Parametrization of Born-Infeld Type Phantom Dark Energy Model

Applying the parametrization of dark energy density, we can construct directly independent-model potentials. In Born-Infeld type phantom dark energy model, we consider four special parametrization equation of state parameter. The evolutive behavior of dark energy density with respect to red-shift $z$, potentials with respect to $\phi$ and $z$ are shown mathematically. Moreover, we investigate the effect of parameter $\eta$ upon the evolution of the constructed potential with respect to $z$. These results show that the evolutive behavior of constructed Born-Infeld type dark energy model is quite different from those of the other models.Comment: 5 pages, 4 figures, Accepted for publication in Astrophysics & Space Scienc

Five-Year Wilkinson Microwave Anisotropy Probe (WMAP)Observations: Beam Maps and Window Functions

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 approximately 2 from previous analyses. These changes enable an improvement in the hybridization of Jupiter data with beam models, which is optimized with respect to error in the main beam solid angle. An increase in main-beam solid angle of approximately 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 approximately 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 approximately 0.5%

Reconstruction of some cosmological models in f(R,T) gravity

In this paper, we reconstruct cosmological models in the framework of $f(R,T)$ gravity, where $R$ is the Ricci scalar and $T$ is the trace of the stress-energy tensor. We show that the dust fluid reproduces $\Lambda$CDM, phantom-non-phantom era and the phantom cosmology. Further, we reconstruct different cosmological models including, Chaplygin gas, scalar field with some specific forms of $f(R,T)$. Our numerical simulation for Hubble parameter shows good agreement with the BAO observational data for low redshifts $z<2$.Comment: 12 pages, 2 figure

Five-Year Wilkinson Microwave Anisotropy Probe (WMAP1) Observations: Galactic Foreground Emission

We present a new estimate of foreground emission in the WMAP data, using a Markov chain Monte Carlo (MCMC) method. The new technique delivers maps of each foreground component for a variety of foreground models, error estimates of the uncertainty of each foreground component, and provides an overall goodness-of-fit measurement. The resulting foreground maps are in broad agreement with those from previous techniques used both within the collaboration and by other authors. We find that for WMAP data, a simple model with power-law synchrotron, free-free, and thermal dust components fits 90% of the sky with a reduced X(sup 2) (sub v) of 1.14. However, the model does not work well inside the Galactic plane. The addition of either synchrotron steepening or a modified spinning dust model improves the fit. This component may account for up to 14% of the total flux at Ka-band (33 GHz). We find no evidence for foreground contamination of the CMB temperature map in the 85% of the sky used for cosmological analysis

Stability analysis of agegraphic dark energy in Brans-Dicke cosmology

Stability analysis of agegraphic dark energy in Brans-Dicke theory is presented in this paper. We constrain the model parameters with the observational data and thus the results become broadly consistent with those expected from experiment. Stability analysis of the model without best fitting shows that universe may begin from an unstable state passing a saddle point and finally become stable in future. However, with the best fitted model, There is no saddle intermediate state. The agegraphic dark energy in the model by itself exhibits a phantom behavior. However, contribution of cold dark matter on the effective energy density modifies the state of teh universe from phantom phase to quintessence one. The statefinder diagnosis also indicates that the universe leaves an unstable state in the past, passes the LCDM state and finally approaches the sable state in future.Comment: 15 pages, 12 figure

Modified GBIG Scenario as an Alternative for Dark Energy

We construct a DGP-inspired braneworld model where induced gravity on the brane is modified in the spirit of $f(R)$ gravity and stringy effects are taken into account by incorporation of the Gauss-Bonnet term in the bulk action. We explore cosmological dynamics of this model and we show that this scenario is a successful alternative for dark energy proposal. Interestingly, it realizes the phantom-like behavior without introduction of any phantom field on the brane and the effective equation of state parameter crosses the cosmological constant line naturally in the same way as observational data suggest.Comment: 16 pages, 6 figures, Accepted for publication in JCA

On the anomalous large-scale flows in the Universe

Recent combined analyses of the CMB and galaxy cluster data reveal unexpectedly large and anisotropic peculiar velocity fields at large scales. We study cosmic models with included vorticity, acceleration and total angular momentum of the Universe in order to understand the phenomenon. The Zeldovich model is used to mimic the low redshift evolution of the angular momentum. Solving coupled evolution equations of the second kind for density-contrast in corrected Ellis-Bruni covariant and gauge-invariant formalism one can properly normalize and evaluate integrated Sachs-Wolfe effect and peculiar velocity field. The theoretical results compared to the observations favor a much larger matter content of the Universe than that of the concordance model. Large-scale flows appear anisotropic with dominant components placed in the plane perpendicular to the axis of vorticity(rotation). The integrated Sachs-Wolfe term has negative contribution to the CMB fluctuations for the negative cosmological constant and it can explain the observed small power of the CMB TT spectrum at large scales. The rate of the expansion of the Universe can be substantially affected by the angular momentum if its magnitude is large enough.Comment: 13 pages, 6 tables, 4 figures, 36 references; version to appear in Eur. Phys. J.

Extended Theories of Gravity and their Cosmological and Astrophysical Applications

We review Extended Theories of Gravity in metric and Palatini formalism pointing out their cosmological and astrophysical application. The aim is to propose an alternative approach to solve the puzzles connected to dark components.Comment: 44 pages, 11 figure

Non-linear parallel solver for detecting point sources in CMB maps using Bayesian techniques

Abstract In this work we present a suitable computational tool to deal with large matrices and solve systems of non-linear equations. This technique is applied to a very interesting problem: the detection and flux estimation of point sources in Cos- mic Microwave Background (CMB) maps, which allows a good determination of CMB primordial fluctuations and leads to a better knowledge of the chemistry at the early stages of the Universe. The method uses previous information about the statis- tical properties of the sources, so that this knowledge is incorporated in a Bayesian scheme. Simulations show that our approach allows the detection of more sources than previous non-Bayesian techniques, with a small computation timeThis work was financially supported by the Spanish Ministerio de Ciencia e Innovacion and by FEDER Projects (TEC2012-38142-C04, TIN2010-14971, TEC2009-13741 and CAPAP-H4 TIN2011-15734-E) Universitat Politecnica de Valencia through Programa de Apoyo a la Investigacion y Desarrollo (PAID-05-11) and Generalitat Valenciana through project PROMETEO/2009/013. We thank Diego Herranz for his help with the CMB simulations.Alonso, P.; Argüeso, F.; Cortina, R.; Ranilla, J.; Vidal Maciá, AM. (2013). Non-linear parallel solver for detecting point sources in CMB maps using Bayesian techniques. Journal of Mathematical Chemistry. 51(4):1153-1163. https://doi.org/10.1007/s10910-012-0078-711531163514P. Alonso, D. Argüelles, J. Ranilla, A.M. Vidal, The solution of Block-Toeplitz linear systems of equations in multicore computers. J. Supercomput. (2012). doi: 10.1007/s11227-012-0824-4Alonso P., Argüeso F., Cortina R., Ranilla J., Vidal A.M.: Detecting point sources in CMB maps using an eficient parallel algorithm. J. Math. Chem. 50, 410–420 (2012)Argüeso F., Salerno E., Herranz D., Sanz J.L., Kuruoglu E.E., Kayabol K.: A Bayesian technique for the detection of point sources in CMB maps. Mon. Not. Roy. Astron. Soc. 414, 410–417 (2011)Carvalho P., Rocha G., Hobson M.: A fast Bayesian approach to discrete object detection in astronomical images. PowellSnakes I. Mon. Not. Roy. Astron. Soc. 393, 681 (2009)Planck Collaboration, P.A.R. Ade et al. Planck early results I. The Planck mission. Astron. Astrophys. 536, A1 (2011)De Zotti G. et al.: Predictions for high-frequency radio surveys of extragalactic sources. Astron. Astrophys. 431, 893–903 (2005)Dubrovich V.K.: Blurring of spatial microwave fluctuations by molecular last scattering. Astron. Lett. J. Astron. Space Astrophys. 19, 53 (1993)Golub G.H., Van Loan C.F.: Matrix Computations. Johns Hopkins University Press, Baltimore (1996)Herranz D., Vielva P.: Microwave backgound images. IEEE Signal Process. Mag. 27, 67–75 (2010)D. Herranz, F. Argüeso, P. Carvalho, Compact source detection in multichannel microwave surveys: from SZ clusters to polarized sources. Adv. Astron. (2012). doi: 10.1155/2012/410965Maoli R., Melchiorri F., Tosti D.: Molecules in the postrecombination universe and microwave background anisotropies. Astrophys. J. 425, 372 (1994)Nolta M.R. et al.: Five-year wilkinson microwave anisotropy probe (WMAP) observations: angular power spectrum. Astrophys. J. Suppl. 180, 296 (2009)Penzias A.A., Wilson R.W.: A measurement of excess antenna temperature at 4,080 Mc/s. Astrophys. J. 142, 419–421 (1965)Schleicher D.R.G. et al.: Effects of primordial chemistry on the cosmic microwave background. Astron. Astrophys. 490, 521 (2008)Smoot G. et al.: Structure in the COBE differential microwave radiometer first-year maps. Astrophys. J. 396, L1–L5 (1992)Spergel D.N. et al.: First-year Wilkinson microwave anisotropy probe (WMAP) observations: determination of cosmological parameters. Astrophys. J. Suppl. 148, 175–194 (2003)StructPack: a high performance PACKage for STRUCTred Matrices. http://www.inco2.upv.es/structpack.htmlWax M., Kailath T.: Efficient inversion of Toeplitz-block Toeplitz matrix. IEEE T. Acoust. Speech. 31, 5 (1983