Summary
The Extreme Horizon cosmological simulation of our universe is a Grand Challenge project hosted at TGCC supercomputing center (CEA) in 2020 and used ~50 million hours of CPU time on the Joliot Curie supercomputer.
Interacive map of a 50x50x5 Mpc projected data of the Extreme Horizon simulation at $Z\simeq 2$. The available data channels for visualization are the gas density, entropy, metallicity and velocity with an additional overlay of gas velocity streamlines.Introduction
Early-type galaxies (ETGs) at redshifts of $z >1.5$ are much more compact than nearby ones (Daddi et al. 2005). At stellar masses about $10^{11} \; \Msun$, they typically have half-mass radii of 0.7-3 kpc, which is about three times smaller than nearby ellipticals with similar masses (van der Wel et al. 2014). Compact radii are typically accompanied by steep luminosity profiles and high Sersic indices (van Dokkum & Brammer 2010; Carollo et al. 2013). Star-forming galaxies (SFGs) also decrease in size with increasing redshift (e.g., Kriek et al. 2009; Dutton et al. 2011). In addition, the CANDELS survey has discovered a population of very compact SFGs at $z\simeq 2$, that is, so-called "blue nuggets" (Barro et al. 2013; Williams et al. 2014), which have stellar masses of $10^{10-11} \; \Msun$ and unusually small effective radii around 2 kpc and sometimes even below 1 kpc. Compact SFGs have high comoving densities, of about $10^{-4} \; \textrm{Mpc}^{-3}$ for stellar masses above $10^{10} \; \Msun$ and $10^{-5} \; \textrm{Mpc}^{-3}$ above $10^{11} \; \Msun$ (Wang et al. 2019). Also, SFGs at $z\simeq 2$ often have very compact gas and star formation distributions (Elbaz et al. 2018).
A number of processes have been proposed to explain the formation of compact galaxies, ranging from early formation in a compact Universe (Lilly & Carollo 2016) and the compaction of initially extended galaxies (Zolotov et al. 2015) and up through processes that may include galaxy mergers, disk instabilities (Bournaud et al. 2007a; Dekel & Burkert 2014), triaxial haloes (Tomassetti et al. 2016), accretion of counter-rotating gas (Danovich et al. 2015), and gas return from a low-angular momentum fountain (Elmegreen et al. 2014).
The Extreme-Horizon (EH) cosmological simulation models galaxy-formation processes with the same approach as Horizon-AGN (Dubois et al. 2014) and with a substantially increased resolution in the intergalactic and circumgalactic medium (IGM and CGM). The properties of massive galaxies in the Extreme Horizon simulation and the origin of their compactness are discused here. The results of this simulation on the formation of compact galaxies are published in Chabanier 2020.
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Acknowledgements
This work was granted access to the HPC resources of TGCC under the allocation 2019-A0070402192 made by GENCI and a Grand Challenge project granted by GENCI on the AMD-Rome extension of the Joliot-Curie supercomputer at TGCC. This research is part Horizon-UK projects.
Available simulations
Data description
The following data is available from this project :
- simulation snapshot at $Z\simeq 3$
- simulation snapshot at $Z\simeq 2$
- simulation snapshot at $Z\simeq 1$
