模型来恢复Td和β分布参数所需的实验灵敏度，发现只有广泛分布的参数才能在单一视线上通过SED拟合来测量。
While Galactic dust emission is often accounted for in cosmic microwave background (CMB) analyses by fitting a two-parameter modified blackbody (MBB) model in each pixel, typically a number of such clouds are found along each line of sight and within each angular pixel, resulting in a superposition of their spectra. We study the effects of this superposition on pixel-based foreground fitting strategies by modeling the spectral energy distribution (SED) in each pixel as the integral of individual MBB spectra over various physically motivated statistical distributions of dust cloud properties. We show that fitting these SEDs with the two-parameter MBB model generally results in unbiased estimates of the CMB Stokes Q and U amplitudes per pixel, unless there are significant changes in both the dust SED and polarization angle along the line of sight, in which case significant (>10σ) biases are observed in an illustrative model. We find that the best-fitting values of the dust temperature,Td, and spectral index, βd, are significantly biased from the mean/median of the corresponding statistical distributions when the distributions are broad, suggesting that MBB model fits can give an unrepresentative picture of the physical properties of dust at microwave wavelengths if not interpreted carefully. Using Fisher matrix analysis, we determine the experimental sensitivity required to recover the parameters of theTdand βddistributions by fitting a probabilistic MBB model, finding that only the parameters of broad distributions can be measured by SED fitting on a single line of sight.