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Tracing the Halo – Cosmic Web Connection Marius Cautun Kapteyn Astronomical Institute Rien van de Weygaert, Wojciech Hellwing, Carlos Frenk, Bernard J. T. Jones September 6th 2012 CosmoComp 2012, Trieste Introduction Sloan Digital Sky Survey galaxies Outline I - The NEXUS+ algorithm Outline I - The NEXUS+ algorithm II – Halos and the Cosmic Web I – The NEXUS+ Algorithm Challenges: • Multiscale distribution • No clear defined boundaries • Orders of magnitude variation in the density field I – The NEXUS+ Algorithm The NEXUS+ algorithm 1. Apply a filter to the input field. filter I – The NEXUS+ Algorithm The NEXUS+ algorithm 1. Apply a filter to the input field. I – The NEXUS+ Algorithm The NEXUS+ algorithm 1. Apply a filter to the input field. 2. Compute the Hessian of the filtered field f. 2 f (x) H ij ( x ) has eigenvalues: 1 2 3 xi x j I – The NEXUS+ Algorithm The NEXUS+ algorithm 1. Apply a filter to the input field. 2. Compute the Hessian of the filtered field f. 3. Use the Hessian eigenvalues to assign an environment signature to each point. I – The NEXUS+ Algorithm The NEXUS+ algorithm 1. Apply a filter to the input field. 2. Compute the Hessian of the filtered field f. 3. Use the Hessian eigenvalues to assign an environment signature to each point. I – The NEXUS+ Algorithm The NEXUS+ algorithm 1. Apply a filter to the input field. 2. Compute the Hessian of the filtered field f. 3. Use the Hessian eigenvalues to assign an environment signature to each point. 4. Repeat steps 1-3 for a range of filter scales. increasing filter size I – The NEXUS+ Algorithm The NEXUS+ algorithm 1. Apply a filter to the input field. 2. Compute the Hessian of the filtered field f. 3. Use the Hessian eigenvalues to assign an environment signature to each point. 4. Repeat steps 1-3 for a range of filter scales. 5. Combine the environmental signatures of each scale to get a scale independent result. I – The NEXUS+ Algorithm The NEXUS+ algorithm 1. Apply a filter to the input field. 2. Compute the Hessian of the filtered field f. 3. Use the Hessian eigenvalues to assign an environment signature to each point. 4. Repeat steps 1-3 for a range of filter scales. 5. Combine the environmental signatures of each scale to get a scale independent result. 6. Use physical criteria to identify the valid clusters, filaments and walls. I – The NEXUS+ Algorithm NEXUS+ results I – The NEXUS+ Algorithm Cosmic Web evolution 3 20 20 2 (Mpc h1 )volume rendering. Using the data from CosmoGrid simulation (Ishiyama+ 2011). II – Halos and the Cosmic Web Halos and environments Halo fraction Halo mass function II – Halos and the Cosmic Web Halos and environments Angular momentum direction Major axis of halo shape Aragon-Calvo+ (2007), Hahn+ (2007), Codis+ (2012), Trowland+ (2012) II – Halos and the Cosmic Web Environment characteristics II – Halos and the Cosmic Web Environment characteristics Filament diameter II – Halos and the Cosmic Web Environment characteristics Filament diameter Filament linear density II – Halos and the Cosmic Web Halo angular momentum vs. environment Dependence on filamentary density II – Halos and the Cosmic Web Closer to home: Milky Way Wang, Frenk, Navarro, Gao and Sawala (2012): • 3 MW satellites with maximum velocity > 30 km/s 40% for a MW mass 1012 M 0 5% for a MW mass 2·1012 M 0 II – Halos and the Cosmic Web Closer to home: Milky Way Wang, Frenk, Navarro, Gao and Sawala (2012): • 3 Milky Way (MW) satellites with maximum velocity > 30 km/s 40% for a MW mass 1012 M 0 5% for a MW mass 2·1012 M 0 II – Halos and the Cosmic Web Substructure and environment MW resides in a wall-like environment (Tully+ 2008) For MW-like halos in the Millennium 2 simulation: 90% in filaments 10% in walls II – Halos and the Cosmic Web Substructure and environment Number of subhalos with maximum velocity larger than 30km/s for a MW-like halo with 200km/s. 7% of halos in filaments 14% of halos in walls II – Halos and the Cosmic Web Conclusions • The NEXUS+ algorithm: a tool for multiscale and automatic Cosmic Web environment detection. • Very successful in following the evolution of the cosmic environments. • Ideal tool for measuring the influence of the Cosmic Web on dark matter halos and galaxies. • Understanding how the Cosmic Web influences the formation and evolution of halos and galaxies. II – Halos and the Cosmic Web