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arXiv 1003.3815astro-ph.GAastro-ph.CO
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猎户座东红外相关31 GHz射电发射

IR-correlated 31 GHz radio emission from Orion East

C. Dickinson, S. Casassus, R. D. Davies, J. R. Allison, R. Bustos, K. Cleary, R. J. Davis, M. E. Jones, T. J. Pearson, A. C. S. Readhead, R. Reeves, A. C. Taylo… 展开作者

C. Dickinson, S. Casassus, R. D. Davies, J. R. Allison, R. Bustos, K. Cleary, R. J. Davis, M. E. Jones, T. J. Pearson, A. C. S. Readhead, R. Reeves, A. C. Taylor, C. T. Tibbs, R. A. Watson

备注：
8 pages, 3 figures, 3 tables, submitted to MNRAS
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摘要：

林德暗云LDN 1622代表了异常尘埃排放的最佳例子之一，可能源于小的旋转尘埃颗粒。我们提出了LDN 1621的宇宙背景成像仪（CBI）31 GHz数据，LDN 1622北部的一个被称为猎户座东部的地区的一个弥漫的暗云。在31 GHz、\approx 20-30 mJ光束\approx处，以\approx 5 arcmin的角分辨率检测到扩散发射的直径g为\approx 20 arcmin的断裂环。环状结构与$12-100 μ$ m处的远红外发射高度相关，相关系数r \approx为0.7-0.8，在$\sim10σ$处显著。多频数据被用来限制可能对31 GHz通量有贡献的其他发射成分。对4.85 GHz的GB 6测量图的分析得出自由-自由发射的$3σ$上限为7.2 mJ光束$^{-1}$（$\la 30 per cent of the observed flux) at the CBI resolution. The bulk of the 31 GHz flux therefore appears to be mostly due to dust radiation. Aperture photometry, at an angular resolution of 13 arcmin and with an aperture of diameter 30 arcmin, allowed the use of IRAS maps and the {\it WMAP} 5-year W-band map at 93.5 GHz. A single modified blackbody model was fitted to the data to estimate the contribution from thermal dust, which amounts to $ \sim $ 10 per cent at 31 GHz. In this model, an excess of 1.52\pm 0.66 Jy (2.3σ) is seen at 31 GHz. Future high frequency $ \sim $ 100-1000 GHz data, such as those from the {\it Planck} satellite, are required to accurately determine the thermal dust contribution at 31 GHz. Correlations with the IRAS $ 100 μ $m gave a coupling coefficient of $ 18.1 \pm 4.4 μ $K (MJy/sr)$ ^{-1}$，与LDN 1622的值一致。

英文摘要：

Lynds dark cloud LDN1622 represents one of the best examples of anomalous dust emission, possibly originating from small spinning dust grains. We present Cosmic Background Imager (CBI) 31 GHz data of LDN1621, a diffuse dark cloud to the north of LDN1622 in a region known as Orion East. A broken ring with diameter g\approx 20 arcmin of diffuse emission is detected at 31 GHz, at \approx 20-30 mJy beam$^{-1}$ with an angular resolution of \approx 5 arcmin. The ring-like structure is highly correlated with Far Infra-Red emission at $12-100 μ$m with correlation coefficients of r \approx 0.7-0.8, significant at $\sim10σ$. Multi-frequency data are used to place constraints on other components of emission that could be contributing to the 31 GHz flux. An analysis of the GB6 survey maps at 4.85 GHz yields a $3σ$ upper limit on free-free emission of 7.2 mJy beam$^{-1}$ ($\la 30 per cent of the observed flux) at the CBI resolution. The bulk of the 31 GHz flux therefore appears to be mostly due to dust radiation. Aperture photometry, at an angular resolution of 13 arcmin and with an aperture of diameter 30 arcmin, allowed the use of IRAS maps and the {\it WMAP} 5-year W-band map at 93.5 GHz. A single modified blackbody model was fitted to the data to estimate the contribution from thermal dust, which amounts to $\sim$ 10 per cent at 31 GHz. In this model, an excess of 1.52\pm 0.66 Jy (2.3σ) is seen at 31 GHz. Future high frequency $\sim$ 100-1000 GHz data, such as those from the {\it Planck} satellite, are required to accurately determine the thermal dust contribution at 31 GHz. Correlations with the IRAS $100 μ$m gave a coupling coefficient of $18.1\pm4.4 μ$K (MJy/sr)$^{-1}$, consistent with the values found for LDN1622.

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