Cosmological Shocks in Adaptive Mesh Refinement Simulations and the Acceleration of Cosmic Rays

By Samuel W. Skillman, Brian W. O'Shea, E. Hallman, J. Burns, M. Norman. 2008

148 citations recorded by the source corpus.

We present new results characterizing cosmological shocks within adaptive mesh refinement N-body/hydrodynamic simulations that are used to predict nonthermal components of large-scale structure. This represents the first study of shocks using adaptive mesh refinement. We propose a modified algorithm for finding shocks from those used on unigrid simulations that reduces the shock frequency of low Mach number shocks by a factor of ~3. We then apply our new technique to a large, (512 h−1 Mpc)3, cosmological volume and study the shock Mach number (ℳ) distribution as a function of preshock temperature, density, and redshift. Because of the large volume of the simulation, we have superb statistics that result from having thousands of galaxy clusters. We find that the Mach number evolution can be interpreted as a method to visualize large-scale structure formation. Shocks with ℳ < 5 typically trace mergers and complex flows, while 5 < ℳ < 20 and ℳ > 20 generally follow accretion onto filaments and galaxy clusters, respectively. By applying results from nonlinear diffusive shock acceleration models using the first-order Fermi process, we calculate the amount of kinetic energy that is converted into cosmic-ray protons. The acceleration of cosmic-ray protons is large enough that in order to use galaxy clusters as cosmological probes, the dynamic response of the gas to the cosmic rays must be included in future numerical simulations.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/0b3132c2ece533e87655bb2e9eadea541f72db6f

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Citations in the corpus

ENZO: AN ADAPTIVE MESH REFINEMENT CODE FOR ASTROPHYSICS (2013, methodology): “The primary method used in Enzo is the dimensionally unsplit temperature jump method described in detail in Skillman et al. (2008).”
SEARCH FOR COSMIC-RAY-INDUCED GAMMA-RAY EMISSION IN GALAXY CLUSTERS (2013, background): “The intracluster medium (ICM) consists of a hot (1-10 keV) plasma, which has primarily been heated through collisionless shocks that form as a result of the hierarchical build up of galaxy clusters (e.g., Ryu et al. 2003; Pfrommer et al. 2006; Skillman et al. 2008; Vazza et al. 2009).”
Formation of Galaxy Clusters (2012, background): “The right panel of Figure 9 shows the distribution of the kinetic nergy processed by shocks, as a function of the local shock Mach number, for different redshifts (Skillman et al. 2008).”
Shock waves in Eulerian cosmological simulations: main properties and acceleration of cosmic rays (2008, methodology): “…at shocks (Hallman et al. 2003; Keshet et al. 2003; Ryu et al. 2003; Pfrommer et al. 2006).1 Ryu et al. and 1 After this paper was submitted, also Skillman et al. (2008) provided results on shock waves in ENZO AMR simulations, which are broadly consistent with the above works in the literature.”
Acceleration of primary and secondary particles in galaxy clusters by compressible MHD turbulence: from radio haloes to gamma-rays (2010, background): “…and Starburst galaxies (e.g., Völk & Atoyan 1999) and shock waves (e.g., Ensslin et al 1998; Sarazin 1999; Ryu et al 2003; Pfrommer et al. 2006; Skillman et al 2008; Vazza et al 2009b), evidence for the latter process come from the observations of radio relics that indeed suggest a connection…”
DIFFUSIVE SHOCK ACCELERATION SIMULATIONS OF RADIO RELICS (2012, background): “…in filaments and outside cluster virial radii, shocks produced by mergers and flow motions in hotter ICMs are relatively weak with Mach number M . a few (Ryu et al. 2003; Pfrommer et al. 2006; Kang et al. 2007; Skillman et al. 2008; Hoeft et al. 2008; Vazza et al. 2009; Brüggen et al. 2011).”
ON THE CLUSTER PHYSICS OF SUNYAEV–ZEL'DOVICH AND X-RAY SURVEYS. I. THE INFLUENCE OF FEEDBACK, NON-THERMAL PRESSURE, AND CLUSTER SHAPES ON Y–M SCALING RELATIONS (2011, methodology): “…shocks are typically forming at radii> R200 as suggested by numerical simulations (Miniati et al. 2000; Ryu et al. 2003; Pfrommer et al. 2006b; Skillman et al. 2008; Vazza et al. 2009) or indirectly by the action of shock waves on radio plasma bubbles, which represents a novel method of…”
Turbulent Motions and Shocks Waves in Galaxy Clusters simulated with AMR (2009, methodology): “…of the various re-simulations show relevant differences only for shocks withM > 10, where two clear trends can be found: 1 We notice that recently Skillman et al.(2008) pointed out that t e measure of Mach numbers with a temperature-based method using a coordinate split algorithm, overproduces…”
EMU: Evolutionary Map of the Universe (2011, background): “…emission due to WHIM shocks is highly correlated with large-scale structure (LSS) on ,1–4 Mpc scales (Pfrommer et al. 2007; Ryu et al. 2008; Skillman et al. 2008, 2010), and can thus be detected below the EMU noise limits through LSS cross-correlation (Brown et al. 2010) using the…”