Absorption features of high-redshift galactic winds     

A. P. M. Fangano  A. Ferrara  P. Richter † 《Monthly notices of the Royal Astronomical Society》2007,381(2):469-488

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The effect of reionization on the cosmic microwave background–density correlation     

Tommaso Giannantonio  Robert Crittenden 《Monthly notices of the Royal Astronomical Society》2007,381(2):819-826

In this paper, we show how the rescattering of cosmic microwave background photons after cosmic reionization can give a significant linear contribution to the temperature–matter cross-correlation measurements. These anisotropies, which arise via a late-time Doppler effect, are on scales much larger than the typical scale of non-linear effects at reionization; they can contribute to degree scale cross-correlations and could affect the interpretation of similar correlations resulting from the integrated Sachs–Wolfe effect. While expected to be small at low redshifts, these correlations can be large given a probe of the density at high redshift, and so could be a useful probe of the cosmic reionization history.  相似文献   

Intrinsic galaxy alignments from the 2SLAQ and SDSS surveys: luminosity and redshift scalings and implications for weak lensing surveys     

Christopher M. Hirata  Rachel Mandelbaum †  Mustapha Ishak  Uro&#; Seljak  Robert Nichol  Kevin A. Pimbblet  Nicholas P. Ross  David Wake 《Monthly notices of the Royal Astronomical Society》2007,381(3):1197-1218

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Virialization of cosmological structures in models with time-varying equation of state     

Spyros Basilakos  Nikos Voglis 《Monthly notices of the Royal Astronomical Society》2007,374(1):269-275

We study the virialization of the cosmic structures in the framework of flat cosmological models where the dark energy component plays an important role in the global dynamics of the Universe. In particular, our analysis focuses on the study of the spherical matter perturbations, as the latter decouple from the background expansion, start to 'turn around' and finally collapse. We generalize this procedure, taking into account models with an equation of state which vary with time, and provide a complete formulation of the cluster virialization attempting to address the non-linear regime of structure formation. In particular, assuming that clusters have collapsed prior to the epoch of z _f≃ 1.4, in which the most distant cluster has been found, we show that the behaviour of the spherical collapse model depends on the functional form of the equation of state.  相似文献   

A potentially pure test of cosmic geometry: galaxy clusters and the real space Alcock–Paczyński test     

Young-Rae Kim  Rupert A. C. Croft 《Monthly notices of the Royal Astronomical Society》2007,374(2):535-546

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The correlation between the distribution of galaxies and 21-cm emission at high redshifts     

J. Stuart B. Wyithe  Abraham Loeb 《Monthly notices of the Royal Astronomical Society》2007,375(3):1034-1042

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General relativistic self-similar solutions in cosmology     

Adi Nusser 《Monthly notices of the Royal Astronomical Society》2007,375(3):1106-1110

We present general relativistic solutions for self-similar spherical perturbations in an expanding cosmological background of cold pressure-less gas. We focus on solutions having shock discontinuities propagating in the surrounding cold gas. The pressure, p , and energy density, μ, in the shock-heated matter are assumed to obey   p = w μ  , where w is a positive constant. Consistent solutions are found for shocks propagating from the symmetry centre of a region of a positive density excess over the background. In these solutions, shocks exist outside the radius marking the event horizon of the black hole which would be present in a shock-less collapse. For large jumps in the energy density at the shock, a black hole is avoided altogether and the solutions are regular at the centre. The shock-heated gas does not contain any sonic points, provided the motion of the cold gas ahead of the shock deviates significantly from the Hubble flow. For shocks propagating in the uniform background, sonic points always appear for small jumps in the energy density. We also discuss self-similar solutions without shocks in fluids with   w < −1/3  .  相似文献   

Constraining the nature of dark energy using the Square Kilometer Array Telescope     

A. Torres-Rodríguez  C. M. Cress 《Monthly notices of the Royal Astronomical Society》2007,376(4):1831-1837

We investigate the potential of the Square Kilometer Array Telescope (SKA) to constrain the sound speed of dark energy. The Integrated Sachs Wolfe (ISW) effect results in a significant power spectrum signal when Cosmic Microwave Background (CMB) temperature anisotropies are cross-correlated with galaxies detectable with the SKA in H  i . We consider using this measurement, the autocorrelation of H  i galaxies and the CMB temperature power spectrum to derive constraints on the sound speed. We study the contributions to the cross-correlation signal made by galaxies at different redshifts and use redshift tomography to improve the signal-to-noise. We use a  χ²  analysis to estimate the significance of detecting a sound speed different from that expected in quintessence models, finding that there is potential to distinguish very low sound speeds from the quintessence value.  相似文献   

Genus topology of the cosmic microwave background from the WMAP 3-year data     

J. Richard Gott  III    Wesley N. Colley &#;  Chan-Gyung Park  Changbom Park  Charles Mugnolo 《Monthly notices of the Royal Astronomical Society》2007,377(4):1668-1678

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EGUP与黑洞熵的修正值     

白吉龙  温廷敦 《天文学报》2015,56(1):1-6

目前,人们对黑洞Bekenstein-Hawking熵的量子修正值产生了极大的兴趣,尤其是黑洞熵对数修正项的系数.在广义不确定关系(GUP)的基础上,通过引入了推广的广义不确定关系(EGUP),运用面积定理计算了3类时空的黑洞熵的修正值,得到的黑洞熵的修正项的系数是正的.这种计算方法不仅对单视界时空适用,而且对有内视界的黑洞时空依然成立,并且在EGUP基础上计算出黑洞熵的修正值.相比GUP基础上得到的黑洞熵,EGUP可以应用于大尺度时空下,所以应用范围更广.此计算方法简洁明了,物理意义明确,可为黑洞熵对数修正值系数的确定提供参考.  相似文献