Formation of compact galaxies in the Extreme-Horizon simulation

S. Chabanier, F. Bournaud, Y. Dubois, S. Codis, D. Chapon, D. Elbaz, C. Pichon, O. Bressand, J. Devriendt, R. Gavazzi, K. Kraljic, T. Kimm, C. Laigle, J. B. Lekien, G. Martin, N. Palanque-Delabrouille, S. Peirani, P. F. Piserchia, A. Slyz, M. TrebitschC. Yèche

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7 Citations (Scopus)


We present the Extreme-Horizon (EH) cosmological simulation, which models galaxy formation with stellar and active galactic nuclei (AGN) feedback and uses a very high resolution in the intergalactic and circumgalactic medium. Its high resolution in low-density regions results in smaller-size massive galaxies at a redshift of z = 2, which is in better agreement with observations compared to other simulations. We achieve this result thanks to the improved modeling of cold gas flows accreting onto galaxies. In addition, the EH simulation forms a population of particularly compact galaxies with stellar masses of 1010-11 M that are reminiscent of observed ultracompact galaxies at z 2. These objects form primarily through repeated major mergers of low-mass progenitors and independently of baryonic feedback mechanisms. This formation process can be missed in simulations with insufficient resolution in low-density intergalactic regions.

Original languageEnglish
Article numberL8
JournalAstronomy and Astrophysics
Publication statusPublished - 2020 Nov 1

Bibliographical note

Funding Information:
Acknowledgements. The Extreme-Horizon simulation was performed as a “Grand Challenge” project granted by GENCI on the AMD Rome extension of the Joliot Curie supercomputer at TGCC. We are indebted to Marc Joos, Adrien Cotte, Christine Ménaché and the whole HPC Application Team at TGCC for their efficient support. Collaborations and discussions with Bruno Thooris, Eric Armengaud, Marta Volonteri, Avishai Dekel, are warmly acknowledged. We deeply appreciate comments from Jérémy Blaizot on the Extreme Horizon project. This research used the ramses code written mainly by Romain Teyssier, the custom Hercule parallel I/O library, the kinemetry package written by Davor Krajnović, and the disperse code from Thierry Sousbie. This work was supported by the ANR 3DGasFlows (ANR-17-CE31-0017) and made use of the Horizon Cluster hosted by the Institut d’Astrophysique de Paris, run by Stéphane Rouberol. SCo’s research is partially supported by Fon-dation MERAC. TK was supported by the National Research Foundation of Korea (NRF-2017R1A5A1070354 and NRF-2020R1C1C100707911). MT is supported by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy EXC-2181/1 – 390900948 (the Heidelberg STRUCTURES Cluster of Excellence).

Publisher Copyright:
© S. Chabanier et al. 2020.

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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