78 research outputs found
Dark Matter and Dark Energy from a single scalar field and CMB data
Axions are likely to be the Dark Matter (DM) that cosmological data require.
They arise in the Peccei Quinn solution of the strong CP problem. In a previous
work we showed that their model has a simple and natural generalization which
yields also Dark Energy (DE), in fair proportions, without tuning any
parameter: DM and DE arise from a single scalar field and are weakly coupled in
the present era. In this paper we extend the analysis of this dual-axion
cosmology and fit it to WMAP data, by using a Markov chain technique. We find
that LCDM, dynamical DE with a SUGRA potential, DE with a SUGRA potential and a
constant DE-DM coupling, as well as the dual-axion model with a SUGRA
potential, fit data with a similar accuracy. The best-fit parameters are
however fairly different, although consistency is mostly recovered at the
2-sigma level. A peculiarity of the dual-axion model with SUGRA potential is to
cause more stringent constraints on most parameters and to favor high values of
the Hubble parameter.Comment: 34 pages, 15 figures, replaced with accepted versio
Analysis of WMAP 7-year Temperature Data: Astrophysics of the Galactic Haze
We analyse WMAP 7-year temperature data, jointly modeling the cosmic
microwave background (CMB) and Galactic foreground emission. We use the
Commander code based on Gibbs sampling. Thus, from the WMAP7 data, we derive
simultaneously the CMB and Galactic components on scales larger than 1deg with
sensitivity improved relative to previous work. We conduct a detailed study of
the low-frequency foreground with particular focus on the "microwave haze"
emission around the Galactic center. We demonstrate improved performance in
quantifying the diffuse galactic emission when Haslam 408MHz data are included
together with WMAP7, and the spinning and thermal dust emission is modeled
jointly. We also address the question of whether the hypothetical galactic haze
can be explained by a spatial variation of the synchrotron spectral index. The
excess of emission around the Galactic center appears stable with respect to
variations of the foreground model that we study. Our results demonstrate that
the new galactic foreground component - the microwave haze - is indeed present.Comment: 16 pages, 16 figures, Published on Ap
DARK MATTER-DARK ENERGY COUPLING BIASING PARAMETER ESTIMATES FROM COSMIC MICROWAVE BACKGROUND DATA
The Five-To-Six-Coordination Transition of Ferric Human Serum Heme-Albumin Is Allosterically-Modulated by Ibuprofen and Warfarin: A Combined XAS and MD Study
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