White Dwarf Mergers as Supernova Progenitors Max Katz Blue Waters - - PowerPoint PPT Presentation

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Nov 10, 2022 609 likes •798 views

White Dwarf Mergers as Supernova Progenitors Max Katz Blue Waters Symposium May 13, 2015 Collaborators: Mike Zingale, Alan Calder, Doug Swesty (SBU) Ann Almgren, Weiqun Zhang (LBL) PRAC PI: Stan Woosley (UCSC) Max Katz White Dwarf Mergers as

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White Dwarf Mergers as Supernova Progenitors

Max Katz Blue Waters Symposium May 13, 2015 Collaborators: Mike Zingale, Alan Calder, Doug Swesty (SBU) Ann Almgren, Weiqun Zhang (LBL) PRAC PI: Stan Woosley (UCSC)

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Beacons in the cosmic dark

Brilliant bursts of light that can outshine galaxies Nearly uniform brightness Dark energy discovery (1998) due to Type Ia supernovae Caused by explosions of white dwarfs, but how?

Credit: Chandra Credit: Science@Berkeley Lab

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Mergers of white dwarfs

Credit: NASA / CXC / A. Hobart

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Simulating mergers of white dwarfs

Install equilibrium stellar model

n three-dimensional grid or

particles Apply damping to simulate gravitational radiation See if it gets hot enough to cause a nuclear detonation If so, does the explosion look like what we see?

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CASTRO

Euler equations for compressible hydrodynamics Self-gravity and realistic equation of state Nuclear reaction network and radiation transport included BoxLib framework for adaptive mesh refinement with subcycling in time Hybrid parallelism: MPI between grids, OpenMP within grids Freely available online

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Using CASTRO for mergers

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Changes we’ve made to the code

Gravity, especially boundary conditions and energy coupling Hydrodynamics, especially the core piecewise-parabolic method Equation of state (including work in progress on GPUs)

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Hydro test: gravitational free fall

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Kelvin-Helmholtz Instability and Galilean Invariance

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Credit: xkcd

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Unequal Mass Binary: Inertial Frame

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Unequal Mass Binary: Rotating Frame

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Energy and angular momentum conservation

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Collision

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Weak scaling on Blue Waters

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Strong scaling on Blue Waters

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Download our codes!

github.com/BoxLib-Codes

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Summary

We are using the compressible hydro code CASTRO to simulate the mergers of WDs Our goal is to determine whether the conditions for a detonation form robustly We have made good progress on the verification front and have made numerous updates to the algorithms (Zingale & Katz 2015, ApJ; Katz et al. 2015 in prep)

This work was supported by NSF award AST-1211563. I have used NCSA/Blue Waters, OLCF/Titan, and NICS/Kraken in the course of this research.

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