The apparent alignment of the cosmic microwave background multipoles on large scales challenges the standard cosmological model. Scalar field inflation is isotropic and cannot account for the observed alignment. We explore the imprints, a non-standard spinor driven inflation would leave on the cosmic microwave background anisotropies. We show it is natural to expect an anisotropic inflationary expansion of the Universe which has the effect of suppressing the low multipole amplitude of the primordial power spectrum, while at the same time to provide the usual inflationary features.
Cosmic microwave background (CMB) observations provide in principle a high-precision test of models which are motivated by M theory. We set out the framework of a program to compute the tensor anisotropies in the CMB that are generated in braneworld models. In the simplest approximation, we show the braneworld imprint as a correction to the power spectra for standard temperature and polarization anisotropies.
We discuss the effect of the time evolution of extra dimensions on CMB anisotropies and large-scale structure formation. We study the impact of scalar fields in a low-energy effective description of a general class of brane world models on the temperature anisotropy power spectrum. We show that when the coupling between these scalar fields and matter evolves over cosmological timescales, current observations of the CMB anisotropies can constrain primordial values of the fields in a manner complementary to local, late-time tests of gravity. We also present the effect of these fields on the pola…
The metric around straight arbitrarily-oriented cosmic strings forming a stationary junction is obtained at the linearized level. It is shown that the geometry is flat. The sum rules for lensing by this configuration and the anisotropies of the CMB are obtained.
We calculate the full second-order radiation transfer function for Cosmic Microwave Background anisotropies on large angular scales in a flat universe filled with matter and cosmological constant. It includes (i) the second-order generalization of the Sachs-Wolfe effect, and of (ii) both the early and late Integrated Sachs-Wolfe effects, (iii) the contribution of the second-order tensor modes, and is valid for a generic set of initial conditions specifying the level of primordial non-Gaussianity.
Large-scale magnetic fields can affect scalar cosmological perturbations whose evolution is described in the conformally Newtonian gauge and within the tight coupling approximation. The magnetized curvature perturbations present after matter radiation equality (and prior to decoupling) are computed in terms of an appropriate transfer matrix allowing a general estimate of the Sachs-Wolfe plateau. From the observation that CMB initial conditions should be (predominantly) adiabatic, the contribution of the magnetic field intensity can be constrained.
Possible effects of large-scale magnetic fields on the Cosmic Microwave Background (CMB) are reviewed. Depending on the specific branch of the spectrum of plasma excitations, magnetic fields are treated either within a two-fluid plasma description or within an effective (one-fluid) approach. The uniform field approximation is contrasted with the fully inhomogeneous field approximation. It is argued that the interplay between CMB physics and large-scale magnetic fields will represent a rather interesting cross-disciplinary arena along the next few years.
This paper introduces a systematic treatment of the linear theory of scalar gravitational perturbations in the presence of a fully inhomogeneous magnetic field. The analysis is conducted both in the synchronous and in the conformally Newtonian gauges. The cosmological plasma is assumed to be composed of cold dark mattter, baryons, photons, neutrinos. The problem of super-horizon initial conditions for the fluid variables of the various species and for the coupled system of Boltzmann-Einstein equations is discussed in the presence of an inhomogeneous magnetic field. The tight coupling approxima…
We provide an analytical approach to the second-order Cosmic Microwave Background (CMB) anisotropies generated by the non-linear dynamics taking place at last scattering. We study the acoustic oscillations of the photon-baryon fluid in the tight coupling limit and we extend at second-order the Meszaros effect. We allow for a generic set of initial conditions due to primordial non-Gaussianity and we compute all the additional contributions arising at recombination. Our results are useful to provide the full second-order radiation transfer function at all scales necessary for establishing the le…
We show that deviations of the quantum state of the inflaton from the thermal vacuum of inflation may leave an imprint in the CMB anisotropies. The quantum dynamics of the inflaton in such a state produces corrections to the inflationary fluctuations, which may be observable. Because these effects originate from IR physics below the Planck scale, they will dominate over any trans-Planckian imprints in any theory which obeys decoupling. Inflation sweeps away these initial deviations and forces its quantum state closer to the thermal vacuum. We view this as the quantum version of the cosmic no-h…
The curl (B) modes of cosmic microwave background (CMB) polarization anisotropies are a unique probe of the primordial background of inflationary gravitational waves (IGWs). Unfortunately, the B-mode polarization anisotropies generated by gravitational waves at recombination are confused with those generated by the mixing of gradient-mode (E-mode) and B-mode polarization anisotropies as CMB photons propagate through the Universe and are gravitationally lensed. We describe here a method for delensing CMB polarization anisotropies using observations of anisotropies in the cosmic 21-cm radiation …
We generalize the treatment of inflationary perturbations to deal with the non-Markovian colored noise emerging from any realistic approach to stochastic inflation. We provide a calculation of the power-spectrum of the gauge-invariant comoving curvature perturbation to first order in the slow-roll parameters. Properly accounting for the constraint that our local patch of the Universe is homogeneous on scales just above the present Hubble radius, we find a blue tilt of the power-spectrum on the largest observable scales, in agreement with the WMAP data which show an unexpected suppression of th…
We use Nambu-Goto numerical simulations to compute the cosmic microwave background (CMB) temperature anisotropies induced at arcminute angular scales by a network of cosmic strings in a Friedmann-Lemaitre-Robertson-Walker (FLRW) expanding universe. We generate 84 statistically independent maps on a 7.2 degree field of view, which we use to derive basic statistical estimators such as the one-point distribution and two-point correlation functions. At high multipoles, the mean angular power spectrum of string-induced CMB temperature anisotropies can be described by a power law slowly decaying as …
The vector perturbations induced on the brane by gravitational waves propagating in the bulk are studied in a cosmological framework. Cosmic expansion arises from the brane motion in a non-compact five-dimensional anti-de Sitter spacetime. By solving the vector perturbation equations in the bulk, for generic initial conditions, we find that they give rise to growing modes on the brane in the Friedmann-Lema\^ıtre era. Among these modes, we exhibit a class of normalizable perturbations, which are exponentially growing with respect to conformal time on the brane. The presence of these modes is, a…
The COBE satellite has discovered anisotropies in the cosmic microwave background (CMB) consistent with a scale invariant spectrum of density perturbations. As reviewed in this lecture, topological defect models of structure formation generically produce such a spectrum. We give a summary of the cosmic string and global texture models, focusing on distinct observational signatures in large-scale structure surveys and in the microwave background. It is shown that the amplitude of the CMB quadrupole detected by COBE is in good agreement with the predictions of the cosmic string model.
A brief outline of the current status of CMB anisotropies and what they might mean, heavily biased towards the perspective of Berkeley theorists. Based on a talk presented at the 17th Texas Symposium on Relativistic Astrophysics held in Munich, December 1994.
Nonlinear gravitational effects of large-scale inhomogeneities on Cosmic Microwave Background (CMB) anisotropies are studied. based on the relativistic second-order theory of perturbations in nonzero-Lambda flat cosmological models, which has been analytically derived by the present author, and on the second-order formula of CMB anisotropies derived by Mollerach and Matarrese. In this paper we derive the components of the CMB anisotropy power spectra in the range of l = 1 -22 which are caused by asymmetric local inhomogeneities on scales of 300 Mpc. Using our results it is found that there is …
We propose an evolutional scenario of the universe which starts from quantum states with conformal invariance, passing through the inflationary era, and then makes transition to the conventional Einstein space-time. The space-time dynamics is derived from the renormalizable higher-derivative quantum gravity developed on the basis of a renormalizable conformal gravity in four dimensions. Based on the linear perturbation theory in the inflationary background, we simulate evolutions of gravitational scalar, vector and tensor perturbations, and evaluate the spectra at the transition point located …
In this talk, I review some recent work on cosmic microwave background (CMB) anisotropies in an open universe. I emphasize that the observed CMB anisotropies are still consistent with a low value of $Ω$, and I address the question of whether future CMB measurements will be able to provide information on the geometry of the Universe.
Possible signatures of primordial magnetic fields on the Cosmic Microwave Background (CMB) temperature and polarization anisotropies are reviewed. The signals that could be searched for include excess temperature anisotropies particularly at small angular scales below the Silk damping scale, B-mode polarization, and non-Gaussian statistics. A field at a few nG level produces temperature anisotropies at the 5 micro Kelvin level, and B-mode polarization anisotropies 10 times smaller, and is therefore potentially detectable via the CMB anisotropies. An even smaller field, with B_0 < 0.1 nG, could…
This is a review of the theory of CMB anisotropies, an updated version of a course given at the troisieme cycle de la Suisse Romande. An introduction to gauge invariant cosmological perturbation theory is given and the theory CMB anisotropies is develiped in this context. Simple analytical approximations for the acoustic peak positions for adiabatic and isocurvature perturbations are derived. Silk damping is discussed by an analytic approximation. A short description of the present status of observations and parameter estimation followed by a critical discussion terminate the review. The full …
We investigate the one loop effective potential of inflation in a standard model of chaotic inflation. The leading one loop corrections to the effective inflaton potential are evaluated in the quasi de Sitter background, and we estimate the one loop correction to the two-point function of the inflaton perturbations in the Hartree approximation. In this approximation, the one loop corrections depends on the total number of e-foldings of inflation and the maximal effect is estimated to be a correction to the power spectrum of a few percent. However, such a correction may be difficult to disentan…
The origin of CMB polarization is reviewed. Special emphasis is placed on the cosmological information encoded in it: the nature of primordial fluctuations, the connection with the inflation paradigm. Insights into more recent epochs are also discussed: early reionization and high redshift matter distribution from CMB lensing.
The ten's of micro-Kelvin variations in the temperature of the cosmic microwave background (CMB) radiation across the sky encode a wealth of information about the Universe. The full-sky, high-resolution maps of the CMB that will be made in the next decade should determine cosmological parameters to unprecedented precision and sharply test inflation and other theories of the early Universe.
We use numerical simulation of cosmological reionization to calculate the secondary CMB anisotropies in a representative flat low density cosmological model. We show that the kinetic Sunyaev-Zel'dovich effect (scattering off of moving electrons in the ionized intergalactic medium) is dominated by the nonlinear hydrodynamic and gravitational evolution of the density and velocity fields, rather than the detailed distribution of the ionization fraction (``patchy reionization'') on all angular scales. Combining our results with the recent calculation of secondary CMB anisotropies by Springel et al…
This article is a written and modified version of a talk presented at the conference `A Century of Cosmology' held at San Servolo, Venice, Italy, in August 2007. The talk focuses on some of the cosmology history leading to the discovery and exploitation of Cosmic Microwave Background (CMB) Radiation anisotropies. We have made tremendous advances first in the development of the techniques to observe these anisotropies and in observing and interpreting them to extract their contained cosmological information. CMB anisotropies are now a cornerstone in our understanding of the cosmos and our futur…
Thomson scattering of the Cosmic Microwave Background (CMB) on moving electrons in the outflows of Lyman Break Galaxies (LBGs) at redshifts 2-8 contributes to the small-scale CMB anisotropies. The net effect produced by each outflow depends on its level of deviation from spherical symmetry, caused either by an anisotropic energy injection from the nuclear starburst or quasar activity, or by an inhomogeneous intergalactic environment. We find that for plausible outflow parameters consistent with spectroscopic observations of LBGs, the induced CMB anisotropies on arcminute scales reach up to $\s…
We address the extended problem of component separation for CMB applications when a mixture of both astrophysical and instrumental components are present in the observations, and show how standard methods can be adapted to handle this more complex inversion problem.
We study the possible contribution of a stochastic gravitational wave background to the anisotropy of the cosmic microwave background (CMB) in cold and mixed dark matter (CDM and MDM) models. We test this contribution against recent detections of CMB anisotropy at large and intermediate angular scales. Our likelihood analysis indicates that models with blue power spectra ($n \simeq 1.2$) and a tensor to the scalar quadrupole ratio of $R = C_2^T /C_2^S \sim 2$ are most consistent with the anisotropy data considered here. We find that by including the possibility of such background in CMB data a…
A novel primordial spectrum with a dynamical scale of quantum gravity origin is proposed to explain the sharp fall off of the angular power spectra at low multipoles in the COBE and WMAP observations. The spectrum is derived from quantum fluctuations of the scalar curvature in a renormalizable model of induced gravity. This model describes the very early universe by the conformal field fluctuating about an inflationary background with the expansion time constant of order of the Planck mass.
We investigate the cosmic variance of the skewness of the cosmic microwave background (CMB) anisotropies in an inflationary model which leads to the baryon isocurvature scenario for the cosmic structure formation. In this model, the baryon number fluctuations are given by a sinusoidal function of a random Gaussian field. We find that the skewness is very small in comparison with that of the fluctuations which obey Gaussian statistics.
We consider a network of topological defects which can partly decay into neutrinos, photons, baryons, or Cold Dark Matter. We find that the degree-scale amplitude of the cosmic microwave background (CMB) anisotropies as well as the shape of the matter power spectrum can be considerably modified when such a decay is taken into account. We conclude that present predictions concerning structure formation by defects might be unreliable.
We study the large scale power spectrum of gravitational wave perturbations of the microwave background in the context of single-bubble open inflation models. We compute the ratio of tensor to scalar contributions to the CMB anisotropies as a function of $Ω_0$, the spectral index $n_S$ and the tunneling parameter $2πGS_1/H$. We find that gravitational wave anisotropies can be very large at small values of this tunneling parameter. We also consider the contribution of supercurvature and bubble wall modes and find constraints on the parameters of open inflation models from the observed temperatu…
We examine the extent to which galactic and extragalactic foregrounds can hamper the detection of primordial Cosmic Microwave Background (CMB) anisotropies. We limit our discussion to intermediate angular scales, $10^{\prime}\lsim θ\lsim 2^{\circ}$, since many current as well as future experiments have been designed to map CMB anisotropies at these angular scales. In fact, scales of $\gsim 10^{\prime}$ are of crucial importance to test both the conditions in the early Universe and current theories of the gravitational collapse.
We have searched the 1st-year WMAP W-Band CMB anisotropy map for evidence of cosmic strings. We have set a limit of $δ= 8 πG μ/ c^2 < 8.2 \times 10^{-6}$ at 95% CL for statistical search for a significant number of strings in the map. We also have set a limit using the uniform distribution of strings model in the WMAP data with $δ= 8 πG μ/ c^2 < 7.34 \times 10^{-5}$ at 95% CL. And the pattern search technique we developed here set a limit $δ= 8 πG μ/ c^2 < 1.54 \times 10^{-5}$ at 95% CL.
We study the CMB constraints on two Dark Energy models described by scalar fields with different Lagrangians, namely a Klein-Gordon and a Born-Infeld field. The speed of sound of field fluctuations are different in these two theories, and therefore the predictions for CMB and structure formation are different. Employing the WMAP data on CMB, we make a likelihood analysis on a grid of theoretical models. We constrain the parameters of the models and compute the probability distribution functions for the equation of state. We show that the effect of the different sound speeds affects the low mul…
The advent of high resolution cosmic microwave background (CMB) experiments now allows studies on the temperature fluctuations at scales corresponding to few arcminutes and below. Though the reported excess power at $\ell \sim 2000 - 6000$ by CBI and BIMA is roughly consistent with a secondary contribution resulting from the Sunyaev-Zeldovich effect, this requires a higher normalization for the matter power spectrum than measured by other means. In addition to a local red-shift contribution, another strong possibility for anisotropies at very small scales involve non-standard aspects of inflat…
While the major contribution to the Cosmic Microwave Background (CMB) anisotropies are the sought-after primordial fluctuations produced at the surface of last scattering, other effects produce secondary fluctuations at lower redshifts. These secondary fluctuations must be carefully accounted for, in order to isolate primordial fluctuations. In addition, they are interesting in their own right, since they provide a wealth of information on the geometry and local properties of the universe. Here, I survey the different sources of secondary anisotropies and extragalactic foregrounds of the CMB. …
We consider cosmic microwave background (CMB) anisotropy in models with quintessence taking into account of isocurvature fluctuation in the quintessence. It is shown that, if the primordial fluctuation of the quintessence has a correlation with the adiabatic density fluctuations, CMB angular power spectrum $C_l$ at low multipoles can be suppressed without affecting $C_l$ at high multipoles. Possible scenario of generating correlated mixture of the quintessence and adiabatic fluctuations is also discussed.
We study scalar mode perturbations (magnetosonic waves) induced by a helical stochastic cosmological magnetic field and derive analytically the corresponding cosmic microwave background (CMB) temperature and polarization anisotropy angular power spectra. We show that the presence of a stochastic magnetic field, or an homogeneous magnetic field, influences the acoustic oscillation pattern of the CMB anisotropy power spectrum, effectively acting as a reduction of the baryon fraction. We find that the scalar magnetic energy density perturbation contribution to the CMB temperature anisotropy is sm…
We present an alternative scenario for cosmic structure formation where initial fluctuations are due to Kalb-Ramond axions produced during a pre-big bang phase of inflation. We investigate whether this scenario, where the fluctuations are induced by seeds and therefore are of isocurvature nature, can be brought in agreement with present observations by a suitable choice of cosmological parameters. We also discuss several observational signatures which can distinguish axion seeds from standard inflationary models.
I review the basic theory of the cosmic microwave background anisotropies in adiabatic cold dark matter cosmologies. The latest observational results on the CMB power spectrum are consistent with the simplest inflationary models and indicate that the Universe is close to spatially flat with a nearly scale invariant fluctuation spectrum. We are also beginning to see interesting constraints on the density of CDM, with a best fit value of omega_c = Omega_c h^2 of about 0.1. The CMB constraints, when combined with observations of distant Type Ia supernovae, are converging on a Lambda-dominated Uni…
We discuss ability of the harmonic pattern of peaks in the CMB angular power spectrum to test inflation. By studying robust features of alternate models, which must all be isocurvature in nature, we reveal signatures unique to inflation. Inflation thus could be validated by the next generation of experiments.
The effect of gravitational lensing on cosmic microwave background (CMB) anisotropies is investigated using the power spectrum approach. The lensing effect can be calculated in any cosmological model by specifying the evolution of gravitational potential. Previous work on this subject is generalized to a non-flat universe and to a nonlinear evolution regime. Gravitational lensing cannot change the gross distribution of CMB anisotropies, but it may redistribute the power and smooth the sharp features in the CMB power spectrum. The magnitude of this effect is estimated using observational constr…
Tangled, primordial cosmic magnetic fields create small rotational velocity perturbations on the last scattering surface (LSS) of the cosmic microwave background radiation (CMBR). Such perturbations can contribute significantly to the CMBR temperature and polarization anisotropies at large l > 1000 or so, like the excess power detected by the CBI experiment. The magnetic contribution can be distinguished from most conventional signals, as they lead to CMBR polarization dominated by the odd parity, B-type signal. Experiments like DASI and WMAP have detected evidence for CMBR polarization at sma…
The primordial magnetic field (PMF) can strongly affect the cosmic microwave background (CMB) power spectrum and the formation of large scale structure. In this presentation, we calculate the CMB temperature anisotropies generated by including a power-law magnetic field at the photon last scattering surface (PLSS). We then deduce an upper limit on the primordial magnetic field based upon our theoretical analysis of the power excess on small angular scales. We have taken into account several important effects such as the modified matter sound speed in the presence of a magnetic field. An upper …
We present the computation of the full system of Boltzmann equations at second-order describing the evolution of the photon, baryon and cold dark matter fluids. These equations allow to follow the time evolution of the Cosmic Microwave Background (CMB) anisotropies at second-order at all angular scales from the early epoch, when the cosmological perturbations were generated, to the present through the recombination era. This paper sets the stage for the computation of the full second-order radiation transfer function at all scales and for a a generic set of initial conditions specifying the le…
I describe briefly the Cosmic Microwave Background (hereafter CMB) physics which explains why high accuracy observations of its spatial structure are a unique observational tool both for the determination of the global cosmological parameters and to constrain observationally the physics of the early universe. I also briefly survey the many experiments which have measured the anisotropies of the CMB and led to crucial advances in observational Cosmology. The somewhat frantic series of new results has recently culminated with the outcome of the WMAP satellite which confirmed earlier results, set…
In a universe reionized in patches, the Doppler effect from Thomson scattering off free electrons generates secondary cosmic microwave background (CMB) anisotropies. For a simple model with small patches and late reionization, we analytically calculate the anisotropy power spectrum. Patchy reionization can, in principle, be the main source of anisotropies on arcminute scales. On larger angular scales, its contribution to the CMB power spectrum is a small fraction of the primary signal and is only barely detectable in the power spectrum with even an ideal, i.e. cosmic variance limited, experime…
The Cosmic Microwave Background fluctuations provide a powerful probe of the dark ages of the universe through the imprint of the secondary anisotropies associated with the reionisation of the universe and the growth of structure. We review the relation between the secondary anisotropies and and the primary anisotropies that are directly generated by quantum fluctuations in the very early universe. The physics of secondary fluctuations is described, with emphasis on the ionisation history and the evolution of structure. We discuss the different signatures arising from the secondary effects in …
By decomposing the damping tail of CMB anisotropies into a series of transfer functions representing individual physical effects, we provide ingredients that will aid in the reconstruction of the cosmological model from small-scale CMB anisotropy data. We accurately calibrate the model-independent effects of diffusion and reionization damping which provide potentially the most robust information on the background cosmology. Removing these effects, we uncover model-dependent processes such as the acoustic peak modulation and gravitational enhancement that can help distinguish between alternate …
We perform detailed calculations of cosmic microwave background (CMB) anisotropies in a CDM-dominated open universe with primordial adiabatic density perturbations for a variety of reionization histories. We show that to a great extent, the CMB anisotropies depend only on the geometry of the Universe, which in a matter dominated universe is determined by $Ω$, and the optical depth to the surface of last scattering. In particular, the location of the primary Doppler peak depends primarily on $Ω$ and is fairly insensitive to the other unknown parameters, such as $Ω_b$, $h$, $Λ$, and the shape of…
We present an alternative scenario for cosmic structure formation where initial fluctuations are due to Kalb-Ramond axions produced during a pre-big bang phase of inflation. We investigate whether this scenario, where the fluctuations are induced by seeds and therefore are of isocurvature nature, can be brought in agreement with present observations by a suitable choice of cosmological parameters. We also discuss several observational signatures which can distinguish axion seeds from standard inflationary models. We finally discuss the gravitational wave background induced in this model and we…
Based on the second-order nonlinear theory of perturbations in non-zero Λflat cosmological models, we study the gravitational effects of local inhomogeneities on cosmic microwave background (CMB) anisotropies. As the local inhomogeneities we consider firstly large-scale dipole and quadruple distributions of galaxies around us and next an isolated cluster-scale matter distribution. It is found that, due to the second-order integral Sachs-Wolfe effect, the north-south asymmetry of CMB anisotropies and non-Gaussian signatures (in terms of scale-dependent estimators of kurtosis) in a spot-like obj…
Thomson scattering of CMBR temperature anisotropies will cause the spectrum of the CMBR to differ from blackbody even when one resolves all anisotropies. A formalism for computing the anisotropic and inhomogeneous spectral distortions of intensity and polarization is derived in terms of Lorentz invariant central moments of the temperature distribution. The formalism is non-perturbative, requiring neither small anisotropies nor small metric or matter inhomogeneities; but it does assume cold electrons. The low order moments are not coupled to the higher order moments allowing one to truncate the…
We generalize the total angular momentum method for computing Cosmic Microwave Background anisotropies to Friedman-Robertson-Walker (FRW) spaces with arbitrary geometries. This unifies the treatment of temperature and polarization anisotropies generated by scalar, vector and tensor perturbations of the fluid, seed, or a scalar field, in a universe with constant comoving curvature. The resulting formalism generalizes and simplifies the calculation of anisotropies and, in its integral form, allows for a fast calculation of model predictions in linear theory for any FRW metric.
We present preliminary results of an analysis into the effects of primordial voids on the cosmic microwave background (CMB). We show that an inflationary bubble model of void formation predicts excess power in the CMB angular power spectrum that peaks between 2000 < l < 3000. Therefore, voids that exist on or close to the last scattering surface at the epoch of decoupling can contribute significantly to the apparent rise in power on these scales recently detected by the Cosmic Background Imager (CBI).
We address the problem of map-making with data from the Planck Surveyor High Frequency Instrument, with an emphasis on the understanding and modelling of instrumental effects, and in particular that of sidelobe straylight. We propose a map-making method which takes advantage of the very special properties of the Planck scanning strategy along circular scans.
Second-order power spectra of Cosmic Microwave Background (CMB) anisotropies due to random primordial perturbations at the matter dominant stage are studied, based on the relativistic second-order theory of perturbations in flat cosmological models and on the second-order formula of CMB anisotropies derived by Mollerach and Matarrese. So far the second-order integrated Sachs-Wolfe effect has been analyzed using the three-point correlation or bispectrum. In this paper we derive the second-order term of power spectra given using the two-point correlation of temperature fluctuations. The second-o…
We present a new, more powerful and accurate, analytic treatment of cosmic microwave background (CMB) anisotropies in the weakly coupled regime. Three applications are presented: gravitational redshifts in a time dependent potential, the Doppler effect in reionized scenarios, and the Vishniac effect. The Vishniac effect can dominate primary anisotropies at small angles even in late and minimally reionized models in flat dark-matter dominated universes with Harrison-Zel'dovich initial conditions. The techniques developed here refine previous calculations yielding a larger coherence angle for th…
We first develop a method to calculate a complete set of mode functions which describe the quantum fluctuations generated in one-bubble open inflation models. We consider two classes of models. One is a single scalar field model proposed by Bucher, Goldhaber and Turok and by us as an example of the open inflation scinario, and the other is a two-field model such as the ``supernatural'' inflation proposed by Linde and Mezhlumian. In both cases we assume the difference in the vacuum energy density between inside and outside the bubble is negligible. There are two kinds of mode functions. One kin…
