Refereed journal article or data article (A1)

An EAGLE view of the missing baryons

List of Authors: Tuominen T, Nevalainen J, Tempel E, Kuutma T, Wijers N, Schaye J, Heinämäki Pekka, Bonamente M, Veena P Ganeshaiah


Publication year: 2021

Journal: Astronomy and Astrophysics

Journal name in source: ASTRONOMY & ASTROPHYSICS

Journal acronym: ASTRON ASTROPHYS

Volume number: 646

Number of pages: 20

ISSN: 0004-6361

eISSN: 1432-0746


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Context. A significant fraction of the predicted baryons remain undetected in the local Universe. We adopted the common assumption that a large fraction of the missing baryons correspond to the hot (log T(K) = 5.5-7) phase of the warm-hot intergalactic medium (WHIM). We base our missing baryons search on the scenario whereby the WHIM has been heated up via accretion shocks and galactic outflows, and it is concentrated towards the filaments of the cosmic web.
Aims. Our aim is to improve the observational search for the poorly detected hot WHIM.
Methods. We detected the filamentary structure within the EAGLE hydrodynamical simulation by applying the Bisous formalism to the galaxy distribution. To test the reliability of our results, we used the MMF/NEXUS+ classification of the large-scale environment of the dark matter component in EAGLE. We then studied the spatio-thermal distribution of the hot baryons within the extracted filaments.
Results. While the filaments occupy only approximate to 5% of the full simulation volume, the diffuse hot intergalactic medium in filaments amounts to approximate to 23%-25% of the total baryon budget, or approximate to 79%-87% of all the hot WHIM. The optimal filament sample, with a missing baryon mass fraction of approximate to 82%, is obtained by selecting Bisous filaments with a high galaxy luminosity density. For these filaments, we derived analytic formulae for the radial gas density and temperature profiles, consistent with recent Planck Sunyaev-Zeldovich and cosmic microwave background lensing observations within the central r approximate to 1 Mpc.
Conclusions. Results from the EAGLE simulation suggest that the missing baryons are strongly concentrated towards the filament axes. Since the filament finding methods used here are applicable to galaxy surveys, a large fraction of the missing baryons can be localised by focusing the observational efforts on the central similar to 1 Mpc regions of the filaments. To optimise the observational signal, it is beneficial to focus on the filaments with the highest galaxy luminosity densities detected in the optical data.

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Last updated on 2021-24-06 at 11:48