Download - GRB Outflows from Pop III Stars

GRB Outflows from Pop III Stars

Aimee Hungerford, Gabe RockefellerChris Fryer, Patrick Young

Los Alamos National Laboratory

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are needed to see this picture.Motivation

• 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.


are needed to see this picture.Outline

• Hydro Simulations Flows don’t really show a disk Angular momentum transport Outflow trajectories

• Neutrino Emission Average energy and luminosity Ye evolution

• Preliminary Nucleosynthesis


are needed to see this picture.Model

(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


are needed to see this picture.Outflows

Spiral density wave pattern seen face-on.Convective-like flows are evident in edge-on

view…not very “disk-like” at all.


are needed to see this picture.

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.


are needed to see this picture.Outflow Trajectory

Sample trajectories from our 3D collapsar model and a disk wind model (Pruet, Thompson &

Hoffman 2004) for comparison.


are needed to see this picture.Neutrino Fluxes

• Electron fraction is reset by neutrinos, but does not achieve the equilibrium (ye near 0.5) implied by luminosity and mean energy of and .


are needed to see this picture.Nucleosynthesis


are needed to see this picture.Conclusions

• 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.


are needed to see this picture.

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

Download - GRB Outflows from Pop III Stars

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