Infrared-correlated 31-GHz radio emission from Orion East
Infrared-correlated 31-GHz radio emission from Orion East
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Orion East 的红外相关 31 GHz 无线电发射
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发表时间：
2010
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通讯作者：
R. Watson
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作者：
C. Dickinson;S. Casassus;R. Davies;J. Allison;R. Bustos;K. Cleary;R. Davis;M. Jones;T. Pearson;A. Readhead;R. Reeves;A. Taylor;C. Tibbs;R. Watson
林德的黑云LDN1622代表了异常尘埃发射的最好例子之一，可能起源于小的旋转尘埃颗粒。我们展示了LDN1621的宇宙背景成像仪（CBI）的31 ghz数据，LDN1621是LDN1622以北的漫射黑云，位于猎户座东部地区。在31 GHz，≈20 - 30 mJy波束−1下检测到一个直径≈20 arcmin的散射发射破碎环状结构，角分辨率为≈5 arcmin。环状结构与12 ~ 100 μm远红外（FIR）发射高度相关，相关系数r≈0.7 ~ 0.8，在~ 10σ处显著。因此，31千兆赫的fir相关发射似乎主要是由于与尘埃有关的辐射。多频数据用于限制可能产生31 ghz通量的其他发射成分。对4.85 GHz的GB6巡天图的分析得出，在CBI分辨率下，7.2 mJy波束−1（观测通量的30%）的自由-自由发射上限为3σ。因此，31千兆赫的大部分通量似乎主要是由于尘埃辐射。孔径测光，角分辨率为13角分，孔径直径为30角分，允许使用IRAS图和Wilkinson微波各向异性探测器5年w波段图，频率为93.5 GHz。一个单一的修正黑体模型被拟合到数据中，以估计热尘埃的贡献，在31 GHz时达到10%。在该模型中，在31 GHz处可以看到1.52±0.66 Jy （2.3σ）的过剩。与IRAS 100 μm的相关系数为18.1±4.4 μK (MJy sr−1)−1，与LDN1622的值一致。
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-like structure with diameter ≈20 arcmin of diffuse emission is detected at 31 GHz, at ≈20–30 mJy beam−1 with an angular resolution of ≈5 arcmin. The ring-like structure is highly correlated with far-infrared (FIR) emission at 12– 100 μm with correlation coefficients of r ≈ 0.7–0.8, significant at ∼10σ . The FIR-correlated emission at 31 GHz therefore appears to be mostly due to radiation associated with dust. Multifrequency 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 ( 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 Wilkinson Microwave Anisotropy Probe 5-yr 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 ∼10 per cent at 31 GHz. In this model, an excess of 1.52 ± 0.66 Jy (2.3σ ) is seen at 31 GHz. Correlations with the IRAS 100 μm gave a coupling coefficient of 18.1 ± 4.4 μK (MJy sr−1)−1, consistent with the values found for LDN1622.