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arXiv 2006.15467astro-ph.COastro-ph.GA
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膜世界中的星系形成I：综述和初步结果

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

César Hernández-Aguayo, Christian Arnold, Baojiu Li, Carlton M. Baugh

备注：
18 pages, 9 figures, matches with published version
发表信息：
MNRAS, Volume 503, Issue 3, May 2021, Pages 3867-3885
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摘要：

我们进行“全物理”的流体动力学模拟星系形成正常分支Dvali-Gabadadze-Porrati（nDGP）braneworld模型使用新修改版本的{ \sc Arepo}代码和IllustrisTNG星系形成模型。我们模拟了两个nDGP模型（N5和N1），分别代表，弱和中度偏离GR，在盒子的大小$62\,h^{-1}{\rm Mpc}$和$25\,h^{-1}{\rm Mpc}$使用$2\times512^3$暗物质粒子和初始气体细胞。这使我们能够探索，第一次，重子物理学对银河系尺度的braneworld模型的修改引力和预测暗物质晕和星系演化的恒星内容，通过宇宙时间在这些模型。我们发现GR和NDGP模型之间的显着差异的气体，恒星和暗物质的功率谱和关联函数高达$\sim 25$ %的大尺度。与标准宇宙学模型（$Λ$ CDM）中重子效应的影响类似，重子效应可以对整体物质分布的聚集产生重大影响，其符号取决于尺度。通过研究这些模型中修正引力和星系反馈之间的简并性，我们发现这两种对物质聚集的物理效应可以完全分离，从而可以准确预测包含重子效应的物质功率谱，而无需运行流体动力学模拟。根据braneworld模型，我们发现与GR的差异高达$\sim15$ %的星系属性，如恒星晕质量比，星系恒星质量函数，气体分数和恒星形成率密度。第五种力的振幅会因晕内重子的存在而减小，但在$\sim0.1$乘以晕半径之后，这种减小很快就可以忽略不计了。

英文摘要：

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 {\sc Arepo} code and the IllustrisTNG galaxy formation model. We simulate two nDGP models (N5 and N1) which represent, respectively, weak and moderate departures from GR, in boxes of sizes $62\,h^{-1}{\rm Mpc}$ and $25\,h^{-1}{\rm Mpc}$ using $2\times512^3$ 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 $\sim 25$ per cent on large scales. Similar to their impact in the standard cosmological model ($Λ$CDM), 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 $\sim15$ 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 $\sim0.1$ times the halo radius.

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