On the interplay between cosmological shock waves and their environment

Abstract

Cosmological shock waves are tracers of the thermal history of the structures in the Universe. They play a crucial role in redistributing the energy within the cosmic structures and are also amongst the main ingredients of galaxy and galaxy cluster formation. Understanding this important function requires a proper description of the interplay between shocks and the different environments where they can be found. In this paper, an Adaptive Mesh Refinement (AMR) Eulerian cosmological simulation is analysed by means of a shock-finding algorithm that allows to generate shock wave maps. Based on the population of dark matter halos and on the distribution of density contrast in the simulation, we classify the shocks in five different environments. These range from galaxy clusters to voids. The shock distribution function and the shocks power spectrum are studied for these environments dynamics. We find that shock waves on different environments undergo different formation and evolution processes, showing as well different characteristics. We identify three different phases of formation, evolution and dissipation of these shock waves, and an intricate migration between distinct environments and scales. Shock waves initially form at external, low density regions and are merged and amplified through the collapse of structures. Shock waves and cosmic structures follow a parallel evolution. Later on, shocks start to detach from them and dissipate. We also find that most of the power that shock waves dissipate is found at scales of k ∼ 0.5 Mpc −1 , with a secondary peak at k ∼ 8 Mpc −1 . The evolution of the shocks power spectrum confirms that shock waves evolution is coupled and conditioned by their environment.

The large-scale environment from cosmological simulations – I. The baryonic cosmic web

“…Both quantities are theoretically connected with radio signals, such as the synchrotron or the H I 21-cm line emission, which raise new possibilities for detecting gas filaments. Interestingly, using a shock-finding algorithm (Planelles & Quilis 2013), Martin-Alvarez et al (2017) studied shocks in different environments and found that shocks in filaments display a spectral slope coincident with the gas matter power spectrum. That implies a consistency distribution of gas in both real and phase spaces.…”

How primordial magnetic fields shrink galaxies

“…Alternatively, galactic magnetic fields might have evolved through in-situ large amplification of weak primordial seeds (Pakmor et al 2014;Vazza et al 2014;Martin-Alvarez et al 2018); or been seeded through processes such as stellar winds, supernovae (SNe), or AGN (Beck et al 2013;Butsky et al 2017;Vazza et al 2017;Katz et al 2019) acting as small-scale batteries. Other possibilities are their generation during reionization (Durrive et al 2017), or their amplification prior to accretion onto galaxies or galaxy clusters by shock-induced turbulence (Kulsrud et al 1997;Ji et al 2016), potentially tracing the spectrum of cosmic shock waves (Martin-Alvarez et al 2017). Amongst these diverse scenarios, the main advantage provided by a primordial origin is a simultaneous explanation of the existence of cosmic, cluster, and galactic magnetic fields.…”

Shocks and Non-thermal Particles in Clusters of Galaxies

“…Sunyaev and Zeldovich, 1972;Markevitch and Vikhlinin, 2007;Bykov et al, 2008a;Kushnir and Waxman, 2009;Brüggen et al, 2012;Cavaliere and Lapi, 2013). Around galaxy clusters, strong M ≥ 10−10 2 accretion shocks should exist in a quasi-stationary way and mark the transition from smooth infalling matter to halos undergoing their virialisation process, as illustrated in the top panels of Fig.1 (Miniati et al, 2000;Ryu et al, 2003b;Pfrommer et al, 2006;Vazza et al, 2009;Planelles and Quilis, 2013;Schaal et al, 2016;Martin-Alvarez et al, 2017). The statistics of shocks in the Universe is predicted to be dominated by structure formation shocks, with only a minor contribution from non-gravitational processes, as shown in the bottom left panel of Fig.1 (e.g.…”