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arXiv 1611.02418astro-ph.GAastro-ph.CO
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用GASS HI资料模拟和模拟南银河系帽上方大尺度极化尘埃发射

Modelling and simulation of large-scale polarized dust emission over the southern Galactic cap using the GASS HI data

Tuhin Ghosh, Francois Boulanger, Peter G. Martin, Andrea Bracco, Flavien Vansyngel, Jonathan Aumont, Jamie Bock, Olivier Doré, Urmas Haud, Peter M. W. Kalberla, Paolo Serra

摘要:

普朗克巡天量化了极化的银河前景,并确定它们是寻找宇宙暴胀期间由原始引力波引起的宇宙微波背景(CMB)B模式信号的主要限制因素。因此,准确地分离银河系前景将我们对磁化星际介质(ISM)的理解与这一探索联系在一起。从普朗克数据分析的两个最相关的经验结果是视线退极化所产生的波动的银河磁场方向和对齐的行星尘埃结构与磁场在银河系高纬度。此外,Planck和HI发射数据的结合表明,大多数的尘埃结构是在冷中性介质。本文的目的是测试这些突出的观测结果,综合起来,是否可以充分说明尘埃极化的统计特性,在选定的低柱密度区域,包括34%的南银河帽($b \le -30°$)。要做到这一点,我们构建了一个尘埃模型,采用HI柱密度图作为示踪剂的尘埃强度结构和银河系磁场的现象学描述。通过调整尘埃模型的参数,我们能够重现普朗克尘埃观测在353 GHz的选定区域。由这样的尘埃模型启用的偏振尘埃排放的现实模拟是有用的测试组件分离方法的准确性,研究非高斯性,并限制与频率的去相关量。

英文摘要:

The Planck survey has quantified polarized Galactic foregrounds and established that they are a main limiting factor in the quest for the cosmic microwave background (CMB) B-mode signal induced by primordial gravitational waves during cosmic inflation. Accurate separation of the Galactic foregrounds therefore binds this quest to our understanding of the magnetized interstellar medium (ISM). The two most relevant empirical results from analysis of Planck data are line of sight depolarization arising from fluctuations of the Galactic magnetic field orientation and alignment of filamentary dust structures with the magnetic field at high Galactic latitude. Furthermore, Planck and HI emission data in combination indicate that most of the filamentary dust structures are in the cold neutral medium. The goal of this paper is to test whether these salient observational results, taken together, can account fully for the statistical properties of the dust polarization over a selected low column density region comprising 34 % of the southern Galactic cap ($b \le -30°$). To do this, we construct a dust model that incorporates HI column density maps as tracers of the dust intensity structures and a phenomenological description of the Galactic magnetic field. By adjusting the parameters of the dust model, we were able to reproduce the Planck dust observations at 353 GHz in the selected region. Realistic simulations of the polarized dust emission enabled by such a dust model are useful for testing the accuracy of component separation methods, studying non-Gaussianity, and constraining the amount of decorrelation with frequency.

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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