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Galaxy formation in the brane world I: overview and first results

Hernández-Aguayo, César and Arnold, Christian and Li, Baojiu and Baugh, Carlton M (2021) 'Galaxy formation in the brane world I: overview and first results.', Monthly notices of the Royal Astronomical Society, 503 (3). pp. 3867-3885.

Abstract

We carry out ‘full-physics’ hydrodynamical simulations of galaxy formation in the normal-branch Dvali–Gabadadze–Porrati (nDGP) braneworld model using a new modified version of the AREPO code and the IllustrisTNG galaxy formation model. We simulate two nDGP models (N5 and N1) that represent, respectively, weak and moderate departures from general relativity (GR), in boxes of sizes 62 and 25h−1Mpc using 2 × 5123 dark matter particles and initial gas cells. This allows us to explore, for the first time, the impact of baryonic physics on galactic scales in braneworld models of modified gravity and to make predictions on the stellar content of dark matter haloes and galaxy evolution through cosmic time in these models. We find significant differences between the GR and nDGP models in the power spectra and correlation functions of gas, stars and dark matter of up to ∼25 per cent on large scales. Similar to their impact in the standard cosmological model (Λ cold dark matter), baryonic effects can have a significant influence over the clustering of the overall matter distribution, with a sign that depends on scale. Studying the degeneracy between modified gravity and galactic feedback in these models, we find that these two physical effects on matter clustering can be cleanly disentangled, allowing for a method to accurately predict the matter power spectrum with baryonic effects included, without having to run hydrodynamical simulations. Depending on the braneworld model, we find differences compared with GR of up to ∼15 per cent in galaxy properties such as the stellar-to-halo-mass ratio, galaxy stellar mass function, gas fraction, and star formation rate density. The amplitude of the fifth force is reduced by the presence of baryons in the very inner part of haloes, but this reduction quickly becomes negligible above ∼0.1 times the halo radius.

Item Type:Article
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Available under License - Creative Commons Attribution 4.0.
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Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1093/mnras/stab694
Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2021 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:01 March 2021
Date deposited:14 July 2021
Date of first online publication:11 March 2021
Date first made open access:14 July 2021

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