期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 412, 期 2, 页码 1151-1161出版社
OXFORD UNIV PRESS
DOI: 10.1111/j.1365-2966.2010.17971.x
关键词
methods: statistical; ISM: structure; infrared: ISM
资金
- NASA
- Science and Technology Facilities Council [PP/D000963/1, ST/G002533/1, ST/I005765/1, ST/G002630/1, ST/G002622/1, ST/I001212/1] Funding Source: researchfish
- UK Space Agency [ST/G003874/1] Funding Source: researchfish
- STFC [ST/G002630/1, ST/I005765/1, ST/I001212/1, PP/D000963/1, ST/H001530/1, ST/G002622/1, ST/G002533/1] Funding Source: UKRI
We study the spectral energy distribution (SED) and the power spectrum of Galactic cirrus emission observed in the 14 deg2 Science Demonstration Phase field of the Herschel-ATLAS using Herschel and IRAS data from 100 to 500 mu m. We compare the Spectral and Photometric Imaging Receiver (SPIRE) 250, 350 and 500 mu m maps with IRAS 100-mu m emission, binned in 6-arcmin pixels. We assume a modified blackbody SED with dust emissivity parameter beta (F proportional to lambda-beta) and a single dust temperature T-d, and find that the dust temperature and emissivity index varies over the science demonstration field as and 1 < beta < 4. The latter values are somewhat higher than the range of beta often quoted in the literature (1 < beta < 2). We estimate the mean values of these parameters to be T-d = 19.0 +/- 2.4 K and beta = 1.4 +/- 0.4. In regions of bright cirrus emission, we find that the dust has similar temperatures with , and similar values of beta, ranging from 1.4 +/- 0.5 to 1.9 +/- 0.5. We show that T-d and beta associated with diffuse cirrus emission are anti-correlated and can be described by the relationship: beta(T-d) = NT alpha(d) with [N = 116 +/- 38, alpha = -1.4 +/- 0.1]. The strong correlation found in this analysis is not just limited to high-density clumps of cirrus emission as seen in previous studies, but is also seen in diffuse cirrus in low-density regions. To provide an independent measure of T-d and beta, we obtain the angular power spectrum of the cirrus emission in the IRAS and SPIRE maps, which is consistent with a power spectrum of the form P(k) = P-0(k/k(0))gamma, where gamma = 2.6 +/- 0.2 for scales of 50-200 arcmin in the SPIRE maps. The cirrus rms fluctuation amplitude at angular scales of 100 arcmin is consistent with a modified blackbody SED with and beta = 1.3 +/- 0.2, in agreement with the values obtained above.
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