121046181
Cosmological Constraints from the SDSS maxBCG Cluster Catalog
We use the abundance and weak lensing mass measurements of the SDSS maxBCG cluster catalog to simultaneously constrain cosmology and the richness-mass relation of the clusters. Assuming a flat {Lambda}CDM cosmology, we find {sigma}{sub 8}({Omega}{sub m}/0.25){sup 0.41} = 0.832 {+-} 0.033 after marginalization over all systematics. In common with previous studies, our error budget is dominated by systematic uncertainties, the primary two being the absolute mass scale of the weak lensing masses of the maxBCG clusters, and uncertainty in the scatter of the richness-mass relation. Our constraints are fully consistent with the WMAP five-year data, and in a joint analysis we find {sigma}{sub 8} = 0.807 {+-} 0.020 and {Omega}{sub m} = 0.265 {+-} 0.016, an improvement of nearly a factor of two relative to WMAP5 alone. Our results are also in excellent agreement with and comparable in precision to the latest cosmological constraints from X-ray cluster abundances. The remarkable consistency among these results demonstrates that cluster abundance constraints are not only tight but also robust, and highlight the power of optically-selected cluster samples to produce precision constraints on cosmological parameters.
198140971
Charged D stars
We describe charged soliton stars with a solid angular deficit (charged boson D stars), and find the approximate solution in the external space. Besides, we discuss the stability of charged D stars and find when the number of bosons is less than certain value, charged D stars are quantum mechanically stable.
121863790
A New Exactly Solvable Inflation Model and Its Power Spectrum
We present a new exactly solvable inflation model in which inflation can stop automatically, and in the approximately de Sitter limit, we give its power spectrum which can be tested in the future observations of cosmic microwave background anisotropy.
199673346
Generalized quartessence cosmic dynamics: phantom or quintessence with de Sitter attractor
119458029
O(N) Quintessence with a Cosine-Type Potential
We propose a quintessence model with a cosine-type potential, in which the scalar field Φa possesses an O(N) internal symmetry. The most prominent feature of this model is that it will not reduce to a cosmological constant even when |Φa| is spatially uniform and time-independent. Since different values of the potential parameter will lead to different cosmic microwave background anisotropies, which may be detectable in future satellite experiments, one can decide by observations whether the cosine-type quintessence consists of one scalar field or many fields with a symmetry constraint.
7857108
Cosmological dynamics of scalar fields with O(N) symmetry
In this paper, we study the cosmological dynamics of scalar fields with O(N) symmetry in general potentials. We compare the phase space of the dynamical systems of the quintessence and phantom and give the conditions for the existence of various attractors as well as their cosmological implications. We also show that the existence of a tracking attractor in O(N) phantom models requires the potential with Γ < 1/2, which makes the model with exponential potential possess no tracking attractor.
16218923
Evolution of relativistic jets from XTE J1550‐564 and the environment of microquasars
Two relativistic X‐ray jets have been detected with the Chandra X‐ray observatory in the black hole X‐ray transient XTE J1550‐564. We report a full analysis of the evolution of the two jets with a gamma‐ray burst external shock model. A plausible scenario suggests a cavity outside the central source and the jets first travelled with constant velocity and then are slowed down by the interactions between the jets and the interstellar medium (ISM). The best fitted radius of the cavity is ∼0.36 pc on the eastern side and ∼0.46 pc on the western side, and the densities also show asymmetry, of ∼0.015 cm−3 on the east to ∼0.21 cm−3 on the west. Large scale low density region is also found in another microquasar system, H 1743‐322. These results are consistent with previous suggestions that the environment of microquasars should be rather vacuous, compared to the normal Galactic environment. A generic scenario for microquasar jets is proposed, classifying the observed jets into three main categories, with differe...