Previous works have demonstrated that the generation of secondary CMB anisotropies due to the molecular optical depth is likely too small to be observed. In this paper, we examine additional ways in which primordial chemistry and the dark ages might influence the CMB. We present a detailed and updated chemical network and give an overview of the interactions of molecules with the CMB. We consider the optical depth due to line absorption, photoionization, photodissociation and free-free processes, and estimate the resulting changes in the CMB temperature and its power spectrum. The most promising results are obtained for the negative hydrogen ion \HM and the \HeHII molecule. The free-free process of \HM yields a relative change in the CMB temperature of up to $2\times10^{-11}$, and leads to a frequency-dependent change in the power spectrum of the order $10^{-7}$ at 30 GHz. With a change of the order $10^{-10}$ in the power spectrum, our result for the bound-free process of \HM is significantly below a previous suggestion. \HeHII efficiently scatters CMB photons and smears out primordial fluctuations, leading to a change in the power spectrum of the order $10^{-8}$. Improvements in the accuracy of future CMB experiments may thus help to constrain and finally detect these interesting signals from the dark ages of the universe.
We review and update some aspects of deuterium chemistry in the post-recombination Universe with particular emphasis on the formation and destruction of HD. We examine in detail the available theoretical and experimental data for the leading reactions of deuterium chemistry and we highlight the areas where improvements in the determination of rate coefficients are necessary to reduce the remaining uncertainties. We discuss the cooling properties of HD and the modifications to the standard cooling function introduced by the presence of the cosmological radiation field. Finally, we consider the …
We reconsider the effects of photon-graviton conversion in a primordial magnetic field upon the cosmic microwave background radiation. We argue that plasma effects make the photon-graviton conversion process negligible.
The physics of the origin and evolution of CMB anisotropies is described. I explain the idea and status of cosmic parameter estimation and follow it up with critical comments on its dependence on model assumptions and initial conditions.
We study the primordial nucleosynthesis and cosmic age in the presence of a net lepton asymmetry as well as baryon asymmetry. We explore a previously unnoted region of the parameter space in which very large baryon densities $0.1 \le Ω_b \le 1$ can be accommodated within the light-element constraints from primordial nucleosynthesis. This parameter space consists of $ν_μ$ and $ν_τ$ degeneracies with a small $ν_e$ degeneracy. Constraints from cosmic microwave background fluctuations are also discussed (orito00).
The existence of a primordial magnetic field at the last scattering surface may induce a measurable Faraday rotation in the polarization of the cosmic microwave background. We calculate the magnitude of this effect by evolving the radiative transfer equations for the microwave background polarization through the epoch of last scatter, in the presence of a magnetic field. For a primordial field amplitude corresponding to a present value of $10^{-9}{\rm G}$ (which would account for the observed galactic field if it were frozen in the pre-galactic plasma), we find a rotation angle of around $1^\c…
We study the impact of a stochastic background of primordial magnetic fields on the scalar contribution of CMB anisotropies and on the matter power spectrum. We give the correct initial conditions for cosmological perturbations and the exact expressions for the energy density and Lorentz force associated to the stochastic background of primordial magnetic fields, given a power-law for their spectra cut at a damping scale. The dependence of the CMB temperature and polarization spectra on the relevant parameters of the primordial magnetic fields is illustrated.
Phase transitions taking place during the inflationary epoch give rise to bubbles of true vacuum embedded in the false vacuum. These bubbles can imprint a distinctive signal on the Cosmic Microwave Background (CMB). We evaluate the feasibility of detecting these signatures with waveletsin CMB maps, such as those that will be made available by the European Space Agency's (ESA) Planck mission.
Primordial chemistry began in the recombination epoch when the adiabatic expansion caused the temperature of the radiation to fall below 4000 K. The chemistry of the early Universe involves the elements hydrogen, its isotope deuterium, helium with its isotopic forms and lithium. In this communication I will present results on the evolution of the primordial $H_2$ abundance for different cosmological models and the influence on the thermal decoupling.
Statistical isotropy of primordial perturbations is a common assumption in cosmology, but it is an assumption that should be tested. To this end, we develop cosmic microwave background statistics for a primordial power spectrum that depends on the direction, as well as the magnitude, of the Fourier wavevector. We first consider a simple estimator that searches in a model-independent way for anisotropy in the square of the temperature (and/or polarization) fluctuation. We then construct the minimum-variance estimators for the coefficients of a spherical-harmonic expansion of the direction-depen…
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 significantly reduced at frequencies around and below 30 GHz $(B_* /10^{-2}{\rm Gauss})^{1/2}$, where $B_*$ is the value of the primordial field at recombination. The depolarizing mechanism reduces the damping of anisotropies due to photon diffusion on small angular scales. The $l\approx 1000$ multipoles of the CMB temperature anisotropy correlation function in a…
Galactic magnetic fields are observed of order $\sim 10^{-6}G$, but their origin is not definitely known yet. In this paper we consider the primordial magnetic fields generated in the early universe and analyse their effects on the density perturbations and the CMBR anisotropy. We assume that the random magnetic fields have the power law spectrum and satisfy the force-free field condition. The peak heights of the CMBR anisotropy are shown to be shifted upward depending on the magnetic field strengths relative to the no-magnetic field case.
Alfven turbulence caused by statistically isotropic and homogeneous primordial magnetic field induces correlations in the cosmic microwave background anisotropies. The correlations are specifically between spherical harmonic modes a_{l-1,m} and a_{l+1,m}. In this paper we approach this issue from phase analysis of the CMB maps derived from the WMAP data sets. Using circular statistics and return phase mapping we examine phase correlation of Δl=2 for the primordial non-Gaussianity caused by the Alfven turbulence at the epoch of recombination. Our analyses show that such specific features from t…
We review current observational constraints on the polarization of the Cosmic Microwave Background (CMB), with a particular emphasis on detecting the signature of primordial gravitational waves. We present an analytic solution to the Polanarev approximation for CMB polarization produced by primordial gravitational waves. This simplifies the calculation of the curl, or B-mode power spectrum associated with gravitational waves during the epoch of cosmological inflation. We compare our analytic method to existing numerical methods and also make predictions for the sensitivity of upcoming CMB pola…
We derive a fast way for measuring primordial non-Gaussianity in a nearly full-sky map of the cosmic microwave background. We find a cubic combination of sky maps combining bispectrum configurations to capture a quadratic term in primordial fluctuations. Our method takes only N^1.5 operations rather than N^2.5 of the bispectrum analysis (1000 times faster for l=512), retaining the same sensitivity. A key component is a map of underlying primordial fluctuations, which can be more sensitive to the primordial non-Gaussianity than a temperature map. We also derive a fast and accurate statistic for…
Since cosmic-microwave-background (CMB) and large-scale-structure (LSS) data will shortly improve dramatically with the Microwave Anisotropy Probe (MAP) and Planck Surveyor, and the Anglo-Australian 2-Degree Field (2dF) and Sloan Digital Sky Survey (SDSS), respectively, it is timely to ask which of the CMB or LSS will provide a better probe of primordial non-gaussianity. In this paper we consider this question, using the bispectrum as a discriminating statistic. We consider several non-gaussian models and find that in each case the CMB will provide a better probe of primordial non-gaussianity.…
A stochastic magnetic field in the early Universe will produce anisotropies in the temperature and polarization of the cosmic microwave background. We derive analytic expressions for the microwave background temperature and polarization power spectra induced by vector and tensor perturbations from a power-law magnetic field. For a scale-invariant stochastic magnetic field smoothed over a comoving scale of $1 {\rm Mpc}$, the MAP satellite has the potential to constrain the comoving mean-field amplitude to be no greater than approximately $2\times10^{-9}$ G. Limits improve as the power-law slope…
It is now well known that a primordial chemistry, involving light elements produced during the nucleosynthesis period, might develop during the hydrogen post-recombination era. In particular, molecular ions and primordial molecules such as H2, HD and LiH will be produced. We summarize this primordial chemistry after the recombination epoch, and then present a simple gravitational collapse model of a cloud. The potentiality of fragmentation of this collapsing protoclouds through the thermal instability is also discussed. We suggest that this study could also be extended to the CO molecule, beca…
Measurements of the Faraday rotation of the cosmic microwave background radiation (CMBR) polarization could provide evidence for the existence of primordial magnetic fields. The Faraday rotation could also allow the study of some properties of these fields. In this paper, we calculate the angular dependence of the Faraday rotation correlator for different assumptions about the spectral index and correlation length of the magnetic field. We show that the helical part of the magnetic field does not make any contribution to the correlator. We stress the importance of the angular resolution of the…
In our recent paper (Yadav et al. 2007) we described a fast cubic (bispectrum) estimator of the amplitude of primordial non-Gaussianity of local type, f_{NL}, from a combined analysis of the Cosmic Microwave Background (CMB) temperature and E-polarization observations. In this paper we generalize the estimator to deal with a partial sky coverage as well as inhomogeneous noise. Our generalized estimator is still computationally efficient, scaling as O(N^3/2) compared to the O(N^5/2) scaling of the brute force bispectrum calculation for sky maps with N pixels. Upcoming CMB experiments are expect…
We discuss a possibility to directly reconstruct the CMB polarization field at the last scattering surface by accounting for modifications imposed by the gravitational lensing effect. The suggested method requires a tracer field of the large scale structure lensing potentials that deflected propagating CMB photons from the last scattering surface. This required information can come from a variety of observations on the large scale structure matter distribution, including convergence reconstructed from lensing shear studies involving galaxy shapes. In the case of so-called curl, or B,-modes of …
We implement and investigate a method for measuring departures from scale-invariance, both scale-dependent as well as scale-free, in the primordial power spectrum of density perturbations using cosmic microwave background (CMB) C_l data and a principal component analysis technique. The primordial power spectrum is decomposed into a dominant scale-invariant Gaussian adiabatic component plus a series of orthonormal modes whose detailed form only depends the noise model for a particular CMB experiment. However, in general these modes are localised across wavenumbers with 0.01 < k < 0.2 Mpc^-1, di…
We derive analytical formulae for the Minkowski Functions of the cosmic microwave background (CMB) and large-scale structure (LSS) from primordial non-Gaussianity. These formulae enable us to estimate a non-linear coupling parameter, f_NL, directly from the CMB and LSS data without relying on numerical simulations of non-Gaussian primordial fluctuations. One can use these formulae to estimate statistical errors on f_NL from Gaussian realizations, which are much faster to generate than non-Gaussian ones, fully taking into account the cosmic/sampling variance, beam smearing, survey mask, etc. We…
We report the results of a recent likelihood analysis combining the primordial nucleosynthesis and the BOOMERanG and MAXIMA-1 data on cosmic microwave background radiation anisotropies. We discuss the possible implications for relic neutrino background of a high value for the baryonic matter content of the universe, larger than what is expected in a standard nucleosynthesis scenario.
We investigate microwave background anisotropies in the presence of primordial magnetic fields. We show that a homogeneous field with fixed direction can amplify vector perturbations. We calculate the correlations of $δT/T$ explicitly and show that a large scale coherent field induces correlations between $a_{\ell-1,m}$ and $a_{\ell+1,m}$. We discuss constraints on amplitude and spectrum of a primordial magnetic field imposed by observations of CMB anisotropies.
Primordial chemistry began, at the recombination epoch, when the adiabatic expansion caused the temperature of the radiation to fall below 4000K. The chemistry of the early Universe involves the elements hydrogen, its isotope deuterium, helium with its isotopic forms and lithium. In this contribution I will discuss the influence of the primordial molecules on the cosmological decoupling. In the framework of the gravitational instability theory, each protostructure started as a tiny local overdensity. As long as these inhomogeneities are small, their evolution can be studied by the classical li…
Chemistry plays a particular role in astrophysics. After atomic hydrogen, helium and their ions, the Universe probably contains more mass in molecules than in any other species. Molecule formation in the early, pre-galactic Universe may have had much to do with the formation of galaxies themselves. In this context the possible interaction between primordial molecules and photons of the Cosmic Microwave Background is very important through the theoretical perspectives and constraints which could give some information on the theory of the large scale structure formation. In this paper we recall …
If the COBE detection of CMB fluctuations is used to normalize the power spectrum of primordial density fluctuations in a cold dark matter--dominated universe, early reionization is likely to result in a substantial diminution of primordial temperature fluctuations on degree scales. I argue that the reionization may be non--Gaussian because of feedback effects. Secondary fluctuations on arc--minute scales provide an important probe of the efficiency of rescattering.
Possible influence of primordial black hole (PBH) evaporations on cosmic microwave background (CMB) is investigated. The spectrum distortions of CMB from the black-body spectrum are described by the chemical potential $μ$ and the Compton parameter $y$. From COBE/FIRAS limits on $μ$ and $y$, the power law index $n$ of primordial density fluctuations and the mass fraction of PBHs $β$ are constrained by employing the peak theory for the formation process of PBHs. Constraints set here are $n < 1.304$ and $n<1.333$ in the thresholds of peaks $ζ_{\rm th} =0.7$ and $ζ_{\rm th} =1.2$, respectively, fo…
A primordial cosmological magnetic field induces Faraday rotation of the cosmic microwave background polarization. This rotation produces a curl-type polarization component even when the unrotated polarization possesses only gradient-type polarization, as expected from scalar density perturbations. We compute the angular power spectrum of curl-type polarization arising from small Faraday rotation due to a weak stochastic primordial magnetic field with a power-law power spectrum. The induced polarization power spectrum peaks at arcminute angular scales. Faraday rotation is one of the few cosmol…
We derive an upper limit of $B_0<3.4\times 10^{-9}(Ω_0h_{50}^2)^{1/2}$ Gauss on the present strength of any primordial homogeneous magnetic field. The microwave background anisotropy created by cosmological magnetic fields is calculated in the most general flat and open anisotropic cosmologies containing expansion-rate and 3-curvature anisotropies. Our limit is derived from a statistical analysis of the 4-year Cosmic Background Explorer data for anisotropy patterns characteristic of homogeneous anisotropy averaged over all possible sky orientations with respect to the COBE receiver. The limits…
It is known that, theoretically, the Rees-Sciama effect may cause arbitrarily large additional redshifts in the cosmic microwave background radiation due to transparent expanding voids having sizes comparable with the size of horizon. Therefore, again theoretically, eventual huge voids existing immediately after the recombination may essentially change the predictions of the theory of big bang nucleosynthesis. If this eventuality holds, then the dark matter can be dominantly baryonic and, simultaneously, one can be in accordance with the predictions of primordial nucleosynthesis theory. Studyi…
A primordial magnetic field in the early universe will cause Faraday rotation of the linear polarization of the cosmic microwave background generated via Compton scattering at the surface of last scattering. This rotation induces a non-zero parity-odd (B-mode) polarization component. The Wilkinson Microwave Anisotropy Probe (WMAP) 5-year data puts an upper limit on the magnitude of the B-polarization power spectrum; assuming that the B-polarization signal is totally due to the Faraday rotation effect, the upper limits on the comoving amplitude of a primordial stochastic magnetic field range fr…
Measurements of primordial non-Gaussianity ($f_{NL}$) open a new window onto the physics of inflation. We describe a fast cubic (bispectrum) estimator of $f_{NL}$, using a combined analysis of temperature and polarization observations. The speed of our estimator allows us to use a sufficient number of Monte Carlo simulations to characterize its statistical properties in the presence of real world issues such as instrumental effects, partial sky coverage, and foreground contamination. We find that our estimator is optimal, where optimality is defined by saturation of the Cramer Rao bound, if no…
We examine the polarization signal of the cosmic microwave background radiation associated with distant clusters. The polarization is induced by the Thomson scattering of microwave photons with ionized gas of clusters and contains information of quadrupole temperature anisotropies observed at the clusters. The three-dimensional map of the signal are expressed in terms of the spin-weighted harmonics for its angular dependence. Its radial dependence is expanded perturbatively with respect to the distances (equivalently redshifts) to the clusters. The independent information that we can extract o…
These lecture notes cover mainly three connected topics. In the first part we give a detailed treatment of cosmological perturbation theory. The second part is devoted to cosmological inflation and the generation of primordial fluctuations. In part three it will be shown how these initial perturbation evolve and produce the temperature anisotropies of the cosmic microwave background radiation. Comparing the theoretical prediction for the angular power spectrum with the increasingly accurate observations provides important cosmological information (cosmological parameters, initial conditions).
A primordial stochastic magnetic field will induce temperature and polarization fluctuations in the cosmic microwave background. We outline a calculation of the resulting fluctuation power spectra and present numerical results.
Cosmic microwave background (CMB) anisotropy is our richest source of cosmological information; the standard cosmological model was largely established thanks to study of the temperature anisotropies. By the end of the decade, the Planck satellite will close this important chapter and move us deeper into the new frontier of polarization measurements. Numerous ground--based and balloon--borne experiments are already forging into this new territory. Besides providing new and independent information on the primordial density perturbations and cosmological parameters, polarization measurements off…
The contribution of gravitational wave (tensor metric) and energy density (scalar metric) fluctuations to the cosmic microwave background polarization is computed by numerically solving the relativistic radiation transfer equations. We find that the tensor contribution is significant only at large angular scales (multipoles $\ell \lta 40$). For standard recombination, the tensor contribution can dominate at $\ell \lta 40$; however, the effect would be difficult to detect since the total (scalar plus tensor) polarization is $< 1$\%. For models with late reionization, the total large angular sca…
In this work I study the polarization of the Cosmic Microwave Background (CMB) induced by a cosmological background of gravitational waves (here GWs) and I discuss the enhancement effect of a possible late and fast reionization of the Universe, caused by the Hawking evaporation of primordial black holes and happening at a redshift $z\sim 20÷30$. Then, I solve the radiative Boltzmann transfer equation in the form of a second-kind Volterra integral equation, by using the analytical method of the iterated kernels: this particular method can be successfully applied when we have an exponential kern…
The combination of the first-year Wilkinson Microwave Anisotropy Probe (WMAP) data with other finer scale cosmic microwave background (CMB) experiments (CBI and ACBAR) and two structure formation measurements (2dFGRS and Lyman $α$ forest) suggest a $Λ$CDM cosmological model with a running spectral power index of primordial density fluctuations. Motivated by this new result on the index of primordial power spectrum, we present the first study on the predicted lensing probabilities of image separation in a spatially flat $Λ$CDM model with a running spectral index (RSI-$Λ$CDM model). It is shown …
The angular power spectrum estimator developed by Peebles (1973) and Hauser & Peebles (1973) has been modified and applied to the 4 year maps produced by the COBE DMR. The power spectrum of the observed sky has been compared to the power spectra of a large number of simulated random skies produced with noise equal to the observed noise and primordial density fluctuation power spectra of power law form, with $P(k) \propto k^n$. The best fitting value of the spectral index in the range of spatial scales corresponding to spherical harmonic indices $3 \leq \ell \lesssim 30$ is an apparent spectral…
In inflationary models with minimal amount of gravity waves, the primordial power spectrum of density fluctuations, $A_S^2(k)$, together with the basic cosmological parameters, completely specify the predictions for the cosmic microwave background (CMB) anisotropy and large scale structure. Here we show how we can strongly constrain both $A_S^2(k)$ and the cosmological parameters by combining the data from the Microwave Anisotropy Probe (MAP) and the galaxy redshift survey from the Sloan Digital Sky Survey (SDSS). We allow $A_S^2(k)$ to be a free function, and thus probe features in the primor…
We propose a new method for constraining a primordial homogeneous magnetic field with the cosmic microwave background. Such a field will induce an observable parity odd cross correlation between the polarization anisotropy and the temperature anisotropy by Faraday rotation. We analyze the necessary experimental features to match, and improve, current constraints of such a field by measuring this correlation.
In the framework of inflationary models with non-vacuum initial states for cosmological perturbations, we study non-Gaussian signatures on the cosmic microwave background radiation produced by a broken-scale-invariant model which incorporates a feature at a privileged scale in the primordial power spectrum.
Our goal is to study the effects of the UV radiation from the first stars, quasars and decays of the hypothetical Super Heavy Dark Matter (SHDM) particles on the formation of primordial bound objects in the Universe. We trace the evolution of a spherically symmetric density perturbation in the Lambda Cold Dark Matter ($Λ$CDM) and MOND models, solving the frequency-dependent radiative transfer equation, non-equilibrium chemistry, and one-dimensional gas hydrodynamics. We concentrate on the destruction and formation processes of the H$_2$ molecule, which is the main coolant in the primordial obj…
B-Pol is a medium-class space mission aimed at detecting the primordial gravitational waves generated during inflation through high accuracy measurements of the Cosmic Microwave Background (CMB) polarization. We discuss the scientific background, feasibility of the experiment, and implementation developed in response to the ESA Cosmic Vision 2015-2025 Call for Proposals.
We study the effect of a possible helicity component of a primordial magnetic field on the tensor part of the cosmic microwave background temperature anisotropies and polarization. We give analytical approximations for the tensor contributions induced by helicity, discussing their amplitude and spectral index in dependence of the power spectrum of the primordial magnetic field. We find that an helical magnetic field creates a parity odd component of gravity waves inducing parity odd polarization signals. However, only if the magnetic field is close to scale invariant and if its helical part is…
Our goal is to study the effects of the UV radiation from the first stars, quasars and hypothetical Super Heavy Dark Matter (SHDM) particle decays on the formation of primordial bound objects in the Universe. We trace the evolution of a spherically symmetric density perturbation in the Lambda Cold Dark Matter and MOND model, solving the frequency-dependent radiative transfer equation, non-equilibrium chemistry, and one-dimensional gas hydrodynamics. We concentrate on the destruction and formation processes of the $H_{2}$ molecule, which is the main coolant in the primordial objects.
We analyze the temperature three--point correlation function and the skewness of the Cosmic Microwave Background (CMB), providing general relations in terms of multipole coefficients. We then focus on applications to large angular scale anisotropies, such as those measured by the {\em COBE} DMR, calculating the contribution to these quantities from primordial, inflation generated, scalar perturbations, via the Sachs--Wolfe effect. Using the techniques of stochastic inflation we are able to provide a {\it universal} expression for the ensemble averaged three--point function and for the correspo…
Rotational invariance is a well-established feature of low-energy physics. Violations of this symmetry must be extremely small today, but could have been larger in earlier epochs. In this paper we examine the consequences of a small breaking of rotational invariance during the inflationary era when the primordial density fluctuations were generated. Assuming that a fixed-norm vector picked out a preferred direction during the inflationary era, we explore the imprint it would leave on the cosmic microwave background anisotropy, and provide explicit formulas for the expected amplitudes $<a_{lm}a…
I summarize four of the most important areas of uncertainty in the study of the chemistry and cooling of gas with zero or very low metallicity. These are: i) the importance and effects of HD cooling in primordial gas; ii) the importance of metal-line and dust cooling in low metallicity gas; iii) the impact of the large uncertainties that exist in the rate coefficients of several key reactions involved in the formation of H2; and iv) the effectiveness of grain surface chemistry at high redshifts.
It is often assumed that primordial perturbations are statistically isotropic, which implies, among other properties, that their power spectrum is invariant under rotations. In this article, we test this assumption by placing model-independent bounds on deviations from rotational invariance of the primordial spectrum. Using five-year WMAP cosmic microwave anisotropy maps, we set limits on the overall norm and the amplitude of individual components of the primordial spectrum quadrupole. We find that there is no significant evidence for primordial isotropy breaking, and that an eventually non-va…
Recent observations of the cosmic microwave background (CMB) have extended the measured power spectrum to higher multipoles $l\gtrsim$1000, and there appears to be possible evidence for excess power on small angular scales. The primordial magnetic field (PMF) can strongly affect the CMB power spectrum and the formation of large scale structure. In this paper, 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 PMF based on our theoretical analysis of the power excess o…
Aside from primordial gravitational instability of the cosmological fluid, various mechanisms have been proposed to generate large-scale structure at relatively late times, including, e.g., ``late-time'' cosmological phase transitions. In these scenarios, it is envisioned that the universe is nearly homogeneous at the time of last scattering and that perturbations grow rapidly sometime after the primordial plasma recombines. On this basis, it was suggested that large inhomogeneities could be generated while leaving relatively little imprint on the cosmic microwave background (MBR) anisotropy. …
We describe different methods for estimating the bispectrum of Cosmic Microwave Background data. In particular we construct a minimum variance estimator for the flat-sky limit and compare results with previously-studied frequentist methods. Application to the MAXIMA dataset shows consistency with primordial Gaussianity. Weak quadratic non-Gaussianity is characterised by a tunable parameter $f_{NL}$, corresponding to non-Gaussianity at a level $\sim 10^{-5}f_{NL}$ (ratio of non-Gaussian to Gaussian terms), and we find limits of $|f_{NL}|<950$ for the minimum-variance estimator and $|f_{NL}|<165…
A detection of the primordial gravitational wave background is considered to be the ``smoking-gun '' evidence for inflation. While super-horizon waves are probed with cosmic microwave background (CMB) polarization, the relic background will be studied with laser interferometers. The long lever arm spanned by the two techniques improves constraints on the inflationary potential and validation of consistency relations expected under inflation. If gravitational waves with a tensor-to-scalar amplitude ratio greater than 0.01 are detected by the CMB, then a direct detection experiment with a sensit…
This set of lectures provides an overview of the basic theory and phenomenology of the cosmic microwave background. Topics include a brief historical review; the physics of temperature and polarization fluctuations; acoustic oscillations of the primordial plasma; the space of inflationary cosmological models; current and potential constraints on these models from the microwave background; and constraints on inflation.
We estimate the contributions to the cosmic microwave background radiation (CMBR) power spectrum from the static and kinematic Sunyaev-Zel'dovich (SZ) effects, and from the moving cluster of galaxies (MCG) effect. We conclude, in agreement with other studies, that at sufficiently small scales secondary fluctuations caused by clusters provide important contributions to the CMBR. At $\ell \gtrsim 3000$, these secondary fluctuations become important relative to lensed primordial fluctuations. Gravitational lensing at small angular scales has been proposed as a way to break the ``geometric degener…
The primordial curvature fluctuation spectrum is reconstructed by the maximum likelihood reconstruction method using the five-year Wilkinson Microwave Anisotropy Probe data of the cosmic microwave background temperature anisotropy. We apply the covariance matrix analysis and decompose the reconstructed spectrum into statistically independent band-powers. The prominent peak off a simple power-law spectrum found in our previous analysis turn out to be a $3.3σ$ deviation. From the statistics of primordial spectra reconstructed from mock observations, the probability that a primordial spectrum inc…
The cosmological magnetic field is one of the important physical quantities which affect strongly the cosmic microwave background (CMB) power spectrum. Recent CMB observations have been extended to higher multipoles $l\gtrsim$1000, and they resultantly exhibit an excess power than the standard model prediction in cosmological theory which best fits the Wilkinson Microwave Anisotropy Probe (WMAP) data at lower multipoles $l\lesssim$900. We calculate the CMB temperature anisotropies generated by the power-law magnetic field at the last scattering surface (LSS) in order to remove the tension betw…
