Galactic cold dark matter as a Bose-Einstein condensate of WISPs

We propose here the dark matter content of galaxies as a cold bosonic fluid composed of Weakly Interacting Slim Particles (WISPs), represented by spin-0 axion-like particles and spin-1 hidden bosons, thermalized in the Bose-Einstein condensation state and bounded by their self-gravitational potential. We analyze two zero-momentum configurations: the polar phases in which spin alignment of two neighbouring particles is anti-parallel and the ferromagnetic phases in which every particle spin is aligned in the same direction. Using the mean field approximation we derive the Gross-Pitaevskii equations for both cases, and, supposing the dark matter to be a polytropic fluid, we describe the particles density profile as Thomas-Fermi distributions characterized by the halo radii and in terms of the scattering lengths and mass of each particle. By comparing this model with data obtained from 42 spiral galaxies and 19 Low Surface Brightness (LSB) galaxies, we constrain the dark matter particle mass to the range $10^{-6}-10^{-4} eV$ and we find the lower bound for the scattering length to be of the order $10^{-14} fm$.Comment: 13 pages; 6 figures; references added; v.3: typo corrected in the abstract, published in JCA

Avaliação da atividade fenilalanina amônia liásica em folhas de bananeira inoculadas com o fungo Mycosphaerella fijiensis.

O objetivo deste trabalho foi avaliar os atributos bioquímicos envolvidos na defesa da bananeira ao ataque do fungo M. fijiensis, notadamente avaliar o papel da enzima fenilalanina amônia liase nesta resposta, nas variedades Caprichosa, Garantida, FHIA-18, Prata Ken, Prata Anã, Maçã e Grande Naine, nos tempos: 0, 6h, 24h, 48h, 72h dias após a inoculação. Após a coleta, as folhas foram pesadas e obtidos os extratos totais por meio de maceração das folhas com tampão acetato de sódio 50 mM, pH 5,2, os quais foram utilizados nas determinações de proteínas e atividade enzimática

Some exact solutions of F(R) gravity with charged (a)dS black hole interpretation

In this paper we obtain topological static solutions of some kind of pure $F(R)$ gravity. The present solutions are two kind: first type is uncharged solution which corresponds with the topological (a)dS Schwarzschild solution and second type has electric charge and is equivalent to the Einstein-$\Lambda$-conformally invariant Maxwell solution. In other word, starting from pure gravity leads to (charged) Einstein-$\Lambda$ solutions which we interpreted them as (charged) (a)dS black hole solutions of pure $F(R)$ gravity. Calculating the Ricci and Kreschmann scalars show that there is a curvature singularity at $r=0$. We should note that the Kreschmann scalar of charged solutions goes to infinity as $r \rightarrow 0$, but with a rate slower than that of uncharged solutions.Comment: 21 pages, 4 figures, generalization to higher dimensions, references adde

Observational constraints in scalar tensor theory with tachyonic potential

We study the dynamics of the scalar tensor cosmological model in the presence of tachyon field. In an alternative approach, in two exponential and power law form of the scalar field functions in the model, field equations are solved by simultaneously best fitting the model parameters with the most recent observational data. This approach gives us an observationally verified interpretation of the dynamics of the universe. We then discuss the best fitted of equation of state parameter, the statefinder parameters and the reconstructed scalar field in the model.Comment: 16 pages, 19 figures, Will be published in JCA

Stability analysis and Observational Measurement in Chameleonic Generalised Brans--Dicke Cosmology

We investigate the dynamics of the chameleonic Generalised Brans--Dicke model in flat FRW cosmology. In a new approach, a framework to study stability and attractor solutions in the phase space is developed for the model by simultaneously best fitting the stability and model parameters with the observational data. The results show that for an accelerating universe the phantom crossing does not occur in the past and near future.Comment: 15 pages, 18 figure