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Register a new userConstraining Cluster Virialization Mechanism and Cosmology using Thermal-SZ-selected clusters from Future CMB Surveys
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Added by
Srinivasan Raghunathan
Publication date
2021
fields
Physics
and research's language is
English
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We forecast the number of galaxy clusters that can be detected via the thermal Sunyaev-Zeldovich (tSZ) signals by future cosmic microwave background (CMB) experiments, primarily the wide area survey of the CMB-S4 experiment but also CMB-S4s smaller delensing survey and the proposed CMB-HD experiment. We predict that CMB-S4 will detect 75,000 clusters with its wide survey of $f_{rm sky}$ = 50% and 14,000 clusters with its deep survey of $f_{rm sky}$ = 3%. Of these, approximately 1350 clusters will be at $z ge 2$, a regime that is difficult to probe by optical or X-ray surveys. We assume CMB-HD will survey the same sky as the S4-Wide{}, and find that CMB-HD will detect $times3$ more overall and an order of magnitude more $z ge 2$ clusters than CMB-S4. These results include galactic and extragalactic foregrounds along with atmospheric and instrumental noise. Using CMB-cluster lensing to calibrate cluster tSZ-mass scaling relation, we combine cluster counts with primary CMB to obtain cosmological constraints for a two parameter extension of the standard model ($Lambda CDM+sum m_{ u}+w_{0}$). Besides constraining $sigma(w_{0})$ to $lesssim 1%$, we find that both surveys can enable a $sim 2.5-4.5sigma$ detection of $sum m_{ u}$, substantially strengthening CMB-only constraints. We also study the evolution of intracluster medium by modelling the cluster virialization ${rm v}(z)$ and find tight constraints from CMB-S4, with further factors of 3-4 improvement for CMB-HD.
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We present the weak lensing analysis of the Wide-Field Imager SZ Cluster of galaxy (WISCy) sample, a set of 12 clusters of galaxies selected for their Sunyaev-Zeldovich (SZ) effect. After developing new and improved methods for background selection and determination of geometric lensing scaling factors from absolute multi-band photometry in cluster fields, we compare the weak lensing mass estimate with public X-ray and SZ data. We find consistency with hydrostatic X-ray masses with no significant bias, no mass dependent bias and less than 20% intrinsic scatter and constrain fgas,500c=0.128+0.029-0.023. We independently calibrate the South Pole Telescope significance-mass relation and find consistency with previous results. The comparison of weak lensing mass and Planck Compton parameters, whether extracted self-consistently with a mass-observable relation (MOR) or using X-ray prior information on cluster size, shows significant discrepancies. The deviations from the MOR strongly correlate with cluster mass and redshift. This could be explained either by a significantly shallower than expected slope of Compton decrement versus mass and a corresponding problem in the previous X-ray based mass calibration, or a size or redshift dependent bias in SZ signal extraction.
The Sunyaev-Zeldovich (SZ) effect introduces a specific distortion of the blackbody spectrum of the cosmic microwave background (CMB) radiation when it scatters off hot gas in clusters of galaxies. The frequency dependence of the distortion is only independent of the cluster redshift when the evolution of the CMB radiation is adiabatic. Using 370 clusters within the redshift range $0.07lesssim zlesssim1.4$ from the largest SZ-selected cluster sample to date from the Atacama Cosmology Telescope, we provide new constraints on the deviation of CMB temperature evolution from the standard model $alpha=0.017^{+0.029}_{-0.032}$, where $T(z)=T_0(1+z)^{1-alpha}$. This result is consistent with no deviation from the standard adiabatic model. Combining it with previous, independent datasets we obtain a joint constraint of $alpha=-0.001pm0.012$.
Galaxy cluster merger shocks are the main agent for the thermalization of the intracluster medium and the energization of cosmic ray particles in it. Shock propagation changes the state of the tenuous intracluster plasma, and the corresponding signal variations are measurable with the current generation of X-ray and Sunyaev-Zeldovich (SZ) effect instruments. Additionally, non-thermal electrons (re-)energized by the shocks sometimes give rise to extended and luminous synchrotron sources known as radio relics, which are prominent indicators of shocks propagating roughly in the plane of the sky. In this short review, we discuss how the joint modeling of the non-thermal and thermal signal variations across radio relic shock fronts is helping to advance our knowledge of the gas thermodynamical properties and magnetic field strengths in the cluster outskirts. We describe the first use of the SZ effect to measure the Mach numbers of relic shocks, for both the nearest (Coma) and the farthest (El Gordo) clusters with known radio relics.
We examine the stacked thermal Sunyaev-Zeltext{}dovich (SZ) signals for a sample of galaxy cluster candidates from the Spitzer-HETDEX Exploratory Large Area (SHELA) Survey, which are identified in combined optical and infrared SHELA data using the redMaPPer algorithm. We separate the clusters into three richness bins, with average photometric redshifts ranging from 0.70 to 0.80. The richest bin shows a clear temperature decrement at 148 GHz in the Atacama Cosmology Telescope data, which we attribute to the SZ effect. All richness bins show an increment at 220 GHz, which we attribute to dust emission from cluster galaxies. We correct for dust emission using stacked profiles from Herschel Stripe 82 data, and allow for synchrotron emission using stacked profiles created by binning source fluxes from NVSS data. We see dust emission in all three richness bins, but can only confidently detect the SZ decrement in the highest richness bin, finding $M_{500}$ = $8.7^{+1.7}_{-1.3} times 10^{13} M_odot$. Neglecting the correction for dust depresses the inferred mass by 26 percent, indicating a partial fill-in of the SZ decrement from thermal dust and synchrotron emission by the cluster member galaxies. We compare our corrected SZ masses to two redMaPPer mass--richness scaling relations and find that the SZ mass is lower than predicted by the richness. We discuss possible explanations for this discrepancy, and note that the SHELA richnesses may differ from previous richness measurements due to the inclusion of IR data in redMaPPer.
The angular power spectrum of the thermal Sunyaev-Zeldovich (tSZ) effect is highly sensitive to cosmological parameters such as sigma_8 and Omega_m, but its use as a precision cosmological probe is hindered by the astrophysical uncertainties in modeling the gas pressure profile in galaxy groups and clusters. In this paper we assume that the relevant cosmological parameters are accurately known and explore the ability of current and future tSZ power spectrum measurements to constrain the intracluster gas pressure or the evolution of the gas mass fraction, f_gas. We use the CMB bandpower measurements from the South Pole Telescope and a Bayesian Markov Chain Monte Carlo (MCMC) method to quantify deviations from the standard, universal gas pressure model. We explore analytical model extensions that bring the predictions for the tSZ power into agreement with experimental data. We find that a steeper pressure profile in the cluster outskirts or an evolving f_gas have mild-to-severe conflicts with experimental data or simulations. Varying more than one parameter in the pressure model leads to strong degeneracies that cannot be broken with current observational constraints. We use simulated bandpowers from future tSZ survey experiments, in particular a possible 2000 deg^2 CCAT survey, to show that future observations can provide almost an order of magnitude better precision on the same model parameters. This will allow us to break the current parameter degeneracies and place simultaneous constraints on the gas pressure profile and its redshift evolution, for example.
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