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arXiv 0811.1040astro-ph
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用WMAP五年资料约束纺纱粉尘参数

Constraining Spinning Dust Parameters with the WMAP Five-Year Data

Gregory Dobler, Bruce T. Draine, Douglas P. Finkbeiner

摘要:

我们的特点旋转尘埃排放在温暖的电离介质中比较银河系尘埃和Halalpha的模板与威尔金森微波各向异性探测器的5年地图。α-相关的微波发射偏离电离气体预期的热韧致辐射(自由-自由)光谱,表现出额外的宽凸起峰值在~40 GHz,提供~20%的峰值强度。我们确认,该隆起与修改后的Draine & Lazarian(1998)旋转尘埃模型一致,尽管发射的峰值频率略低于先前声称的50 GHz。这种频移是由WMAP 3年数据的大尺度模态中的系统误差引起的,这些误差在5年数据发布中得到了校正。我们表明,凹凸是不是在Halpha模板中的错误的结果,通过分析区域的高自由自由强度,其中WMAP K波段地图可以被用作自由模板。我们排除了一个纯粹的自由自由光谱的α相关发射在高置信度:~ 27西格玛的几乎全天空的拟合,即使在边缘化的CMB互相关偏差。我们还通过搜索Draine & Lazarian模型的参数空间,但让振幅浮动,扩展了以前的分析。特征电偶极矩和密度的合理值的最佳拟合需要约0.3的振幅因子。这表明,在温暖的电离介质中的小的多环芳烃被耗尽的一个因素~3。

英文摘要:

We characterize spinning dust emission in the warm ionized medium by comparing templates of Galactic dust and Halpha with the 5-year maps from the Wilkinson Microwave Anisotropy Probe. The Halpha-correlated microwave emission deviates from the thermal bremsstrahlung (free-free) spectrum expected for ionized gas, exhibiting an additional broad bump peaked at ~40 GHz which provides ~20% of the peak intensity. We confirm that the bump is consistent with a modified Draine & Lazarian (1998) spinning dust model, though the peak frequency of the emission is somewhat lower than the 50 GHz previously claimed. This frequency shift results from systematic errors in the large-scale modes of the 3-year WMAP data which have been corrected in the 5-year data release. We show that the bump is not the result of errors in the Halpha template by analyzing regions of high free-free intensity, where the WMAP K-band map may be used as the free-free template. We rule out a pure free-free spectrum for the Halpha-correlated emission at high confidence: ~27sigma for the nearly full-sky fit, even after marginalizing over the CMB cross-correlation bias. We also extend the previous analysis by searching the parameter space of the Draine & Lazarian model but letting the amplitude float. The best fit for reasonable values of the characteristic electric dipole moment and density requires an amplitude factor of ~0.3. This suggests that small PAHs in the warm ionized medium are depleted by a factor of ~3.

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