The Santa Fe Light Cone Simulation Project: II. The Prospects for Direct Detection of the WHIM with SZE Surveys

TL;DR

This paper evaluates the potential for detecting the Warm-Hot Intergalactic Medium (WHIM) via Sunyaev-Zeldovich effect surveys using simulations, highlighting the sensitivity improvements needed for successful detection with current and future instruments.

Contribution

It provides estimates of the sensitivity required for detecting WHIM with SZE surveys and discusses the roles of thermal and kinematic SZE signals in such detections.

Findings

Modest sensitivity increases can make WHIM detectable in SZE surveys.

Kinematic SZE can dominate thermal SZE in certain conditions, aiding detection.

No unique features found in thermal SZE power spectrum for WHIM detection.

Abstract

Detection of the Warm-Hot Intergalactic Medium (WHIM) using Sunyaev-Zeldovich effect (SZE) surveys is an intriguing possibility, and one that may allow observers to quantify the amount of "missing baryons" in the WHIM phase. We estimate the necessary sensitivity for detecting low density WHIM gas with the South Pole Telescope (SPT) and Planck Surveyor for a synthetic 100 square degree sky survey. This survey is generated from a very large, high dynamic range adaptive mesh refinement cosmological simulation performed with the Enzo code. We find that for a modest increase in the SPT survey sensitivity (a factor of 2-4), the WHIM gas makes a detectable contribution to the integrated sky signal. For a Planck-like satellite, similar detections are possible with a more significant increase in sensitivity (a factor of 8-10). We point out that for the WHIM gas, the kinematic SZE signal can sometimes dominate the thermal SZE where the thermal SZE decrement is maximal (150 GHz), and that using the combination of the two increases the chance of WHIM detection using SZE surveys. However, we find no evidence of unique features in the thermal SZE angular power spectrum that may aid in its detection. Interestingly, there are differences in the power spectrum of the kinematic SZE, which may not allow us to detect the WHIM directly, but could be an important contaminant in cosmological analyses of the kSZE-derived velocity field. Corrections derived from numerical simulations may be necessary to account for this contamination.