Mapping the relativistic electron gas temperature across the sky

Abstract

With increasing sensitivity, angular resolution, and frequency coverage, future cosmic microwave background (CMB) experiments like PICO will allow us to access new information about galaxy clusters through the relativistic thermal Sunyaev-Zeldovich (SZ) effect. We will be able to map the temperature of relativistic electrons across the entire sky, going well beyond a simple detection of the relativistic SZ effect by cluster stacking methods that currently define the state-of-the-art. Here, we propose a new map-based approach utilizing SZ-temperature moment expansion and constrained-ILC methods to extract electron gas temperature maps from foreground-obscured CMB data. This delivers a new independent map-based observable, the electron temperature power spectrum $T_{\mathrm{e}}^{yy}(\ell )$, which can be used to constrain cosmology in addition to the Compton-$y$ power spectrum $C_{\ell }^{yy}(\ell )$ . We find that PICO has the required sensitivity, resolution, and frequency coverage to accurately map the electron gas temperature of galaxy clusters across the full sky, covering a broad range of angular scales. Frequency-coverage at $\nu \gtrsim 300\mathrm{GHz}$ plays an important role for extracting the relativistic SZ effect in the presence of foregrounds. For Coma, PICO will allow us to directly reconstruct the electron temperature profile using the relativistic SZ effect. Coma's average electron temperature will be measured to $10\sigma$ significance after foreground removal using PICO. Low-angular resolution CMB experiment like LiteBIRD could achieve $2\sigma$ to $3\sigma$ measurement of the electron temperature of this largest cluster. Our analysis highlights a new spectroscopic window into the thermodynamic properties of galaxy clusters and the diffuse electron gas at large angular scales.

17 pages, 18 figures, updated to match version accepted by MNRAS

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Cited by in corpus (19)

• The Atacama Cosmology Telescope: Component-separated maps of CMB temperature and the thermal Sunyaev-Zel'dovich effect
• Peeling off foregrounds with the constrained moment ILC method to unveil primordial CMB $B$-modes
• Relativistic SZ temperature scaling relations of groups and clusters derived from the BAHAMAS and MACSIS simulations
• Combining ILC and moment expansion techniques for extracting average-sky signals and CMB anisotropies
• A multi-simulation study of relativistic SZ temperature scalings in galaxy clusters and groups
• Removing the giants and learning from the crowd: a new SZ power spectrum method and revised Compton $y$-map analysis
• Understanding matched filters for precision cosmology
• Teaching neural networks to generate Fast Sunyaev Zel'dovich Maps
• Percent-level constraints on baryonic feedback with spectral distortion measurements
• Cosmology with the thermal-kinetic Sunyaev-Zel'dovich effect
• Mitigating the impact of the CIB on galaxy cluster SZ detection with spectrally constrained matched filters
• Impact of Dust on Spectral Distortion Measurements of the Cosmic Microwave Background
• Leverage on small-scale primordial non-Gaussianity through cross-correlations between CMB $E$-mode and $\mu$-distortion anisotropies
• Least response method to separate CMB spectral distortions from foregrounds
• Importance of intracluster scattering and relativistic corrections from tSZ effect with Cosmic Infrared Background
• Atacama Large Aperture Submillimeter Telescope (AtLAST) Science: Resolving the Hot and Ionized Universe through the Sunyaev-Zeldovich effect
• Breaking degeneracies with the Sunyaev-Zeldovich full bispectrum
• Relativistic SZ maps and electron gas temperature spectroscopy
• A new approach of estimating the Galactic thermal dust and synchrotron polarized emission template in the microwave bands