grb outflows from pop iii stars
DESCRIPTION
GRB Outflows from Pop III Stars. Aimee Hungerford, Gabe Rockefeller Chris Fryer, Patrick Young Los Alamos National Laboratory. Motivation. Collapsar model is the favored mechanism for long duration GRBs Pop III stars naturally satisfy the key ingredients needed for the collapsar model - PowerPoint PPT PresentationTRANSCRIPT
GRB Outflows from Pop III Stars
Aimee Hungerford, Gabe RockefellerChris Fryer, Patrick Young
Los Alamos National Laboratory
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• Collapsar model is the favored mechanism for long duration GRBs
• Pop III stars naturally satisfy the key ingredients needed for the collapsar model Massive star Low Metallicity
• 3D Hydro simulations of these objects can provide insight into the properties of GRB ejecta.
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• Hydro Simulations Flows don’t really show a disk Angular momentum transport Outflow trajectories
• Neutrino Emission Average energy and luminosity Ye evolution
• Preliminary Nucleosynthesis
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(up to t = 5 sec)
• 60 Msun (Hydrogen envelope present)• Zero Metallicity• Fast Rotating (B braking neglected)• Accretion Rate (roughly 0.1 Msuns-1)• MBH = ~2 Msun
boundary at R = 10 km Newtonian gravity
• 11 x 1051 erg explosion
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Spiral density wave pattern seen face-on.Convective-like flows are evident in edge-on
view…not very “disk-like” at all.
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Angular Momentum Transport
Angular momentum is being transported inward (red) and outward (blue) suggesting very different flow dynamics than those in a typical alpha disk model.
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Sample trajectories from our 3D collapsar model and a disk wind model (Pruet, Thompson &
Hoffman 2004) for comparison.
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• Electron fraction is reset by neutrinos, but does not achieve the equilibrium (ye near 0.5) implied by luminosity and mean energy of and .
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• 3D engine structure seems to be more complicated than expected.
• Very energetic explosion is launched (even without a jet component.)
• Electron fraction is uncertain and sets the nucleosynthesis of the outflow material. “classical” r-process synthesis seems
unlikely.
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Collapse - 60 Solar Mass Progenitor
Set-up and Simulation• Zero metallicity star• 2.5 million particles for
inner 5 solar masses• ~100,000-200,000 cpu
hours per run• Note High Angular
Momentum (with respect to the angular momentum of the innermost stable circular orbit) in the first 2 solar masses