paper

Prospects for detecting the circum- and intergalactic medium in X-ray absorption using the extended intracluster medium as a backlight

arXiv:2311.10062 · doi:10.1093/mnras/stad3554

Abstract

The warm-hot plasma in cosmic web filaments is thought to comprise a large fraction of the gas in the local Universe. So far, the search for this gas has focused on mapping its emission, or detecting its absorption signatures against bright, point-like sources. Future, non-dispersive, high spectral resolution X-ray detectors will, for the first time, enable absorption studies against extended objects. Here, we use the Hydrangea cosmological hydrodynamical simulations to predict the expected properties of intergalactic gas in and around massive galaxy clusters, and investigate the prospects of detecting it in absorption against the bright cores of nearby, massive, relaxed galaxy clusters. We probe a total of projections from the simulation volumes, finding directions with a total column density cm. The strongest absorbers are typically shifted by km/s with respect to the rest frame of the cluster they are nearest to. Realistic mock observations with future micro-calorimeters, such as the Athena X-ray Integral Field Unit or the proposed Line Emission Mapper (LEM) X-ray probe, show that the detection of cosmic web filaments in O VII and O VIII absorption against galaxy cluster cores will be feasible. An O VII detection with a significance can be achieved in ks with Athena for most of the galaxy clusters considered. The O VIII detection becomes feasible only with a spectral resolution of around eV, comparable to that envisioned for LEM.

arXiv comment17 pages, 10 figures, 4 tables, accepted for publication in MNRAS

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