Sunyaev-Zeldovich Power Spectrum Research Articles

Probing the physics of reionization using kinematic Sunyaev–Zeldovich power spectrum from current and upcoming cosmic microwave background surveys

ABSTRACT The patchiness in the reionization process alters the statistics of cosmic microwave background (CMB), with the kinematic Sunyaev–Zeldovich (kSZ) effect in the CMB temperature power spectrum being a notable consequence. In this work, we aim to explore the potential of future kSZ power spectrum measurements in inferring the details of the reionization process. In this pursuit, we capitalize on the recent developments in foreground mitigation techniques using the Cross-Internal Linear Combination (Cross-ILC) technique, which enables robust detection of the kSZ power spectrum with signal-to-noise ratio roughly 20σ–30σ in this decade by South pole Telescope (SPT-3G) and Simons Observatory (SO); and ≥80σ by CMB-S4 – substantially improving on the recent evidence for kSZ binned at ℓ = 3000 using SPT-SZ + SPTpol surveys. We use a fiducial kSZ power spectrum along with realistic error bars expected from the above technique for SPT-3G, SO, and CMB-S4 to constrain the parameter space for a physical model of reionization. We find that with the improved error bars it will be possible to place stringent constraints on reionization using solely the Cross-ILC recovered SPT-3G kSZ without imposing any prior on τ in the Bayesian inference. Notably, high-fidelity kSZ measurements from CMB-S4 coupled with τ measurements through LiteBIRD will enable unprecedented constraint on the midpoint of reionization with an error bar of ∼0.25 and the duration of reionization with an error bar at ∼0.21 exclusively using CMB data. This study highlights the need to capture kSZ power spectrum on a broad range of multipoles to gain insights into the inhomogeneous reionization era.

The non-thermal secondary CMB anisotropies from a cosmic distribution of radio galaxy lobes

ABSTRACT Current and upcoming high angular resolution and multifrequency experiments are well poised to explore the rich landscape of secondary cosmic microwave background (CMB) anisotropies. In this context, we compute, for the first time, the power spectrum of CMB fluctuations from a cosmological distribution of evolving lobes of giant radio galaxies. We also explicitly take into account the non-thermal electron distribution, which has important implications for the inference of the CMB angular power spectrum. We calculate the mean global non-thermal y-distortion, 〈y〉NT. For observationally reasonable distribution of the jet luminosities in the range of 1045–1047 erg s−1, we find 〈y〉NT to be less than 10−5, and hence not violating the cosmic background explorer limit as previously claimed. Using the unique spectral dependence of the non-thermal Sunyaev–Zeldovich (SZ), we show that a detection of 〈y〉NT can be within reach at the level of ≳5σ from a future Primordial Inflation Explorer (PIXIE)-like experiment provided we understand the foregrounds precisely. The total non-thermal SZ power spectrum, $C^{\mathrm{ NT}}_\ell$, from the radio lobes peaks at ℓ ∼ 3000 with an amplitude $\sim 1{{\ \rm per\ cent}}$ of thermal SZ power spectrum from galaxy clusters. A detection of the $C^{\mathrm{ NT}}_\ell$, with a PIXIE-like sensitivity experiment, can lead to ∼5σ constraint on the mass dependence of the jet luminosity with the constraint becoming at least ten times better for the proposed more ambitious CMB-HD survey. This will further lead to the tightest constraint on the central black hole mass-to-host halo mass scaling relations.

Removing the giants and learning from the crowd: A new SZ power spectrum method and revised Compton y-map analysis

ABSTRACT The Sunyaev–Zeldovich (SZ) effect provides a powerful cosmological probe, which traditionally is approached independently as cluster number count (CNC) or power spectrum (PS) analysis. Here, we devise a new method for analysing the y-map by introducing the survey completeness function, conventionally only used in the CNC analysis, in the yy-PS modelling. This provides a systematic method, based mainly on SZ observables, for obtaining two complementary y-maps, one incorporating detected/resolved clusters and the other relying only on diffuse/unresolved SZ contributions. We use the catalogue of clusters obtained in the Planck CNC analysis to define the completeness function linking these two y-maps. The split depends on the chosen signal-to-noise detection threshold, which we vary in our discussion. We carefully propagate the effect of completeness cuts on the non-Gaussian error contributions in the yy-PS analysis, highlighting the benefits of masking massive clusters. Our analysis of the Planck yy-PS for the unresolved component yields a mass bias of b = 0.15 ± 0.04, consistent with the standard value (b ≈ 0.2), in comparison to b = 0.4 ± 0.05 for the total yy-PS. We find indications for this drift being driven by the CIB-tSZ cross-correlation, which dominantly originates from clusters in the resolved component of the y-map. Another possible explanation is the presence of a mass-dependent bias, which has been theoretically motivated and can be quantified with our novel method. We furthermore find first hints for the presence of the 2-halo terms in the yy-PS. Finally, the proposed method provides a new framework for combining the complementary information of the CNC and PS analyses in upcoming SZ surveys.

Robustness of the Pairwise Kinematic Sunyaev–Zeldovich Power Spectrum Shape as a Cosmological Gravity Probe

Abstract We prove from the modified gravity (MG) galaxy/halo mock catalogs that the shape of the pairwise kinematic Sunyaev–Zeldovich (kSZ) power spectrum P kSZ has constraining power on discriminating different gravity theories on cosmological scales. By varying the effective optical depth τ T as a free parameter, we verify that the τ T-f (the linear growth rate) degeneracy in the linear theory of P kSZ is broken down by the nonlinear structure growth and the scale dependence of f in some MG theories. Equivalently speaking, the shape of P kSZ alone could be used to tightly constrain the MG theories on cosmological scales. With good knowledge of galaxy density biases, we verify that a combination of the next-generation galaxy spectroscopic redshift and CMB surveys, e.g., BOSS+CMB-S4 or DESI+CMB-S4, could potentially discriminate f(R) models from the general relativity at the ∼5σ level using the shape of the galaxy pairwise kSZ dipole P kSZ,ℓ = 1 alone, when f R0 = 10−4.

Including massive neutrinos in thermal Sunyaev Zeldovich power spectrum and cluster counts analyses

ABSTRACT We consistently include the effect of massive neutrinos in the thermal Sunyaev Zeldovich (SZ) power spectrum and cluster counts analyses, highlighting subtle dependencies on the total neutrino mass and data combination. In particular, we find that using the transfer functions for cold dark matter (CDM) + baryons in the computation of the halo mass function, instead of the transfer functions including neutrino perturbations, as prescribed in recent work, yields an ≈0.25 per cent downward shift of the σ8 constraint from tSZ power spectrum data, with a fiducial neutrino mass Σmν = 0.06 eV. In ΛCDM, with an X-ray mass bias corresponding to the expected hydrostatic mass bias, i.e. (1 − b) ≃ 0.8, our constraints from Planck SZ data are consistent with the latest results from SPT, DES-Y1, and KiDS+VIKING-450. In νΛCDM, our joint analyses of Planck SZ with Planck 2015 primary CMB yield a small improvement on the total neutrino mass bound compared to the Planck 2015 primary CMB constraint, as well as (1 − b) = 0.64 ± 0.04 (68 per cent CL). For forecasts, we find that competitive neutrino mass measurements using cosmic variance limited SZ power spectrum require masking the heaviest clusters and probing the small-scale SZ power spectrum up to ℓmax ≈ 104. Although this is challenging, we find that SZ power spectrum can realistically be used to tightly constrain intracluster medium properties: we forecast a 2 per cent determination of the X-ray mass bias by combining CMB-S4 and our mock SZ power spectrum with ℓmax = 103.

Cosmology with Thermal Sunyaev Zeldovich Power Spectrum and Cluster Counts: Consistency, Tensions and Prospects

In this proceeding I summarise the current status of cosmological constraints obtained from current SZ data, focusing on the Planck thermal SZ power spectrum and cluster counts. I discuss the consistency between Planck SZ data and other SZ cluster or galaxy surveys as well as the apparent discrepancy between SZ and CMB for the amplitude of matter clustering σ8. Finally I discuss forecasted constraints on massive neutrinos and the X-ray mass bias in the context of future SZ power spectrum measurements.

Cosmological constraints from thermal Sunyaev–Zeldovich power spectrum revisited

Thermal Sunyaev-Zeldovich (tSZ) power spectrum is one of the most sensitive methods to constrain cosmological parameters, scaling as the amplitude $\sigma_8^8$. It is determined by the integral over the halo mass function multiplied by the total pressure content of clusters, and further convolved by the cluster gas pressure profile. It has been shown that various feedback effects can change significantly the pressure profile, possibly even pushing the gas out to the virial radius and beyond, strongly affecting the tSZ power spectrum at high $l$. Energetics arguments and SZ-halo mass scaling relations suggest feedback is unlikely to significantly change the total pressure content, making low $l$ tSZ power spectrum more robust against feedback effects. Furthermore, the separation between the cosmic infrared background (CIB) and tSZ is more reliable at low $l$. Low $l$ modes are however probing very small volumes, giving rise to very large non-gaussian sampling variance errors. By computing the trispectrum contribution we identify $90<l<350$ as the minimum variance scale where the combined error is minimized. Using the measurement at this $l$ provides constraints that are almost as strong as using the entire power spectrum. We extend the work by the Planck collaboration by including a full trispectrum and feedback effects in the analysis. We perform a Markov-Chain Monte Carlo analysis over the two dimensional parameter space and find constraints on $\sigma_8$ by marginalizing over the feedback nuisance parameter.We obtain $\sigma_8 =0.820^{+0.021}_{-0.009}\left(\Omega_m/0.31\right)^{0.4}$, when fixing other parameters to Planck cosmology values. Our results suggest it is possible to obtain competitive cosmological constraints from tSZ without cluster redshift information, and that the current tSZ power spectrum shows no evidence for a low amplitude of $\sigma_8$.

CONSTRAINING PERTURBATIVE EARLY DARK ENERGY WITH CURRENT OBSERVATIONS

In this work, we study a class of early dark energy (EDE) models, in which, unlike in standard dark energy models, a substantial amount of dark energy exists in the matter-dominated era. We self-consistently include dark energy perturbations, and constrain these models using current observations. We consider EDE models in which the dark energy equation of state is at least wm ≳ −0.1 at early times, which could lead to an EDE density of up to . Our analysis shows that marginalizing over the non-DE parameters such as Ωm, H0, andns, current CMB observations alone can constrain the scale factor of transition from EDE to late-time dark energy to at ≳ 0.44 and width of transition to Δt ≲ 0.37. The equation of state at present is somewhat weakly constrained to w0 ≲ −0.6, if we allow H0 < 60 km s−1 Mpc−1. Taken together with other observations, such as SNe, Hubble Space Telescope, and Sloan Digital Sky Survey luminous red galaxies, w0 is constrained much more tightly to w0 ≲ −0.9, while redshift of transition and width of transition are also tightly constrained to at ≲ 0.19 andΔt ≲ 0.21. The evolution of the equation of state for EDE models is thus tightly constrained to ΛCDM-like behavior at low redshifts. Incorrectly assuming dark energy perturbations to be negligible leads to different constraints on the equation of state parameters—w0 ≲ −0.8, at ≲ 0.33, andΔt ≲ 0.31, thus highlighting the necessity of self-consistently including dark energy perturbations in the analysis. If we allow the spatial curvature to be a free parameter, then the constraints are relaxed to w0 ≲ −0.77, at ≲ 0.35, andΔt ≲ 0.35 with −0.014 < Ωκ < 0.031 for CMB + other observations. For perturbed EDE models, the 2σ lower limit on σ8 (σ8 ⩾ 0.59) is much lower than that in ΛCDM (σ8 ⩾ 0.72), thus raising the interesting possibility of discriminating EDE from ΛCDM using future observations such as halo mass functions or the Sunyaev–Zeldovich power spectrum.

Sunyaev-Zeldovich effect in WMAP and its effect on cosmological parameters

We use multifrequency information in first year Wilkinson microwave anisotropy probe (WMAP) data to search for the Sunyaev-Zeldovich (SZ) effect. WMAP has sufficiently broad frequency coverage to constrain the SZ effect without the addition of higher frequency data: the SZ power spectrum amplitude is expected to increase 50% from W to Q frequency band. This, in combination with the low noise in WMAP, allows us to strongly constrain the SZ contribution. We derive an optimal frequency combination of WMAP cross-spectra to extract the SZ effect in the presence of noise, cosmic microwave background (CMB), and radio point sources, which are marginalized over. We find that the SZ contribution is less than 2% (95% C.L.) at the first acoustic peak in W band. Under the assumption that the removed radio point sources are not correlated with the SZ effect this limit implies ${\ensuremath{\sigma}}_{8}&lt;1.07$ at 95% C.L. We investigate the effect on the cosmological parameters of allowing an SZ component. We run Monte Carlo Markov chains with and without an SZ component and find that the addition of the SZ effect does not affect any of the cosmological conclusions. We conclude that the SZ effect does not contaminate the WMAP CMB or change cosmological parameters, refuting the recent claims that they may be corrupted.

The hybrid SZ power spectrum: combining cluster counts and SZ fluctuations to probe gas physics

Sunyaev-Zeldovich (SZ) effect from a cosmological distribution of clusters carry information on the underlying cosmology as well as the cluster gas physics. In order to study either cosmology or clusters one needs to break the degeneracies between the two. We present a toy model showing how complementary informations from SZ power spectrum and the SZ flux counts, both obtained from upcoming SZ cluster surveys, can be used to mitigate the strong cosmological influence (especially that of sigma_8) on the SZ fluctuations. Once the strong dependence of the cluster SZ power spectrum on sigma_8 is diluted, the cluster power spectrum can be used as a tool in studying cluster gas structure and evolution. The method relies on the ability to write the Poisson contribution to the SZ power spectrum in terms the observed SZ flux counts. We test the toy model by applying the idea to simulations of SZ surveys.

Nonlinear Kinetic Sunyaev-Zeldovich Effect

We derive fully nonlinear expressions for temperature fluctuations from the kinetic Sunyaev-Zeldovich (SZ) effect, the scattering of cosmic microwave background photons off hot electrons in bulk motion. Our result reproduces the Ostriker-Vishniac effect to second order in perturbation theory but contains nonlinear corrections to the electron velocities and densities that were neglected previously. We use the recently developed halo model for nonlinear gravitational clustering to compute the nonlinear kinetic SZ power spectrum, which dominates the primary anisotropy on small angular scales.

The Impact of Cooling and Preheating on the Sunyaev-Zeldovich Effect

We use hydrodynamical simulations to assess the impact of radiative cooling and ``preheating'' on predictions for the Sunyaev-Zeldovich (SZ) effect. Cooling significantly reduces both the mean SZ signal and its angular power spectrum, while preheating can increase the mean distortion while leaving the angular power spectrum below that found in a simulation without heating or cooling. We study the relative contribution from high- and low-density gas, and we find that in the cooling model about 60% of the mean thermal distortion arises from low-overdensity gas. We find that halos dominate the thermal SZ power spectrum in all models, while in the cooling simulation the kinetic SZ power spectrum originates predominantly in lower overdensity gas.

Large‐Scale Sunyaev‐Zeldovich Effect: Measuring Statistical Properties with Multifrequency Maps

We study the prospects for extracting detailed statistical properties of the Sunyaev-Zeldovich (SZ) eUect associated with large-scale structure using upcoming multifrequency cosmic microwave background (CMB) experiments. The greatest obstacle to detecting the large-angle signal is the confusion noise pro- vided by the primary anisotropies themselves, and to a lesser degree Galactic and extragalactic fore- grounds. We employ multifrequency subtraction techniques and the latest foregrounds models to determine the detection threshold for the Boomerang, Microwave Anisotropy Probe (MAP; several kK), and Planck CMB (sub-kK) experiments. Calibrating a simpli—ed biased-tracer model of the gas pressure from recent hydrodynamic simulations, we estimate the SZ power spectrum, skewness, and bispectrum through analytic scalings and N-body simulations of the dark matter. We show that the Planck satellite should be able to measure the SZ eUect with sufficient precision to determine its power spectrum and higher order correlations, e.g., the skewness and bispectrum. Planck should also be able to detect the cross-correlation between the SZ and gravitational lensing eUect in the CMB. Detection of these eUects will help determine the properties of the as yet undetected gas, including the manner in which the gas pressure traces the dark matter. Subject headings: cosmic microwave backgroundcosmology: theory ¨ large-scale structure of universe