Multi-wavelength mock observations of the WHIM in a simulated galaxy cluster

TL;DR

This paper presents multi-wavelength synthetic observations of a simulated galaxy cluster to study the elusive warm-hot intergalactic medium (WHIM) and compare it with observational data, aiding future detection efforts.

Contribution

It introduces a novel numerical post-processing method with radiative transfer to generate realistic multi-wavelength maps of the WHIM in simulated galaxy clusters.

Findings

Broad agreement with previous estimates of gas components.

Synthetic maps match observational data, guiding future observations.

Analysis confirms the detectability of WHIM in multiple wavelengths.

Abstract

About half of the expected total baryon budget in the local Universe is `missing'. Hydrodynamical simulations suggest that most of the missing baryons are located in a mildly overdense, warm-hot intergalactic medium (WHIM), which is difficult to be detected at most wavelengths. In this paper we explore multi-wavelength synthetic observations of a massive galaxy cluster developed in a full Eulerian-AMR cosmological simulation. A novel numerical procedure is applied on the outputs of the simulation, which are post-processed with a full-radiative transfer code that allows to compute the change of the intensity at any frequency along the null-geodesic of photons. We compare the emission from the whole inter-galactic medium (IGM) and from the WHIM component (defined as the gas with a temperature in the range $10^5-10^7$ K) at three observational bands associated to thermal X-rays, thermal and kinematic Sunyaev-Zel'dovich effect, and radio emission. The synthetic maps produced by this procedure could be directly compared with existing observational maps and could be used as a guide for future observations with forthcoming instruments. The analysis of the different emissions associated to a high-resolution galaxy cluster is in broad agreement with previous simulated and observational estimates of both gas components.