Non-Gaussianity in the HILC foreground-reduced three-year WMAP CMB map

A detection or nondetection of primordial non-Gaussianity in the CMB data is essential not only to test alternative models of the physics of the early universe but also to discriminate among classes of inflationary models. Given this far reaching consequences of such a non-Gaussianity detection for our understanding of the physics of the early universe, it is important to employ alternative indicators in order to have further information about the Gaussianity features of CMB that may be helpful for identifying their origins. In this way, a considerable effort has recently gone into the design of non-Gaussianity indicators, and in their application in the search for deviation from Gaussianity in the CMB data. Recently we have proposed two new large-angle non-Gaussianity indicators which provide measures of the departure from Gaussianity on large angular scales. We have used these indicators to carry out analyses of Gaussianity of the single frequency bands and of the available foreground-reduced {\it five-year} maps with and without the KQ75 mask. Here we extend and complement these studies by performing a new analysis of deviation from Gaussianity of the {\it three-year} harmonic ILC (HILC) foreground-reduced full-sky and KQ75 masked maps obtained from WMAP data. We show that this full-sky foreground-reduced maps presents a significant deviation from Gaussianity, which is brought down to a level of consistency with Gaussianity when the KQ75 mask is employed.Comment: 6 pages, 1 figure. To appear in IJMPD (2010). V2: Corrected ref.[8]

Non-Gaussianity from Baryon Asymmetry

We study a scenario that large non-Gaussianity arises from the baryon asymmetry of the Universe. There are baryogenesis scenarios containing a light scalar field, which may result in baryonic isocurvature perturbations with some amount of non-Gaussianity. As an explicit example we consider the Affleck-Dine mechanism and show that a flat direction of the supersymmeteric standard model can generate large non-Gaussianity in the curvature perturbations, satisfying the observational constraints on the baryonic isocurvature perturbations. The sign of a non-linearity parameter, f_{NL}, is negative, if the Affleck-Dine mechanism accounts for the observed baryon asymmetry; otherwise it can be either positive or negative.Comment: 25 pages, 7 figures; minor correction, references added; version to appear in JCA

Electromagnetic Cascade in the Early Universe and its Application to the Big-Bang Nucleosynthesis

We investigate the electromagnetic cascade initiated by injection of very high energy photons in the early Universe and calculate the cascade spectrum by solving a set of Boltzmann equations numerically. In the calculation we take account of Compton scattering off the background electrons and pair creation off the background nucleons as well as photon-photon processes and inverse Compton scattering. We also apply our cascade spectrum to the big bang nucleosynthesis with photo-dissociation processes due to heavy unstable particles and obtain the constraint on their lifetime and abundance.Comment: 21pages (compressed and uuencoded postscript file including 6 figures

511 keV Gamma Ray from Moduli Decay in the Galactic Bulge

We show that the $e^++e^-$ decay of a light scalar boson of mass 1-10 MeV may account for the fluxes of 511 keV gamma ray observed by SPI/INTEGRAL. We argue that candidates of such a light scalar boson is one of the string moduli or a scalar partner of the axion in a supersymmetric theory.Comment: 6 pages, no figure, we have added an appendix to describe the dilution of the moduli by the thermal inflation and some minor correction

Gravitino Production in the Inflationary Universe and the Effects on Big-Bang Nucleosynthesis

Gravitino production and decay in the inflationary universe are reexamined. Assuming that the gravitino mainly decays into a photon and a photino, we calculate the upperbound on the reheating temperature. Compared to previous works, we have essentially improved the following two points: (i) the helicity $\pm\frac{3}{2}$ gravitino production cross sections are calculated by using the full relevant terms in the supergravity lagrangian, and (ii) the high energy photon spectrum is obtained by solving the Boltzmann equations numerically. Photo-dissociation of the light elements (D, T, $^3$He, $^4$He) leads to the most stringent upperbound on the reheating temperature, which is given by ($10^{6}$--$10^{9}$)GeV for the gravitino mass 100GeV--1TeV. On the other hand, requiring that the present mass density of photino should be smaller than the critical density, we find that the reheating temperature have to be smaller than ($10^{11}$--$10^{12}$)GeV for the photino mass (10--100)GeV, irrespectively of the gravitino mass. The effect of other decay channels is also considered

Double inflation in supergravity and the primordial black hole formation

We study a double inflation model (a hybrid inflation + a new inflation) in supergravity and discuss the formation of primordial black holes (PBHs) with mass \sim 10^{-20}-10^{5}M_{\odot}. We find that in a wide range of parameter space, we obtain PBHs which amount to \Omega \simeq 1, i.e., PBH dark matter. Also, we find a set of inflation parameters which produces PBHs evaporating now. Those PBHs may be responsible for antiproton fluxes observed by the BESS experiment.Comment: 14 pages, 2 figures (RevTeX file