帕克斯银河子午线巡天（PGMS）：观测和CMB偏振前景分析
The Parkes Galactic Meridian Survey (PGMS): observations and CMB polarization foreground analysis
摘要：
我们目前的意见和CMB前景分析的帕克斯银河子午线调查（PGMS），调查的银河纬度行为的偏振同步辐射在2.3 GHz的帕克斯射电望远镜。巡天由一条5度宽的带组成，它沿着银河子午线l=254度，从银河平面延伸到银河南极。我们确定了三个区域区分偏振发射特性：光盘，晕，和过渡区连接它们。晕区位于纬度|b| > 40度，在大尺度上有微弱而平滑的偏振辐射，具有中斜率$β_{\rm med} \sim -2.6$的陡峭角功率谱。圆盘区域覆盖了|b| <20度的纬度，并具有更明亮、更复杂的发射，主要是小尺度的中位斜率$β_{\rm med} = -1.8$更平坦的光谱。过渡区有陡峭的光谱，在晕，但发射增加对银河系平面从晕到盘的水平。$b \sim -20\degr$的斜率和发射结构的变化是突然的，表明一个尖锐的盘晕转变。整个光晕部分只是一个延伸超过50度的环境，具有非常低的发射，一旦缩放到70 GHz，就相当于张量与标量扰动功率比r_halo = 3.3 +/- 0.4 x 10^{-3}的CMB B模式发射。应用保守的清洗程序，我们估计了$δr \sim 2\times 10^{-3}$在70 GHz（3-sigma C.L.）假设尘埃极化率<12%，则在150 GHz处有$δr \sim 1\times 10^{-2}$。150千兆赫的限制符合计划中的亚轨道实验的目标，因此可以在这一高频率下进行实验。70 GHz的限制接近拟议的下一代空间任务的目标，因此可能不严格要求天基平台。
英文摘要：
We present observations and CMB foreground analysis of the Parkes Galactic Meridian Survey (PGMS), an investigation of the Galactic latitude behaviour of the polarized synchrotron emission at 2.3 GHz with the Parkes Radio Telescope. The survey consists of a 5-deg wide strip along the Galactic meridian l=254-deg extending from Galactic plane to South Galactic pole. We identify three zones distinguished by polarized emission properties: the disc, the halo, and a transition region connecting them. The halo section lies at latitudes |b| > 40-deg and has weak and smooth polarized emission mostly at large scale with steep angular power spectra of median slope $β_{\rm med} \sim -2.6$. The disc region covers the latitudes |b|<20-deg and has a brighter, more complex emission dominated by the small scales with flatter spectra of median slope $β_{\rm med} = -1.8$. The transition region has steep spectra as in the halo, but the emission increases toward the Galactic plane from halo to disc levels. The change of slope and emission structure at $b \sim -20\degr$ is sudden, indicating a sharp disc-halo transition. The whole halo section is just one environment extended over 50-deg with very low emission which, once scaled to 70GHz, is equivalent to the CMB B-Mode emission for a tensor-to-scalar perturbation power ratio r_halo = 3.3 +/- 0.4 x 10^{-3}. Applying a conservative cleaning procedure, we estimate an r detection limit of $δr \sim 2\times 10^{-3}$ at 70~GHz (3-sigma C.L.) and, assuming a dust polariztion fraction <12%, $δr \sim 1\times 10^{-2}$ at 150~GHz. The 150-GHz limit matches the goals of planned sub-orbital experiments, which can therefore be conducted at this high frequency. The 70-GHz limit is close to the goal of proposed next generation space missions, which thus might not strictly require space-based platforms.
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