FOREVER22: galaxy formation in protocluster regions

Abstract

We present results from a new cosmological hydrodynamics simulation campaign of protocluster (PC) regions, FOREVER22: FORmation and EVolution of galaxies in Extremely-overdense Regions motivated by SSA22. The simulations cover a wide range of cosmological scales using three different zoom set-ups in a parent volume of (714.2 Mpc) 3 : PCR (Proto-Cluster Region; V = (28.6 Mpc) 3 and SPH particle mass, m SPH = 4.1 × 10 6 M ), BCG (Brightest proto-Cluster Galaxy; V ∼ (3 Mpc) 3 and m SPH = 5.0 × 10 5 M ), and First ( V ∼ (0.4 Mpc) 3 and m SPH = 7.9 × 10 3 M ) runs, that allow to focus on different aspects of galaxy formation. In the PCR runs, we follow 10 PCs, each harbouring 1 -4 SMBHs with M BH 10 9 M . One of the PC cores shows a spatially close arrangement of seven starburst galaxies with SFR 100 M yr −1 each, that are dust-obscured and would appear as submillimeter galaxies with flux 1 mJy at 1.1 mm in observations. The BCG runs show that the total SFRs of haloes hosting BCGs are affected by AGN feedback, but exceed 1000 M yr −1 at z 6. The First runs resolve mini-haloes hosting population (Pop) III stars and we show that, in PC regions, the dominant stellar population changes from Pop III to Pop II at z 20, and the first galaxies with SFR 18 M yr −1 form at z ∼ 10. These can be prime targets for future observations with the James Webb Space Telescope. Our simulations successfully reproduce the global star formation activities in observed PCs and suggest that PCs can kickstart cosmic reionization.

Radiation hydrodynamics simulations of massive star cluster formation in giant molecular clouds

“…The self-shielding of H 2 molecules is more efficient than that of CO molecules. Therefore, the radius of the CO photodissociation region is larger than that of H 2 , and the region between the two photodissociation radii corresponds to the "COdark" molecular cloud (e.g., van Dishoeck & Black 1988;Wolfire et al 2010;Inoguchi et al 2020). Hosokawa & Inutsuka (2006) transport of photodissociation photons to estimate each H 2 line absorption accurately.…”

“…Also, YMCs are likely to form in the early Universe, and some of them remain as globular clusters (GCs) in the present-day galaxies (e.g., Kruijssen 2014). These massive dense clusters can be main formation sites of massive stars which regulate the star formation in galaxies via stellar feedback such as photoionization, stellar wind, and supernovae (e.g., Schaye et al 2010;Wise et al 2012;Hasegawa & Semelin 2013;Yajima et al 2017Yajima et al , 2020. Besides, YMCs are gravitationally bounded and can produce black hole binaries via multi-body gravitational interaction (e.g., Portegies Zwart & McMillan 2000;Fujii et al 2017;Kumamoto et al 2019), likely resulting in gravitational wave events (Abbott et al 2016).…”

Formation of the first galaxies in the aftermath of the first supernovae

“…The code treats the formation/evolution of Pop III stars, LW radiation feedback, SN feedback, non-equilibrium primordial chemistry with equilibrium metal cooling, which are implemented in the First Billion Year (FiBY) project (Johnson et al 2013). Recently the code was updated in regard to the feedback from stars and black holes and the dust destruction in Forever22 project (Yajima et al 2020). Our implementation for the thermal evolution is based on Johnson et al (2013).…”

Far and extreme UV radiation feedback in molecular clouds and its influence on the mass and size of star clusters

“…Massive stars inject momentum and energy into the surrounding medium via radiation, stellar wind, and supernovae (Krumholz et al 2019). These processes regulate star formation and induce galactic wind from galaxies (e.g., Yajima et al 2017Yajima et al , 2020Nelson et al 2019). In a galactic scale, the conversion from gas to stars slowly proceeds.…”