Cosmic Microwave Background Data Research Articles

A GPU-accelerated viewer for HEALPix maps

HEALPix by Górskiet al. (2005) is a de-facto standard for Cosmic Microwave Background (CMB) data storage and analysis, and is widely used in current and upcoming CMB experiments. Almost all the datasets in Legacy Archive for Microwave Background Data Analysis (LAMBDA) use HEALPix as a format of choice. Visualizing the data plays important role in research, and several toolsets were developed to do that for HEALPix maps, most notably original Fortran facilities and Python integration with healpy. With the current state of GPU performance, it is now possible to visualize extremely large maps in real time on a laptop or a tablet. HEALPix Viewer described here is developed for macOS, and takes full advantage of GPU acceleration to handle extremely large datasets in real time. It compiles natively on Intel and Arm64 architectures, and uses Metal framework for high-performance GPU computations. The aim of this project is to reduce the effort required for interactive data exploration, as well as time overhead for producing publication-quality maps. Drag and drop integration with Keynote and Powerpoint makes creating presentations easy. The main codebase is written in Swift, a modern and efficient compiled language, with high-performance computing parts delegated entirely to GPU, and a few inserts in C interfacing to cfitsio library for I/O. Graphical user interface is written in SwiftUI, a new declarative UI framework based on Swift. Most common spherical projections and colormaps are supported out of the box, and the available source code makes it easy to customize the application and to add new features if desired. On a M1 Max laptop, an nside=8192 maps are processed in real time, with geometry effects rendered at 60fps in full resolution with no appreciable load to the machine. Main user-facing delays are limited to CPU-bound cfitsio load times, and sorting needed to construct Cumulative Distribution Function (CDF) estimators for statistical analysis (hidden in background queue). Overall performance improves on the current Python software stack by a factor of 3–180x depending on the task at hand.

Dark matter search with CMB: a study of foregrounds

The energy injected from dark matter annihilation and decay processes potentially raises the ionisation of the intergalactic medium and leaves visible footprints on the anisotropy maps of the cosmic microwave background (CMB). Galactic foregrounds emission in the microwave bands contaminate the CMB measurement and may affect the search for dark matter's signature. In this paper, we construct a full CMB data and foreground simulation based on the design of the next-generation ground-based CMB experiments. The foreground residual after the components separation on maps is fully considered in our data analysis, accounting for various contamination from the emission of synchrotron, thermal dust, free-free and spinning dust. We analyse the corresponding sensitivity on dark matter parameters from the temperature and polarization maps, and we find that the CMB foregrounds leave a non-zero yet controllable impact on the sensitivity. Comparing with statistics-only analysis, the CMB foreground residual leads to a factor of at most 19% weakening on energy-injection constraints, depending on the specific dark matter process and experimental configuration. Strong limits on dark matter annihilation rate and decay lifetime can be expected after foreground subtraction.

Constraints on Early Dark Energy from Isotropic Cosmic Birefringence.

Polarization of the cosmic microwave background (CMB) is sensitive to new physics violating parity symmetry, such as the presence of a pseudoscalar "axionlike" field. Such a field may be responsible for early dark energy (EDE), which is active prior to recombination and provides a solution to the so-called Hubble tension. The EDE field coupled to photons in a parity-violating manner would rotate the plane of linear polarization of the CMB and produce a cross-correlation power spectrum of E- and B-mode polarization fields with opposite parities. In this Letter, we fit the EB power spectrum predicted by the photon-axion coupling of the EDE model with a potential V(ϕ)∝[1-cos(ϕ/f)]^{3} to polarization data from Planck. We find that the unique shape of the predicted EB power spectrum is not favored by the data and obtain a first constraint on the photon-axion coupling constant, g=(0.04±0.16)M_{Pl}^{-1} (68% C.L.), for the EDE model that best fits the CMB and galaxy clustering data. This constraint is independent of the miscalibration of polarization angles of the instrument or the polarized Galactic foreground emission. Our limit on g may have important implications for embedding EDE in fundamental physics, such as string theory.

Group sparse optimization for inpainting of random fields on the sphere

Abstract We propose a group sparse optimization model for inpainting of a square-integrable isotropic random field on the unit sphere, where the field is represented by spherical harmonics with random complex coefficients. In the proposed optimization model, the variable is an infinite-dimensional complex vector and the objective function is a real-valued function defined by a hybrid of the $\ell _2$ norm and non-Lipschitz $\ell _p (0<p<1)$ norm that preserves rotational invariance property and group structure of the random complex coefficients. We show that the infinite-dimensional optimization problem is equivalent to a convexly-constrained finite-dimensional optimization problem. Moreover, we propose a smoothing penalty algorithm to solve the finite-dimensional problem via unconstrained optimization problems. We provide an approximation error bound of the inpainted random field defined by a scaled Karush–Kuhn–Tucker (KKT) point of the constrained optimization problem in the square-integrable space on the sphere with probability measure. Finally, we conduct numerical experiments on band-limited random fields on the sphere and images from Cosmic Microwave Background (CMB) data to show the promising performance of the smoothing penalty algorithm for inpainting of random fields on the sphere.

Evidence for Suppression of Structure Growth in the Concordance Cosmological Model.

We present evidence for a suppressed growth rate of large-scale structure during the dark-energy-dominated era. Modeling the growth rate of perturbations with the "growth index" γ, we find that current cosmological data strongly prefer a higher growth index than the value γ=0.55 predicted by general relativity in a flat Lambda cold dark matter cosmology. Both the cosmic microwave background data from Planck and the large-scale structure data from weak lensing, galaxy clustering, and cosmic velocities separately favor growth suppression. When combined, they yield γ=0.633_{-0.024}^{+0.025}, excluding γ=0.55 at a statistical significance of 3.7σ. The combination of fσ_{8} and Planck measurements prefers an even higher growth index of γ=0.639_{-0.025}^{+0.024}, corresponding to a 4.2σ tension with the concordance model. In Planck data, the suppressed growth rate offsets the preference for nonzero curvature and fits the data equally well as the latter model. A higher γ leads to a higher matter fluctuation amplitude S_{8} inferred from galaxy clustering and weak lensing measurements, and a lower S_{8} from Planck data, effectively resolving the S_{8} tension.

Revisiting constraints on the photon rest mass with cosmological fast radio bursts

Fast radio bursts (FRBs) have been suggested as an excellent celestial laboratory for testing the zero-mass hypothesis of the photon. In this work, we use the dispersion measure (DM)–redshift measurements of 23 localized FRBs to revisit the photon rest mass mγ . As an improvement over previous studies, here we take into account the more realistic probability distributions of DMs contributed by the FRB host galaxy and intergalactic medium (IGM) from the IllustrisTNG simulation. To better account for the systematic uncertainty induced by the choices of priors of cosmological parameters, we also combine the FRB data with the cosmic microwave background data, the baryon acoustic oscillation data, and type Ia supernova data to constrain the cosmological parameters and mγ simultaneously. We derive a new upper limit of mγ ≤ 3.8 × 10-51 kg, or equivalently mγ ≤ 2.1 × 10-15 eV/c2 (mγ ≤ 7.2 × 10-51 kg, or equivalently mγ ≤ 4.0 × 10-15 eV/c2) at 1σ (2σ) confidence level. Meanwhile, our analysis can also lead to a reasonable estimation for the IGM baryon fraction f IGM = 0.873+0.061 -0.050. With the number increment of localized FRBs, the constraints on both mγ and f IGM will be further improved. A caveat of constraining mγ within the context of the standard ΛCDM cosmological model is also discussed.

The Simons Observatory: a new open-source power spectrum pipeline applied to the Planck legacy data

We present a reproduction of the Planck 2018 angular power spectra at ℓ > 30, and associated covariance matrices, for intensity and polarization maps at 100, 143 and 217 GHz. This uses a new, publicly available, pipeline that is part of the PSpipe package. As a test case we use the same input maps, ancillary products, and analysis choices as in the Planck 2018 analysis, and find that we can reproduce the spectra to 0.1σ precision, and the covariance matrices to 10%. We show that cosmological parameters estimated from our re-derived products agree with the public Planck products to 0.1σ, providing an independent cross-check of the Planck team's analysis. Going forward, the publicly-available code can be easily adapted to use alternative input maps, data selections and analysis choices, for future optimal analysis of Planck data with new ground-based Cosmic Microwave Background data.

The D(p,γ)3H reaction at LUNA: implications in cosmology, particle physics and theoretical nuclear physics

The D(p,γ)3He cross section at low energies affects the primordial deuterium abundance, that in turn depends on fundamental cosmological parameters such as the baryon density and the amount of relativistic particles permeating the early universe. This paper discusses a new measurement of the D(p,γ)3He cross-section in the 30-280 keV energy range, performed at the Gran Sasso Laboratory (LNGS) with the LUNA facility. This measurement provides a new determination of the universal baryon density at the BBN epoch Ωb(BBN) with improved accuracy, in excellent agreement with the baryon density value derived from the Cosmic Microwave Background data Ωb(CMB). Furthermore, the LUNA result allows to better constrain the existence of dark radiation, i.e. the amount of light particles not considered in the standard model of particle physics, such as sterile neutrinos or hot axions. This paper also discusses the results of a new analysis showing that the D(p,γ)3He differential cross section is in excellent agreement with recent ab-initio theoretical calculations.

Extended analysis of neutrino-dark matter interactions with small-scale CMB experiments

We explore an extension of the standard ΛCDM model by including an interaction between neutrinos and dark matter, and making use of the ground based telescope data of the Cosmic Microwave Background (CMB) from the Atacama Cosmology Telescope (ACT). An indication for a non-zero coupling between dark matter and neutrinos (both assuming a temperature independent and T2 dependent cross-section) is obtained at the 1σ level coming from the ACT CMB data alone and when combined with the Planck CMB and Baryon Acoustic Oscillations (BAO) measurements. This result is confirmed by both fixing the effective number of relativistic degrees of freedom in the early Universe to the Standard Model value of Neff=3.044, and allowing Neff to be a free cosmological parameter. Furthermore, when performing a Bayesian model comparison, the interacting νDM (+Neff) scenario is mostly preferred over a baseline ΛCDM (+Neff) cosmology. The preferred value is then used as a benchmark and the potential implications of dark matter’s interaction with a sterile neutrino are discussed.

Cosmological constraints with the linear point from the BOSS survey

ABSTRACT The Linear Point (LP), defined as the mid-point between the baryon acoustic oscillation (BAO) peak and the associated left dip of the two-point correlation function (2PCF), ξ(s), is proposed as a new standard ruler which is insensitive to non-linear effects. In this paper, we use a Bayesian sampler to measure the LP and estimate the corresponding statistical uncertainty, and then perform cosmological parameter constraints with LP measurements. Using the Patchy mock catalogues, we find that the measured LPs are consistent with theoretical predictions at 0.6 per cent level. We find constraints with mid-points identified from the rescaled 2PCF (s2ξ) more robust than those from the traditional LP based on ξ, as the BAO peak is not always prominent when scanning the cosmological parameter space, with the cost of 2–4 per cent increase of statistical uncertainty. This problem can also be solved by an additional data set that provides strong parameter constraints. Measuring LP from the reconstructed data slightly increases the systematic error but significantly reduces the statistical error, resulting in more accurate measurements. The 1 σ confidence interval of distance scale constraints from LP measurements are 20–30 per cent larger than those of the corresponding BAO measurements. For the reconstructed Sloan Digital Sky Survey Data Release 12 data, the constraints on H0 and Ωm in a flat-Lambda cold dark matter framework with the LP are generally consistent with those from BAO. When combined with Planck cosmic microwave background data, we obtain $H_0=68.02_{-0.37}^{+0.36}$ ${\rm km}\, {\rm s}^{-1}\, {\rm Mpc}^{-1}$ and $\Omega _{\rm m}=0.3055_{-0.0048}^{+0.0049}$ with the LP.

Lensing Reconstruction from the Cosmic Microwave Background Polarization with Machine Learning

The lensing effect of the cosmic microwave background (CMB) is a powerful tool for our study of the distribution of matter in the universe. The quadratic estimator (QE) method, which is widely used to reconstruct lensing potential, has been known to be suboptimal for the low noise level polarization data from next-generation CMB experiments. To improve the performance of the reconstruction, other methods, such as the maximum-likelihood estimator and machine-learning algorithms, have been developed. In this work, we present a deep convolutional neural network model named the Residual Dense Local Feature U-net (RDLFUnet) for reconstructing the CMB lensing convergence field. By simulating lensed CMB data with different noise levels to train and test network models, we find that for noise levels less than 5 μK-arcmin, RDLFUnet can recover the input gravitational potential with a higher signal-to-noise ratio than the previous deep-learning and traditional QE methods at almost the entire observation scale.

Early Dark Energy in Type IIB String Theory

Early Dark Energy (EDE) is a promising model to resolve the Hubble Tension, that, informed by Cosmic Microwave Background data, features a generalization of the potential energy usually associated with axion-like particles. We develop realizations of EDE in type IIB string theory with the EDE field identified as either a C4 or C2 axion and with full closed string moduli stabilization within the framework of either KKLT or the Large Volume Scenario. We explain how to achieve a natural hierarchy between the EDE energy scale and that of the other fields within a controlled effective field theory. We argue that the data-driven EDE energy scale and decay constant can be achieved without any tuning of the microscopic parameters for EDE fields that violate the weak gravity conjecture, while for states that respect the conjecture it is necessary to introduce a fine-tuning. This singles out as the most promising EDE candidates, amongst several working models, the C2 axions in LVS with 3 non-perturbative corrections to the superpotential generated by gaugino condensation on D7-branes with non-zero world-volume fluxes.

Ultra-light axions and the S 8 tension: joint constraints from the cosmic microwave background and galaxy clustering

We search for ultra-light axions as dark matter (DM) and dark energy particle candidates, for axion masses 10-32 eV ≤ m a ≤ 10-24 eV, by a joint analysis of cosmic microwave background (CMB) and galaxy clustering data — and consider if axions can resolve the tension in inferred values of the matter clustering parameter S 8. We give legacy constraints from Planck 2018 CMB data, improving 2015 limits on the axion density Ωa h 2 by up to a factor of three; CMB data from the Atacama Cosmology Telescope and the South Pole Telescope marginally weaken Planck bounds at m a = 10-25 eV, owing to lower (and theoretically-consistent) gravitational lensing signals. We jointly infer, from Planck CMB and full-shape galaxy power spectrum and bispectrum data from the Baryon Oscillation Spectroscopic Survey (BOSS), that axions are, today, < 10% of the DM for m a ≤ 10-26 eV and < 1% for 10-30 eV ≤ m a ≤ 10-28 eV. BOSS data strengthen limits, in particular at higher m a by probing high-wavenumber modes (k < 0.4h Mpc-1). BOSS alone finds a preference for axions at 2.7σ, for m a = 10-26 eV, but Planck disfavours this result. Nonetheless, axions in a window 10-28 eV ≤ m a ≤ 10-25 eV can improve consistency between CMB and galaxy clustering data, e.g., reducing the S 8 discrepancy from 2.7σ to 1.6σ, since these axions suppress structure growth at the 8h -1 Mpc scales to which S 8 is sensitive. We expect improved constraints with upcoming high-resolution CMB and galaxy lensing and future galaxy clustering data, where we will further assess if axions can restore cosmic concordance.

The CMB cold spot under the lens: ruling out a supervoid interpretation

The Cosmic Microwave Background (CMB) anisotropies are thought to be statistically isotropic and Gaussian. However, several anomalies are observed, including the CMB Cold Spot, an unexpected cold ∼ 10° region with p-value ≲ 0.01 in standard ΛCDM. One of the proposed origins of the Cold Spot is an unusually large void on the line of sight, that would generate a cold region through the combination of integrated Sachs-Wolfe and Rees-Sciama effects. In the past decade extensive searches were conducted in large scale structure surveys, both in optical and infrared, in the same area for z ≲ 1 and did find evidence of large voids, but of depth and size able to account for only a fraction of the anomaly. Here we analyze the lensing signal in the Planck CMB data and rule out the hypothesis that the Cold Spot could be due to a large void located anywhere between us and the surface of last scattering. In particular, computing the evidence ratio we find that a model with a large void is disfavored compared to ΛCDM, with odds 1 : 13 (1 : 20) for SMICA (NILC) maps, compared to the original odds 56 : 1 (21 : 1) using temperature data alone.

Entanglement masquerading in the CMB

The simplest single-field inflation models capture all the relevant contributions to the patterns in the Cosmic Microwave Background (CMB) observed today. A key assumption in these models is that the quantum inflationary fluctuations that source such patterns are generated by a particular quantum state — the Bunch-Davies (BD) state. While this is a well-motivated choice from a theoretical perspective, the question arises of whether current data can rule out other, also well motivated, choices of states. In particular, as we previously demonstrated in [1], entanglement is naturally and inevitably dynamically generated during inflation given the presence of a “rolling” spectator scalar field — and the resulting entangled state will yield a primordial power spectrum with potentially measurable deviations compared to the canonical BD result. For this work we developed a perturbative framework to allow a systematic exploration of constraints on (or detection of) entangled states with Planck CMB data using Monte Carlo techniques. We have found that most entangled states accessible with our framework are consistent with the data. One would have to expand the framework to allow a greater variety of entangled states in order to saturate the Planck constraints and more systematically explore any preferences the data may have among the different possibilities.

Dark matter trigger for early dark energy coincidence

Early dark energy (EDE), whose cosmological role is localized in time around the epoch of matter-radiation equality in order to resolve the Hubble tension, introduces a new coincidence problem: why should the EDE dynamics occur near equality if EDE is decoupled from both matter and radiation? The resolution of this problem may lie in an {\it early dark sector} (EDS), wherein the dark matter mass is dependent on the EDE scalar field. Concretely, we consider a Planck-suppressed coupling of EDE to dark matter, as would naturally arise from breaking of the global $U(1)$ shift symmetry of the former by quantum gravity effects. With a sufficiently flat potential, the rise to dominance of dark matter at matter-radiation equality itself triggers the rolling and subsequent decay of the EDE. We show that this {\it trigger} EDS (tEDS) model can naturally resolve the EDE coincidence problem at the background level without any fine tuning of the coupling to dark matter or of the initial conditions. When fitting to current cosmological data, including that from the local distance ladder and the low-redshift amplitude of fluctuations, the tEDS maximum-likelihood model performs comparably to EDE for resolving the Hubble tension, achieving $H_0 =71.2$ km/s/Mpc. However, fitting the \emph{Planck} cosmic microwave background data requires a specific range of initial field positions to balance the scalar field fluctuations that drive acoustic oscillations, providing testable differences with other EDE models.

H0=69.8±1.3 km s−1 Mpc−1 , Ωm0=0.288±0.017 , and other constraints from lower-redshift, non-CMB, expansion-rate data

We use updated Type Ia Pantheon+ supernova, baryon acoustic oscillation, and Hubble parameter (now also accounting for correlations) data, as well as new reverberation-measured C IV quasar data, and quasar angular size, H II starburst galaxy, reverberation-measured Mg II quasar, and Amati-correlated gamma-ray burst data to constrain cosmological parameters. We show that these data sets result in mutually consistent constraints and jointly use them to constrain cosmological parameters in six different spatially-flat and non-flat cosmological models. Our analysis provides summary model-independent determinations of two key cosmological parameters: the Hubble constant, $H_0=69.8\pm1.3$ $\rm{km \ s^{-1} \ Mpc^{-1}}$, and the current non-relativistic matter density parameter, $\Omega_{m0}=0.288\pm0.017$. Our summary error bars are 2.4 and 2.3 times those obtained using the flat $\Lambda$CDM model and Planck TT,TE,EE+lowE+lensing cosmic microwave background (CMB) anisotropy data. Our $H_0$ value is very consistent with that from the local expansion rate based on the Tip of the Red Giant Branch data, is 2$\sigma$ lower than that from the local expansion rate based on Type Ia supernova and Cepheid data, and is 2$\sigma$ higher than that in the flat $\Lambda$CDM model based on Planck TT,TE,EE+lowE+lensing CMB data. Our data compilation shows at most mild evidence for non-flat spatial hypersurfaces, but more significant evidence for dark energy dynamics, 2$\sigma$ or larger in the spatially-flat dynamical dark energy models we study.

Thermal friction as a solution to the Hubble and large-scale structure tensions

Thermal friction offers a promising solution to the Hubble and the large-scale structure (LSS) tensions. This additional friction acts on a scalar field in the early universe and extracts its energy density into dark radiation, the cumulative effect being similar to that of an early dark energy (EDE) scenario. The dark radiation automatically redshifts at the minimal necessary rate to improve the Hubble tension. On the other hand, the addition of extra radiation to the Universe can mitigate the LSS tension. We explore this model in light of cosmic microwave background (CMB), baryon acoustic oscillation, and type Ia supernova data, including the SH0ES ${H}_{0}$ measurement and the Dark Energy Survey Y1 data release in our analysis. Our results indicate a preference for the regime where the scalar field converts to dark radiation at very high redshifts ($z\ensuremath{\gtrsim}{10}^{5}$), asymptoting effectively to an extra self-interacting radiation species rather than an EDE-like injection. In this limit, thermal friction can ease both the Hubble and the LSS tensions, but not resolve them. We find the source of this preference to be the incompatibility of the CMB data with the linear density perturbations of the dark radiation when injected at redshifts close to matter-radiation equality.

Boundless baryons: how diffuse gas contributes to anisotropic tSZ signal around simulated Three Hundred clusters

ABSTRACT Upcoming advances in galaxy surveys and cosmic microwave background data will enable measurements of the anisotropic distribution of diffuse gas in filaments and superclusters at redshift z = 1 and beyond, observed through the thermal Sunyaev–Zel’dovich (tSZ) effect. These measurements will help distinguish between different astrophysical feedback models, account for baryons that appear to be ‘missing’ from the cosmic census, and present opportunities for using locally anisotropic tSZ statistics as cosmological probes. This study seeks to guide such future measurements by analysing whether diffuse intergalactic gas is a major contributor to anisotropic tSZ signal in The Three Hundred Gizmo-Simba hydrodynamic simulations. We apply multiple different halo boundary and temperature criteria to divide concentrated from diffuse gas at z = 1, then create mock Compton- y maps for the separated components. The maps from 98 simulation snapshots are centred on massive galaxy clusters, oriented by the most prominent filament axis in the galaxy distribution, and stacked. Results vary significantly depending on the definition used for diffuse gas, indicating that assumptions should be clearly defined when claiming observations of the warm-hot intergalactic medium. In all cases, the diffuse gas is important, contributing 25–60 per cent of the tSZ signal in the far field (&amp;gt;4 h−1 comoving Mpc) from the stacked clusters. The gas 1–2 virial radii from halo centres is especially key. Oriented stacking and environmental selections help to amplify the signal from the warm-hot intergalactic medium, which is aligned but less concentrated along the filament axis than the hot halo gas.

Role of the Hubble scale in the weak lensing versus CMB tension

We explore a reparametrization of the lensing amplitude tension between weak lensing (WL) and cosmic microwave background (CMB) data and its implications for a joint resolution with the Hubble tension. Specifically, we focus on the lensing amplitude over a scale of 12 Mpc in absolute distance units using a derived parameter ${S}_{12}$ and show its constraints from recent surveys in comparison with Planck 2018. In WL alone, we find that the absolute distance convention correlates ${S}_{12}$ with ${H}_{0}$. Accounting for this correlation in the 3D space ${S}_{12}\ifmmode\times\else\texttimes\fi{}{\ensuremath{\omega}}_{m}\ifmmode\times\else\texttimes\fi{}h$ reproduces the usual levels of $2\ensuremath{\sim}3\ensuremath{\sigma}$ tension inferred from ${S}_{8}\ifmmode\times\else\texttimes\fi{}{\mathrm{\ensuremath{\Omega}}}_{m}$. Additionally, we derive scaling relations in the ${S}_{8}\ifmmode\times\else\texttimes\fi{}h$ and ${S}_{12}\ifmmode\times\else\texttimes\fi{}h$ planes that are allowed by $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ and extrapolate target scalings needed to solve the ${H}_{0}$ and lensing-amplitude tensions jointly in a hypothetical beyond-$\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ model. As a test example, we quantify how the early dark energy scenario compares with these target scalings. Useful fitting formulas for ${S}_{8}$ and ${S}_{12}$ as a function of other cosmological parameters in $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ are provided, with 1% precision.