Large-Scale Structure Formation: From the First Non-linear Objects to Massive Galaxy Clusters

Abstract

The large-scale structure of the Universe formed from initially small perturbations in the cosmic density field, leading to galaxy clusters with up to 10 15 M at the present day. Here, we review the formation of structures in the Universe, considering the first primordial galaxies and the most massive galaxy clusters as extreme cases of structure formation where fundamental processes such as gravity, turbulence, cooling and feedback are particularly relevant. The first non-linear objects in the Universe formed in dark matter halos with 10 5 − 10 8 M at redshifts 10 − 30, leading to the first stars and massive black holes. At later stages, larger scales became non-linear, leading to the formation of galaxy clusters, the most massive objects in the Universe. We describe here their formation via gravitational processes, including the self-similar scaling relations, as well as the observed deviations from such self-similarity and the related non-gravitational physics (cooling, stellar feedback, AGN). While on intermediate cluster scales the self-similar model is in good agreement with the observations, deviations from such self-similarity are apparent in the core regions, where numerical simulations do not reproduce the current observational results. The latter indicates that the interaction of different feedback processes may not be correctly accounted for in current simulations. Both in the most massive clusters of galaxies as well as during the formation of the first objects in the Universe, turbulent structures and shock waves appear to be common, suggesting them to be ubiquitous in the non-linear regime.

The FABLE simulations: a feedback model for galaxies, groups, and clusters

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MUSE tells the story of NGC 4371: The dawning of secular evolution

“…Martig et al 2009), in dense galaxy environments, such as galaxy clusters, the removal of cold gas from galaxies and their surroundings is expected to be efficient in quenching star formation (see Balogh et al 2004). The formation of galaxy clusters is a long process that has initial phases at redshifts higher than about 3, and although massive clusters have been observed at redshifts about unity or more (Brodwin et al 2010(Brodwin et al , 2013Propris et al 2015;Ma et al 2015), it is expected that cluster formation is a process that goes on well below z ≈ 1 (Kravtsov & Borgani 2012;Planelles et al 2014). In fact, the nearby Virgo cluster is known for not yet being dynamically fully relaxed (Binggeli 1999).…”

The Galaxy Cluster Mass Scale and Its Impact on Cosmological Constraints from the Cluster Population

“…Cosmological simulations have been a workhorse for making predictions for the structure and shape of dark matter haloes for more than twenty years (see e.g. Kravtsov & Borgani 2012;Planelles et al 2015, for reviews). Moreover, the abundance and clustering properties of dark matter haloes that form in the concordance cold dark matter (CDM) models are the standard against which observations are compared in order to derive cosmological constraints.…”