Related papers: Does the small CMB quadrupole moment suggest new p…
We investigate a modification in the action of inflaton due to noncommutativity leads to a nonstandard initial vacuum and oscillatory corrections in the initial power spectrum. We show that the presence of these oscillations causes a drop…
Slow-roll inflation may simultaneously solve the horizon problem and generate a near scale-free fluctuation spectrum P(k). These two processes are intimately connected via the initiation and duration of the inflationary phase. But a recent…
The amplitudes of the quadrupole and octopole measured from the Wilkinson Microwave Anisotropy Probe (WMAP) appear to be lower than expected according to the concordance Lambda CDM cosmology. However, the pseudo-Cl estimator used by the…
A possible origin of the anomalous dip and bump in the primordial power spectrum, which are reconstructed from WMAP data corresponding to the multipole $\ell=100\sim 140$ by using the inversion method, is investigated as a consequence of…
In the standard inflationary scenario, primordial perturbations are adiabatic. The amplitudes of most types of isocurvature perturbations are generally constrained by current data to be small. If, however, there is a baryon-density…
We estimate the depolarizing effect of a primordial magnetic field upon the cosmic microwave background radiation due to differential Faraday rotation across the last scattering surface. The degree of linear polarization of the CMB is…
In this paper we investigate power spectrum of a smoothed scalar field. The smoothing leads to the regularisation of the UV divergences and can be related with the internal structure of the considered field or the space itself. We apply…
Within the standard six-parameter Lambda cold dark matter ($\Lambda$CDM) model, a $2$-$3\sigma$ tension persists between baryon acoustic oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) and observations of…
If inflation was preceded by a radiation era then at the time of inflation there will exist a decoupled thermal distribution of gravitons. Gravitational waves generated during inflation will be amplified by the process of stimulated…
In the early Universe, energy stored in small-scale density perturbations is quickly dissipated by Silk-damping, a process that inevitably generates mu- and y-type spectral distortions of the cosmic microwave background (CMB). These…
We revisit the Cosmic Microwave Background (CMB) constraints on the spatial curvature of the Universe, assessing how they change when the curvature parameter and the primordial inflationary scalar spectrum are treated consistently within…
Current measurements of the temperature and polarization anisotropy power spectra of the Cosmic Microwave Background (CMB) seem to indicate that the naive expectation for the slow-roll hierarchy within the most simple inflationary paradigm…
The Cosmic Microwave Background (CMB) power spectrum derived from the first year WMAP data demonstrates an intriguing lack of power at large scales that cannot be accounted for within the framework of the standard cosmological model. We…
We show that the thermal Sunyaev-Zeldovich effect caused by hot electrons in the Local Supercluster (LSC) can explain the abnormal quadrupole and octopole of the cosmic microwave background (CMB) that were measured by WMAP and COBE. The…
Quantum mechanical metric fluctuations during an early inflationary phase of the universe leave a characteristic imprint in the polarization of the cosmic microwave background (CMB). The amplitude of this signal depends on the energy scale…
We consider that the pre-inflation era is radiation-dominated, transiting smoothly to the inflationary era. We work out in detail the dynamics of inflaton fluctuations across the phase transition and the proper choices of initial vacuum…
[Abridged] A sharp cut-off in the primordial scalar power spectrum on large scales has been known to improve the fit to the cosmic microwave background (CMB) data when compared to the more standard, nearly scale invariant power spectrum…
The cosmic microwave background (CMB) temperature maps published by the Wilkinson Microwave Anisotropy Probe (WMAP) team are found to be inconsistent with the differential time-ordered data (TOD), from which the maps are reconstructed. The…
We consider the prospects of probing features in the primordial power spectrum with future Cosmic Microwave Background (CMB) polarization measurements. In the scope of the inflationary scenario, such features in the spectrum can be produced…
We present a new method for measuring the CMB temperature quadrupole, using large scale CMB polarization. The method exploits the fact that CMB polarization is partially sourced by the local temperature quadrupole. We link the temperature…