On the presence of thermal Sunyaev–Zel'dovich induced signal in the first-year WMAP temperature maps     

C. Hernández-Monteagudo  J. A. Rubiño-Martín 《Monthly notices of the Royal Astronomical Society》2004,347(2):403-410

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A maximum-likelihood approach to removing radio sources from observations of the Sunyaev–Zel'dovich effect, with application to Abell 611     

William F. Grainger  Rhiju Das†  Keith Grainge  Michael E. Jones  Rüdiger Kneissl  G. G. Pooley  Richard D. E. Saunders 《Monthly notices of the Royal Astronomical Society》2002,337(4):1207-1214

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Astrophysical component separation of COBE-DMR 4-yr data with FastICA     

D. Maino  A. J. Banday  C. Baccigalupi  F. Perrotta  K. M. Górski 《Monthly notices of the Royal Astronomical Society》2003,344(2):544-552

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An improved approach to measuring H₀ using X-ray and SZ observations of galaxy clusters     

R. W. Schmidt  S. W. Allen  A. C. Fabian 《Monthly notices of the Royal Astronomical Society》2004,352(4):1413-1420

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Active microwave remote sensing for soil moisture measurement: a field evaluation using ERS‐2     

Jeffrey P. Walker  Paul R. Houser  Garry R. Willgoose 《水文研究》2004,18(11):1975-1997

Active microwave remote sensing observations of backscattering, such as C‐band vertically polarized synthetic aperture radar (SAR) observations from the second European remote sensing (ERS‐2) satellite, have the potential to measure moisture content in a near‐surface layer of soil. However, SAR backscattering observations are highly dependent on topography, soil texture, surface roughness and soil moisture, meaning that soil moisture inversion from single frequency and polarization SAR observations is difficult. In this paper, the potential for measuring near‐surface soil moisture with the ERS‐2 satellite is explored by comparing model estimates of backscattering with ERS‐2 SAR observations. This comparison was made for two ERS‐2 overpasses coincident with near‐surface soil moisture measurements in a 6 ha catchment using 15‐cm time domain reflectometry probes on a 20 m grid. In addition, 1‐cm soil moisture data were obtained from a calibrated soil moisture model. Using state‐of‐the‐art theoretical, semi‐empirical and empirical backscattering models, it was found that using measured soil moisture and roughness data there were root mean square (RMS) errors from 3·5 to 8·5 dB and r² values from 0·00 to 0·25, depending on the backscattering model and degree of filtering. Using model soil moisture in place of measured soil moisture reduced RMS errors slightly (0·5 to 2 dB) but did not improve r² values. Likewise, using the first day of ERS‐2 backscattering and soil moisture data to solve for RMS surface roughness reduced RMS errors in backscattering for the second day to between 0·9 and 2·8 dB, but did not improve r² values. Moreover, RMS differences were as large as 3·7 dB and r² values as low as 0·53 between the various backscattering models, even when using the same data as input. These results suggest that more research is required to improve the agreement between backscattering models, and that ERS‐2 SAR data may be useful for estimating fields‐scale average soil moisture but not variations at the hillslope scale. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Closed universe and the first Doppler peak of the cosmic microwave background spectrum     

Sergio del Campo 《Monthly notices of the Royal Astronomical Society》2003,339(1):235-242

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Radio structure of the most distant radio-detected quasar at the 10-mas scale     

S. Frey  L. Mosoni  Z. Paragi  L. I. Gurvits 《Monthly notices of the Royal Astronomical Society》2003,343(1):L20-L24

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Microwave bursts from Jupiter due to K, N, P2 and S fragments     

Hari Om Vats  M. R. Deshpansde  O. P. N. Calla  N. M. Vadher  B. M. Darji  V. Sukumaran 《Earth, Moon, and Planets》1996,73(2):125-132

This article reports the observations of microwave emission from Jupiter during the impact of K, N, P2 and S fragments of the comet Shoemaker-Levy 9. The comparison of microwave bursts intensities produced by these impacts with the impact class and the size of the impactors reveals no correlation. This is in conformity with other observations at microwave frequencies and indicates that the process of burst emission is very complex. The impacts K and N produced three microwave bursts which could possibly be due to further fragmentation of these fragments. The results are discussed in the perspective of synchrotron emission from Jupiter and possible enhancements due to an increase in the radial diffusion coefficient. However, this model does not fully explain the observations.  相似文献   

Correlation between solar microwave bursts and hard X-ray flares     

Qi-jun Fu  Yu-ying Liu  Chun-sheng Li 《Chinese Astronomy and Astrophysics》1996,20(4):L25-491

We compared the microwave bursts with short timescale fine structure observed at 2.84 GHZ at Beijing Astronomical Observatory with the hard X-ry bursts (HXB) observed by the YOHKOH satellite during the period 1991 Oct–1992 Dec, and found that of the 20 microwave events, 12 had HXB counterparts. For the typical event of 1992-06-07, we analyzed the common quasi-period oscillations on the order of 10² s and calculated the parameters of the source region, together with a brief discussion.  相似文献   

Measurement of the Sunyaev–Zel'dovich increment in massive galaxy clusters     

Michael Zemcov  Mark Halpern  Colin Borys  Scott Chapman  Wayne Holland  Elena Pierpaoli  Douglas Scott 《Monthly notices of the Royal Astronomical Society》2003,346(4):1179-1188

We have detected the Sunyaev–Zel'dovich (SZ) increment at 850 μm in two galaxy clusters (Cl 0016+16 and MS 1054.4−0321) using the Submillimetre Common User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. Fits to the isothermal β model yield a central Compton y parameter of  (2.2 ± 0.7) × 10⁻⁴  and a central 850-μm flux of  Δ I ₀= 2.2 ± 0.7 mJy beam⁻¹  in Cl 0016. This can be combined with decrement measurements to infer   y = (2.38 ±^0.36_0.34) × 10⁻⁴  and   v _pec= 400±¹⁹⁰⁰₁₄₀₀ km s⁻¹  . In MS 1054 we find a peak 850-μm flux of  Δ I ₀= 2.0 ± 1.0 mJy beam⁻¹  and   y = (2.0 ± 1.0) × 10⁻⁴  . To be successful such measurements require large chop throws and non-standard data analysis techniques. In particular, the 450-μm data are used to remove atmospheric variations in the 850-μm data. An explicit annular model is fit to the SCUBA difference data in order to extract the radial profile, and separately fit to the model differences to minimize the effect of correlations induced by our scanning strategy. We have demonstrated that with sufficient care, SCUBA can be used to measure the SZ increment in massive, compact galaxy clusters.  相似文献