A Decade of WHIM Searches: Where do we Stand and Where do we Go?

TL;DR

This paper reviews a decade of research on the Warm Hot Intergalactic Medium (WHIM), updates the baryon census, and proposes observational strategies and a legacy XMM-Newton program to detect missing baryons across their temperature range.

Contribution

It provides a comprehensive review of past WHIM searches, updates the baryon census, and introduces a new observational program (URBE) to improve detection prospects.

Findings

Updated baryon census in the local Universe.

Summarized current state of WHIM detection.

Proposed a new observational strategy with XMM-Newton.

Abstract

In this article we first review the past decade of efforts in detecting the missing baryons in the Warm Hot Intergalactic Medium (WHIM) and summarize the current state of the art by updating the baryon census and physical state of the detected baryons in the local Universe. We then describe observational strategies that should enable a significant step forward in the next decade, while waiting for the step-up in quality offered by future missions. In particular we design a multi-mega-second and multiple cycle XMM-Newton legacy program (which we name the Ultimate Roaming Baryon Exploration, or URBE) aimed to secure detections of the peaks in the density distribution of the Universe missing baryons over their entire predicted range of temperatures.