Detecting shocked intergalactic gas with X-ray and radio observations

¹ Dipartimento di Fisica e Astronomia, Universitá di Bologna, Via Gobetti 93/2, 40122 Bologna, Italy
e-mail: franco.vazza@hs.uni-hamburg.de
² Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
³ Istituto di Radioastronomia, INAF, Via Gobetti 101, 40122 Bologna, Italy
⁴ INAF, Osservatorio di Astrofisica e Scienza dello Spazio, Via Pietro Gobetti 93/3, 40129 Bologna, Italy
⁵ INFN, Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
⁶ Swiss Plasma Center, EPFL, SB SPC Station 13, 1015 Lausanne, Switzerland

Received: 9 March 2019
Accepted: 8 May 2019

Abstract

Detecting the thermal and non-thermal emission from the shocked cosmic gas surrounding large-scale structures represents a challenge for observations, as well as a unique window into the physics of the warm-hot intergalactic medium. In this work, we present synthetic radio and X-ray surveys of large cosmological simulations in order to assess the chances of jointly detecting the cosmic web in both frequency ranges. We then propose best observing strategies tailored for existing (LOFAR, MWA, and XMM) or future instruments (SKA-LOW and SKA-MID, Athena, and eROSITA). We find that the most promising targets are the extreme peripheries of galaxy clusters in an early merging stage, where the merger causes the fast compression of warm-hot gas onto the virial region. By taking advantage of a detection in the radio band, future deep X-ray observations will probe this gas in emission, and help us to study plasma conditions in the dynamic warm-hot intergalactic medium with unprecedented detail.