The role of gas and dark matter in the dissociative collision of galaxy cluster Abell 2034 Micheli Trindade Moura, Rubens E. G. Machado Universidade Tecnol´ogica Federal do Paran´a (UTFPR), Curitiba, Brazil  micheli trindade.moura@hotmail.com Galaxy Cluster Formation (GCF) 2021 Abstract: Collisions between galaxy clusters are a frequent sce- nario in the hierarchical model of structures. Dissociative collisions provide an extreme environment of interaction between clusters of galaxies, where the properties of dark matter (DM) in relation to baryonic matter become evident. Investigating dissociative scenar- ios allows a deeper understanding of the behavior and dynamics of baryonic and non-baryonic matter in this context of collision. Abell 2034 (z = 0.114) is a bimodal system composed of a north and a south substructure, it has dissociative features observed in X- rays and gravitational lensing. Using N-body hydrodynamic sim- ulations, we present a theoretical study based on the dissociative collision of A2034, aiming to explore the eﬀect that diﬀerent rela- tive concentrations between the clusters generate on the dynamics of the system. We investigated the relationship of the central density ratios with diﬀerent levels of dissociation, where we analyzed nine models with diﬀerent concentrations of the two components: intra- cluster gas and DM halo for each substructure. We found diﬀerent degrees of dissociation that were quantiﬁed by the relative distance between the X-ray emission peak and the dark matter peaks. We found that the ratio of the gas central densities is more decisive than the ratio of dark matter central densities, in determining the level of dissociation for the parameters of this collision. 1 Introduction Dissociative systems are a peculiarity of collisions between galaxy clusters, and are known in the literature since 2006 with the Bullet Cluster (Clowe et al., 2006). Abell 2034 (A2034) is a cluster at lo- cal Universe (z = 0.114) that has dissociative features. The A2034 is composed of two substructures: A2034N and A2034S. The main points about recent developments of the A2034 in the literature are: • The distance between the X-ray emission peak and the south dark matter peak is around 348 kpc, where the distance between both total mass peaks is ∼720 kpc (Monteiro-Oliveira et al., 2018). Implying in a clearly dissociative system, with gas approximately in the middle of two DM peaks. • This merger system has been observed by X-ray satellites since ROSAT (David et al., 1999), and more recently by XMM- Newton (Okabe & Umetsu, 2008) and Chandra (Kempner et al., 2003; Owers et al., 2014). • More recently mass reconstruction are performed by weak gravita- tional lensing method in 2018 by Monteiro-Oliveira et al. (2018). Numerical simulations were developed motivated by the analysis of X-rays and gravitational lensing, leading to a proposed scenario for this collision, where we observed the system at 0.26 Gyr after the central passage (Moura et al., 2021). From this numerical scenario, we carry out a theoretical exploration of the eﬀect that diﬀerent gas and DM concentrations cause in the dissociation of the A2034 merger system. Figure 1. Gas scale length variations, for north (200, 300 and 400 kpc) and south (300, 400 and 500 kpc) substructures. The ﬁrst row shows gas density maps with contours representing total mass. The second row shows projected temperature maps for each model. The third row shows X-rays mocks from counts/pixel and contour curves of the total mass. 2 Simulation setup We aim to investigate the dissociative collision of Abell 2034 using N-body hydrodynamic simulations. To simulate this merger con- text, we set up two spherical galaxy clusters. The code employed and details about the simulation are: • We adopt the Gadget-2 code (Springel, 2005), which uses smoothed particle hydrodynamic (SPH); • The initial conditions are composed of 106 gas particles and 106 DM particles for each cluster; • The