Mapping "out-of-the-box" the properties of the baryons in massive halos

M. Angelinelli; S. Ettori; K. Dolag; F. Vazza; A. Ragagnin

doi:10.1051/0004-6361/202244068

paper

Mapping "out-of-the-box" the properties of the baryons in massive halos

arXiv:2206.08382 · doi:10.1051/0004-6361/202244068

Abstract

We study the distributions of the baryons in massive halos ( $M_{v i r} > 1 0^{13} h^{- 1} M_{⊙}$ ) in the $M a g n e t i c u m$ suite of Smoothed Particle Hydrodynamical cosmological simulations, out to the unprecedented radial extent of $10 R_{500, c}$ . We confirm that, under the action of non-gravitational physical phenomena, the baryon mass fraction is lower in the inner regions ( $< R_{500, c}$ ) of increasingly less massive halos, and rises moving outwards, with values that spans from 51% (87%) in the regions around $R_{500, c}$ to 95% (100%) at $10 R_{500, c}$ of the cosmological value in the systems with the lowest (highest; $M_{v i r} \sim 5 \times 1 0^{14} h^{- 1} M_{⊙}$ ) masses. The galaxy groups almost match the gas (and baryon) fraction measured in the most massive halos only at very large radii ( $r > 6 R_{500, c}$ ), where the baryon depletion factor $Y_{bar} = f_{bar} / (Ω_{b} / Ω_{m})$ approaches the value of unity, expected for "closed-box" systems. We find that both the radial and mass dependency of the baryon, gas, and hot depletion factors are predictable and follow a simple functional form. The star mass fraction is higher in less massive systems, decreases systematically with increasing radii, and reaches a constant value of $Y_{star} \approx 0.09$ , where also the gas metallicity is constant, regardless of the host halo mass, as a result of the early ( $z > 2$ ) enrichment process.

Submitted to A&A; 9 pages, 6 figures

Mapping "out-of-the-box" the properties of the baryons in massive halos

Abstract

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