The present universe is dominated by repulsive dark energy. It is natural that the coupling between the dark energy and the attractive gravity has to be taken into account in studying the evolution of our universe. Here, we induce an evolution equation for dark energy–dark mattercoupled universe. The solutions of the dynamic equation provide a specific picture of cosmic evolution, which is well compatible with current observed evolution histories of both Hubble parameter and equation of state parameter of dark energy. In this picture, the already observed universe has undergone through three epochs—the epoch of equilibrium between gravity and dark energy at cosmological redshifts z [ 1, the phase transition epoch at z between about 0.5 and 1, and the present acceleration epoch starting from z ' 0:5. The expected matter-dominated deceleration epoch has not been seen yet, which requires future deep observations to look back upon more early universe.
In cosmic microwave background (CMB) experiments, foreground-cleaned temperature maps are still contaminated by the residual dipole due to uncertainties of the Doppler dipole direction and microwave radiometer sidelobe. To obtain reliable CMB maps, such contamination has to be carefully removed from observed data. We have previously built a software package for map-making, residual dipole-contamination removal, and power spectrum estimation from the Wilkinson Microwave Anisotropy Probe (WMAP) raw data. This software has now been significantly improved. With the improved software, we obtain a negative result of CMB quadrupole detection with the WMAP raw data, which is 3.2±3.5 K2 from the seven-year WMAP (WMAP7) data. This result is evidently incompatible with ～1000 K2 expected from the standard cosmological model ΛCDM. The completely missing of CMB quadrupole poses a serious challenge to the standard model and sets a strong constraint on possible models of cosmology. Due to the importance of this result for understanding the origin and early evolution of our universe, the software codes we used are opened for public checking.
We have discovered in our previous work that different observational systematics,e.g.errors from antenna pointing directions or an asynchronism between the attitude and science data may generate a pseudo-dipole signal in the full-sky maps of the cosmic microwave background (CMB) anisotropy that have been published by the Wilkinson Microwave Anisotropy Probe (WMAP) team.We have found that the antenna sidelobe response to the Doppler signal produces a similar effect.In this work,independent from the sources,we have uniformly modeled the pseudo-dipole signal and have removed it from the published WMAP7 CMB maps by model fitting.The result demonstrates that the released WMAP CMB quadrupole is almost completely artificial.
