Formation of compact galaxies in the Extreme-Horizon simulation

S. Chabanier (1, 2) , F. Bournaud (1, 2) , Y. Dubois (3) , S. Codis (3, 4) , D. Chapon (1) , D. Elbaz (2) , C. Pichon (3, 4, 5) , O. Bressand (6, 7) , J. Devriendt (8) , R. Gavazzi (3) , K. Kraljic (9) , T. Kimm (10) , C. Laigle (3) , J.-B. Lekien (6, 7) , G. Martin (11, 12) , N. Palanque-Delabrouille (1) , S. Peirani (13, 14) , P.-F. Piserchia (6, 7) , A. Slyz (8) , M. Trebitsch (15, 16) , C. Yèche (1)

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
3 IAP - Institut d'Astrophysique de Paris
4 IPHT - Institut de Physique Théorique - UMR CNRS 3681
5 KIAS - Korean Institute of Advanced Studies
6 DAM/DIF - DAM Île-de-France
7 LIHPC - Laboratoire en Informatique Haute Performance pour le Calcul et la simulation
8 University of Oxford
9 ROE - Royal Observatory Edinburgh
10 Yonsei University
11 Steward Observatory
12 KASI - Korea Astronomy and Space Science Institute
13 LAGRANGE - Joseph Louis LAGRANGE
14 Observatoire de la Côte d'Azur
15 MPIA - Max-Planck-Institut für Astronomie
16 ZAH - Zentrum für Astronomie der Universität Heidelberg

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.

Mots clés: galaxies: formation; galaxies: evolution; galaxies: high-redshift; galaxies: structure; methods: numerical

Domaines: Astrophysique [astro-ph]

S. Chabanier, F. Bournaud, Y. Dubois, S. Codis, D. Chapon, et al.. Formation of compact galaxies in the Extreme-Horizon simulation. Astronomy and Astrophysics - A&A, 2020, 643, pp.L8. ⟨10.1051/0004-6361/202038614⟩. ⟨cea-02988983⟩