If there are a large number of vacua, multi-inflation may be a more mediocre phenomenon rather than a single inflation. In the multi-inflation scenario, new inflation is most likely the last inflation, since its energy scale is naturally low. Furthermore, it may explain the observed spectral index of the cosmic microwave background radiations. We show, in this letter, that a new inflation model...

We present detections of absorption from the ground state and excited states of C I in the z = 1.9731 damped Lyα system of the QSO 0013−004. The excitation temperature between the J = 0 and J = 1 fine-structure levels of C I is 11.6 ± 1.0 K. We estimate other contributions to the excitation of the C I fine-structure levels, and use the population ratio of the excited state to the ground state t...

We investigate different types of neutrino hot dark matter with respect to structure formation and anisotropies in the cosmic microwave background radiation (CMBR). The possibility of neutrino hot dark matter produced through the decay of a heavier neutrino by the process νH → νL+φ, where φ is a scalar particle, is discussed in detail. This type of dark matter can possibly be distinguished obse...

In this paper we study the footprint of cosmic string as the topological defects in the very early universe on the cosmic microwave background radiation. We develop the method of level crossing analysis in the context of the well-known Kaiser-Stebbins phenomenon for exploring the signature of cosmic strings. We simulate a Gaussian map by using the best fit parameter given by WMAP-7 and then sup...

We report on a current investigation of the anisotropy pattern induced by cosmic strings on the cosmic microwave background radiation (MBR). We have numerically evolved a network of cosmic strings from a redshift of Z = 100 to the present and calculated the anisotropies which they induce. Based on a limited number of realizations, we have compared the results of our simulations with the observa...

We extend the formalism of the relativistic thermal and kinematic Sunyaev-Zel’dovich effects and include the polarization of the cosmic microwave background photons. We consider the situation that a cluster of galaxies is moving with a velocity ~ β ≡ ~v/c with respect to the cosmic microwave background radiation. In the present formalism, polarization of the scattered cosmic microwave backgroun...

Four billion years ago, sea-level UV exposure was more than 400 times as intense as today, the dose from solar cosmic rays was five times present levels, and galactic cosmic rays accounted for only about 10% their current contribution to sea-level radiation doses. Exposure to cosmic radiation accounts for about 10% of natural background radiation exposure today and includes dose from galactic c...