* Astronomy

Title: Relic Gravitational Waves And CMB Polarisation In The Accelerating Universe
Authors: Y. Zhang, W. Zhao, T. Y. Xia, X. Z. Er, H. X. Miao

In this paper we briefly present our works on the relic gravitational waves (RGW) and the CMB polarisation in the accelerating universe. The spectrum of RGW has been obtained, showing the influence of the dark energy. Compared with those from non-accelerating models, the shape of the spectrum is approximately similar, nevertheless, the amplitude of RGW now acquires a suppressing factor of the ratio of matter over dark energy \propto \Omega_m/\Omega_{\Lambda} ~ 0.4 over almost the whole range of frequencies. The RGW spectrum is then used as the source to calculate the spectra of CMB polarisation. By a two half Gaussian function as an approximation to the visibility function during the photon decoupling, both the "electric" and "magnetic" spectra have been analytically derived, which are quite close to the numerical ones. Several physical elements that affect the spectra have been examined, such as the decoupling process, the inflation, the dark energy, the baryons, etc.

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Title: Five-Year Wilkinson Microwave Anisotropy Probe (WMAP)Observations: Beam Maps and Window Functions
Authors: R. S. Hill, J. L. Weiland, N. Odegard (ADNET), E. Wollack, G. Hinshaw (NASA/GSFC), D. Larson, C. L. Bennett (JHU), M. Halpern (UBC), L. Page (Princeton), J. Dunkley (Princeton, Oxford), B. Gold (JHU), N. Jarosik (Princeton), A. Kogut (NASA/GSFC), M. Limon (Columbia), M. R. Nolta (CITA), D. N. Spergel (Princeton), G. S. Tucker (Brown), E. L. Wright (UCLA)

Cosmology and other scientific results from the WMAP mission require an accurate knowledge of the beam patterns in flight. While the degree of beam knowledge for the WMAP one-year and three-year results was unprecedented for a CMB experiment, we have significantly improved the beam determination as part of the five-year data release. Physical optics fits are done on both the A and the B sides for the first time. The cutoff scale of the fitted distortions on the primary mirror is reduced by a factor of ~2 from previous analyses. These changes enable an improvement in the hybridisation of Jupiter data with beam models, which is optimised with respect to error in the main beam solid angle. An increase in main-beam solid angle of ~1% is found for the V2 and W1-W4 differencing assemblies. Although the five-year results are statistically consistent with previous ones, the errors in the five-year beam transfer functions are reduced by a factor of ~2 as compared to the three-year analysis. We present radiometry of the planet Jupiter as a test of the beam consistency and as a calibration standard; for an individual differencing assembly, errors in the measured disk temperature are ~0.5%.

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Title: On the detection of transplanckian effects in the cosmic microwave background
Authors: Nicolaas E. Groeneboom, Oystein Elgaroy
(Version v2)

Quantum gravity effects are expected modify the primordial density fluctuations produced during inflation and leave their imprint on the cosmic microwave background observed today. We present a new analysis discussing whether these effects are detectable, considering both currently available data and simulated results from an optimal CMB experiment. We find that the WMAP data show no evidence for the particular signature considered in this work, but give an upper bound on the parameters of the model. The hypothetical experiment gives an ambivalent answer: the effects might be detectable. This fuzzy conclusion is a result of the nature of the oscillations, since they give rise to a likelihood hyper-surface riddled with local maxima. A simple Bayesian analysis shows no significant evidence for the simulated data to prefer a transplanckian model. Conventional Markov Chain Monte Carlo (MCMC) methods are not suitable for exploring this complicated landscape, but alternative methods that might work exist. We conclude by explaining why it is very unlikely that transplanckian effects can be detected convincingly by CMB data alone, even for optimistic assumptions about the energy scale of quantum gravity.

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Title: What do WMAP and SDSS really tell about inflation?
Authors: Julien Lesgourgues, Alexei A. Starobinsky, Wessel Valkenburg
(Version v2)

We derive new constraints on the Hubble function H(phi) and subsequently on the inflationary potential V(phi) from WMAP 3-year data combined with the Sloan Luminous Red Galaxy survey (SDSS-LRG), using a new methodology which appears to be more generic, conservative and model-independent than in most of the recent literature, since it depends neither on the slow-roll approximation, nor on any extrapolation scheme for the potential beyond the observable e-fold range, nor on additional assumptions about initial conditions for the inflaton velocity. This last feature represents the main improvement of this work, and is made possible by the reconstruction of H(phi) prior to V(phi). Our results only rely on the assumption that within the observable range, corresponding to ~ 10 e-folds, inflation is not interrupted and the function H(phi) is smooth enough for being Taylor-expanded at order one, two or three. We conclude that the variety of potentials allowed by the data is still large. However, it is clear that the first two slow-roll parameters are really small while the validity of the slow-roll expansion beyond them is not established.

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