Cosmic microwave background radiation can supply us some most significant parts of the information on the universe. Some researchers believe that The gravitational system cannot be decribed by the standard statistical mechanics. In this article we apply Tsallis nonextensive statistical mechanics to investigate CMB spectrum and related cosmological processes. Based on recent observational data we find that the nonextensive statistical mechanics can modify the values of related physical quantites. Since the value of physical quantites have changed, some processes, such as recombination, can be affected. We have investigated the anisotropy of the CMB for two effects: the dipole anisotropy of CMB and the Sunyaev-Zel'dovich effect. We find that the dipole anisotropy of CMB cannot be modified by the nonextensive statistical mechanics. However, the standard result of the Sunyaev-Zel'dovich effect should be modified by nonextensive statistical mechanics. In principle, future work can distinguish these effects.
We develop a method to constrain non-isotropic features of Cosmic Microwave Background (CMB) polarization, of a type expected to arise in some models describing quantum gravity effects on light propagation. We describe the expected signatures of this kind of anomalous light propagation on CMB photons, showing that it will produce a non-isotropic birefringence effect, i.e. a rotation of the CMB polarization direction whose observed amount depends in a peculiar way on the observation direction. We also show that the sensitivity levels expected for CMB polarization studies by the \emph{Planck} sa…
We show that the Cosmic Microwave Background (CMB) polarization data gathered by the BOOMERanG 2003 flight and WMAP provide an opportunity to investigate {\it in-vacuo} birefringence, of a type expected in some quantum pictures of space-time, with a sensitivity that extends even beyond the desired Planck-scale energy. In order to render this constraint more transparent we rely on a well studied phenomenological model of quantum-gravity-induced birefringence, in which one easily establishes that effects introduced at the Planck scale would amount to values of a dimensionless parameter, denoted …
We discuss the phenomenological imprints of modifications to gravity in the early universe with a specific focus on the time of recombination. We derive several interesting results regarding the effect that such modifications have on cosmological observables, especially on the driving and phasing of acoustic oscillations, observed in the CMB and BAO, as well as the weak gravitational lensing of the CMB and of galaxy shapes. This widens the pool of measurements that can be used to test gravity with present and future surveys, in particular realizing the full constraining power of the structure …
In this short note we translate the best available observational bounds on the CMB bispectrum amplitudes into constraints on a specific scale-invariant New Physics Hypersurface (NPH) model of vacuum state modifications, as first proposed by Danielsson, in general models of single-field inflation. As compared to the power spectrum the bispectrum constraints are less ambiguous and provide an interesting upper bound on the cut-off scale in general models of single-field inflation with a small speed of sound. This upper bound is incompatible with the power spectrum constraint for most of the param…
See comments. We calculate analytically an effect of the thermal Comptonization on the cosmic microwave background (CMB) photons when they propagate through galaxy clusters. We estimate a deformation of the CMB spectrum due to multiple Compton scattering of the photons off electrons of an optically-thin hot spherical plasma cloud. This new approach allows us to disentangle and determine the optical depth and the electron temperature of a galaxy cluster using the CMB observations.
We present constraints on the cosmic growth history with recent cosmological data, allowing for deviations from Lambda CDM as might arise if cosmic acceleration is due to modifications to GR or inhomogeneous dark energy. We combine measures of the cosmic expansion history, from Type 1a supernovae, baryon acoustic oscillations and the CMB, with constraints on the growth of structure from recent galaxy, CMB and weak lensing surveys along with ISW-galaxy cross-correlations. Deviations from Lambda CDM are parameterized by phenomenological modifications to the Poisson equation and the relationship …
We consider observational limits on a proposed model of the string landscape in inflation. In this scenario, effects from the decoherence of entangled quantum states in long-wavelength modes in the universe result in modifications to the Friedmann Equation and a corresponding modification to inflationary dynamics. Previous work by Holman, Mersini-Houghton, and Takahashi suggested that such effects could provide an explanation for well-known anomalies in the Cosmic Microwave Background (CMB), such as the lack of power on large scales and the "cold spot" seen by both the WMAP and Planck satellit…
Modifications of the initial-state of the inflaton field can induce a departure from Gaussianity and leave a testable imprint on the higher order correlations of the CMB and large scale structures in the Universe. We focus on the bispectrum statistics of the primordial curvature perturbation and its projection on the CMB. For a canonical single-field action the three-point correlator enhancement is localized, maximizing in the collinear limit, corresponding to enfolded or squashed triangles in comoving momentum space. We show that the available local and equilateral template are very insensiti…
We show that models of `just enough' inflation, where the slow-roll evolution lasted only $50-60$ e-foldings, feature modifications of the CMB power spectrum at large angular scales. We perform a systematic and model-independent analysis of any possible non-slow-roll background evolution prior to the final stage of slow-roll inflation. We find a high degree of universality since most common backgrounds like fast-roll evolution, matter or radiation-dominance give rise to a power loss at large angular scales and a peak together with an oscillatory behaviour at scales around the value of the Hubb…
We study the effects of modifications of gravity after Big Bang Nucleosynthesis (BBN) which would manifest themselves mainly before recombination. We consider their effects on the Cosmic Microwave Background (CMB) radiation and on the formation of large scale structure. The models that we introduce here represent all screened modifications of General Relativity (GR) which evade the local tests of gravity such as the violation of the strong equivalence principle as constrained by the Lunar Ranging experiment. We use the tomographic description of modified gravity which defines models with scree…
Alleviating the Hubble Tension with Smooth Sign-Switching Dark Energy: Full CMB Constraints with DESI and PantheonPlus
IKERBASQUE, Basque Foundation for Science（伊卡巴斯基克巴斯克科学基金会）；Department of Physics, University of the Basque Country UPV/EHU（巴斯克大学物理系）；EHU Quantum Center, University of the Basque Country UPV/EHU（巴斯克大学量子中心）；Department of Physics, Southern University of Science and Technology（南方科技大学物理系）
We investigate the effects of the presence of relic classical superhorizon inhomogeneities during inflation. This superhorizon inhomogeneity appears as a gradient locally and picks out a preferred direction. Quantum fluctuations on this slightly inhomogeneous background are generally statistical anisotropic. We find a quadrupole modification to the ordinary isotropic spectrum. Moreover, this deviation from statistical isotropy is scale-dependent, with a $\sim -1/k^2$ factor. This result implies that the statistical anisotropy mainly appears on large scales, while the spectrum on small scales r…
We address the impact of consistent modifications of gravity on the largest observable scales, focusing on relativistic effects in galaxy number counts and the cross-correlation between the matter large scale structure (LSS) distribution and the cosmic microwave background (CMB). Our analysis applies to a very broad class of general scalar-tensor theories encoded in the Horndeski Lagrangian and is fully consistent on linear scales, retaining the full dynamics of the scalar field and not assuming quasi-static evolution. As particular examples we consider self-accelerating Covariant Galileons, B…
We analyze cosmic microwave background (CMB) data taking into account the effects of a momentum dependent effective sound speed (MESS). This approach allows to study the effects of primordial entropy in a model independent way, and its implementation requires a minimal modification of existing CMB fitting numerical codes developed for single scalar field models. We adopt a phenomenological approach, and study the effects a local variation of the MESS around the scale where other analysis have shown some deviation from an approximately scale invariant curvature perturbation spectrum. We obtain …
We introduce a patch to the commonly used public codes CAMB and CosmoMC that allows the user to implement a general modification of the equations describing the growth of cosmological perturbations, while preserving the covariant conservation of the energy-momentum. This patch replaces the previously publicly released code MGCAMB, while also extending it in several ways. The new version removes the limitation of late-time-only modifications to the perturbed Einstein equations, and includes several parametrization introduced in the literature. To demonstrate the use of the patch, we obtain join…
Statistical isotropy (SI) is one of the fundamental assumptions made in cosmological model building. This assumption is now being rigorously tested using the almost full sky measurements of the CMB anisotropies. A major hurdle in any such analysis is to handle the large biases induced due to the process of masking. We have developed a new method of analysis, using the bipolar spherical harmonic basis functions, in which we semi-analytically evaluate the modifications to SI violation induced by the mask. The method developed here is generic and can be potentially used to search for any arbitrar…
Accurate computations of spectral distortions of the cosmic microwave background (CMB) are required for constraining energy release scenarios at redshifts $z\gtrsim 10^3$. The existing literature focuses on distortions that are small perturbations to the background blackbody spectrum. At high redshifts ($z\gtrsim 10^6$), this assumption can be violated, and the CMB spectrum can be significantly distorted at least during part of its cosmic evolution. In this paper, we carry out accurate thermalization computations, evolving the distorted CMB spectrum in a general, fully non-linear way, consiste…
The impact of the existence of gravitons with non-vanishing masses on the B modes of the Cosmic Microwave Background (CMB) is investigated. We also focus on putative modifications to the speed of the gravitational waves. We find that a change of the graviton speed shifts the acoustic peaks of the CMB and then could be easily constrained. For the case of massive gravity, we show analytically how the B modes are sourced in a manner differing from the massless case leading to a plateau at low $l$ in the CMB spectrum. We also study the case when there are more than one graviton, and when pressure …
We want to find the cosmological constant influence on cosmic microwave background (CMB) temperature due to moving linear cosmic strings. Considering the space-time metric of a linear cosmic string in an accelerated expanding universe, the Gott-Kaiser-Stebbins (GKS) effect, as an important mechanism in producing temperature discontinuity in the CMB, is considered and its modification due to the effect of the cosmological constant is calculated. The result shows that a positive cosmological constant (i.e. the presence of cosmic strings in an accelerated expanding universe) weakens the discontin…
Calculations of the Cosmic Microwave Background lensing power implemented into the standard cosmological codes such as CAMB and CLASS usually treat the surface of last scatter as an infinitely thin screen. However, since the CMB anisotropies are smoothed out on scales smaller than the diffusion length due to the effect of Silk damping, the photons which carry information about the small-scale density distribution come from slightly earlier times than the standard recombination time. The dominant effect is the scale dependence of the mean redshift associated with the fluctuations during recombi…
The effects on CMB power spectra and bispectra from the polarization rotation and its correlations with temperature and E-polarization
University of Chinese Academy of Sciences（中国科学院大学）；Interdisciplinary Center for Theoretical Study, University of Science and Technology of China（中国科学技术大学理论中心）；Peng Huanwu Center for Fundamental Theory（彭桓武理论中心）
We test General Relativity (GR) using current cosmological data: the cosmic microwave background (CMB) from WMAP5 (Komatsu et al. 2009), the integrated Sachs-Wolfe (ISW) effect from the cross-correlation of the CMB with six galaxy catalogs (Giannantonio et al. 2008), a compilation of supernovae Type Ia (SNe) including the latest SDSS SNe (Kessler et al. 2009), and part of the weak lensing (WL) data from CFHTLS (Fu et al. 2008, Kilbinger et al. 2009) that probe linear and mildly non-linear scales. We first test a model where the effective Newton's constant, mu, and the ratio of the two gravitat…
The fundamental properties of the photon have deep impact on the astrophysical processes that involve it, like the inverse Compton scattering of CMB photon by energetic electrons residing within galaxy cluster atmospheres, usually referred to as the Sunyaev-Zel'dovich effect (SZE). We calculate the combined constraints on the photon decay time and mass by studying the impact of the modified CMB spectrum, as recently calculated (Heeck 2013), on the SZE of galaxy clusters. We analyze the modifications of the SZE as produced by photon decay effects. We study in details the frequency regimes where…
We show that a direct coupling between a chameleon-like scalar field and photons can give rise to a modified Sunyaev-Zel'dovich (SZ) effect in the Cosmic Microwave Background (CMB). The coupling induces a mixing between chameleon particles and the CMB photons when they pass through the magnetic field of a galaxy cluster. Both the intensity and the polarization of the radiation are modified. The degree of modification depends strongly on the properties of the galaxy cluster such as magnetic field strength and electron number density. Existing SZ measurements of the Coma cluster enable us to pla…
In models of inflation obtained from string compactification, moduli vacuum misalignment leads to an epoch in the post-inflationary history of the universe when the energy density is dominated by cold moduli particles. This effect leads to a modification in the number of $e$-foldings ($N_{\rm pivot}$) between horizon exit of the CMB modes and the end of inflation. Taking Kähler moduli inflation as a prototype, the shift in $e$-foldings turns out to be a function of the model parameters which also determines the inflationary observables. We analyse this scenario numerically using publicly avail…
In this paper we study in detail the effect of our recently proposed model of parity and charge-parity (PCP) violating varying alpha on the Cosmic Microwave Background (CMB) photon passing through the intra galaxy-cluster medium (ICM). The ICM is well known to be composed of magnetized plasma. According to our model, the polarization and intensity of the CMB would be affected when traversing through the ICM due to non-trivial scalar photon interactions. We have calculated the evolution of such polarization and intensity collectively, known as the stokes parameters of the CMB photon during its …
Scalar fields provide attractive modifications of pre-BBN cosmology, which have interesting implications for dark matter abundances. We analyse the effect of these modifications on the number of e-foldings between horizon exit of CMB modes and the end of inflation $(N_k)$, and examine the consequences for inflationary predictions of various models. We find significant effects in the predictions in the $(n_s, r)$ plane. For a large part of the parameter space, the shift in $N_k$ is positive; this ameliorates the tension of $m^{2} φ^{2}$ and natural inflation with data.
The small-scale crisis, discrepancies between observations and N-body simulations, may imply suppressed matter fluctuations on subgalactic distance scales. Such a suppression could be caused by some early-universe mechanism (e.g., broken scale invariance during inflation), leading to a modification of the primordial power spectrum at the onset of the radiation-domination era. Alternatively, it may be due to nontrivial dark-matter properties (e.g., new dark-matter interactions or warm dark matter) that affect the matter power spectrum at late times, during radiation domination, after the pertur…
Measurements of the Hubble parameter from the distance ladder are in tension with indirect measurements based on the cosmic microwave background (CMB) data and the inverse distance ladder measurements at 3-4 $σ$ level. We consider phenomenological modification to the timing and width of the recombination process and show that they can significantly affect this tension. This possibility is appealing, because such modification affects both the distance to the last scattering surface and the calibration of the baryon acoustic oscillations (BAO) ruler. Moreover, because only a very small fraction …
We study the cosmological signatures of Invisibly Annihilating Dark Matter (IAnDM), where DM annihilates into dark radiation particles that are decoupled from the Standard Model (SM). In the simple benchmark model we consider here, such invisible annihilation determines the relic abundance of DM via dark thermal freeze-out. We demonstrate that IAnDM may reveal itself through observable, novel signatures that are correlated: scale-dependent $ΔN_\text{eff}$ (number of extra effective neutrinos) in the Cosmic Microwave Background (CMB) spectrum due to DM residual annihilation, while the phase of …
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 study based on the latest Planck release suggests that P(k) has a hard cutoff, k_min > 0, inconsistent with this conventional picture. Here we demonstrate quantitatively that most---perhaps all---slow-roll inflationary models fail to accommodate this minimum cutoff. We show that the small parameter `epsilon' must be > 0.9 throughout the inflationary period t…
The anomalous lack of large angle temperature correlations has been a surprising feature of the cosmic microwave background (CMB) since first observed by COBE-DMR and subsequently confirmed and strengthened by the Wilkinson Microwave Anisotropy Probe. This anomaly may point to the need for modifications of the standard model of cosmology or may indicate that our Universe is a rare statistical fluctuation within that model. Further observations of the temperature auto-correlation function will not elucidate the issue; sufficiently high precision statistical observations already exist. Instead, …
In this review we present a comprehensive discussion of peculiar velocity field measured recently on very large scales with a novel method using X-ray galaxy clusters as tracers. The measurement is based on the kinematic component of the Sunyaev-Zeldovich (KSZ) effect produced by Compton scattering of cosmic microwave background (CMB) photons off the hot intracluster gas, and uses a large catalog of X-ray selected clusters and all-sky CMB maps obtained with the WMAP satellite. The method probes the dipole of the CMB temperature field evaluated at the cluster positions and within the apertures …
New interactions of neutrinos can stop them from free streaming in the early Universe even after the weak decoupling epoch. This results in the enhancement of the primordial gravitational wave amplitude on small scales compared to the standard $Λ$CDM prediction. In this paper we calculate the effect of dark matter neutrino interactions in CMB tensor $B$-modes spectrum. We show that the effect of new neutrino interactions generates a scale or $\ell$ dependent imprint in the CMB $B$-modes power spectrum at $\ell \gtrsim 100$. In the event that primordial $B$-modes are detected by future experime…
Non-Planckian (NP) spectral modifications of the CMB radiation spectrum can be produced due to the existence of a non-zero value of the plasma frequency at the recombination epoch. We present here an analysis of NP effects on the radio cosmological background and we derive, for the first time, predictions of their amplitude on three different observables: the CMB spectrum, the Sunyaev-Zel'dovich (SZ) effect in cosmic structures, and the 21-cm background temperature brightness change. We find that NP effect can manifest in the CMB spectrum at $ν\simlt 400$ MHz as a drastic cut-off in the CMB in…
In this work we examine the impact of our motion with respect to the CMB rest frame on statistics of CMB maps by examining the one-, two-, three- and four- point statistics of simulated maps of the CMB and Sunyaev-Zeldovich (SZ) effects. We validate boosting codes by comparing their outcomes for temperature and polarization power spectra up to $\ell \simeq 6000$. We derive and validate a new analytical formula for the computation of the boosted power spectrum of a signal with a generic frequency dependence. As an example we show how this increases the boosting correction to the power spectrum …
The temperature fluctuations and polarization of the Cosmic Microwave Background (CMB) are now a well-known probe of the Universe at an infant age of 400,000 years. During the transit to us from the surface of last scattering, the CMB photons are expected to undergo modifications induced by the intervening large-scale structure. Among the expected secondary effects is the weak gravitational lensing of the CMB by the foreground dark matter distribution. We derive a quadratic estimator that uses the non-Gaussianities generated by the lensing effect at the four-point function level to extract the…
