Exploding Massive Stars:

The Perfect ‘App’ for Computational Physics

SESAPS 2003

John M. BlondinNorth Carolina State University

What is a supernova?

A single, new star outshines an entire galaxy for weeks.

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The High-Z Supernova Search

The High-Z Supernova Search

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The Crab Supernova Remnant

This debris is located in the same position as a supernova seen by Chinese astronomers in 1054.

Historical Supernovae

Year Report Status 1006 China, Arab lands, Europe Identified with radio SNR 1054 China, Japan Crab Nebula 1181 China, Japan SNR 3C58 1572 Europe (Tycho Brahe), China Tycho's remnant 1604 Europe (Kepler), Japan, Korea Kepler's remnant

Cassiopeia A

OpticalRadio X-Ray

What are we looking at?

•Brightness & distance => 10 billion Suns

•Doppler shifts => expansion at 1000 km/s

•X-Ray emission => few solar masses

An expanding blastwave with 1051 ergs

Where did all that energy come from?

Type Ia - stellar-sized nuclear bomb

Type II - gravitational collapse of a massive star

SN1987A confirmed the basic supernova theory

•A star disappeared! Supernovae do result from the death of a massive star.

•Neutrinos were detected (2002 Nobel Prize), confirming formation of neutron star in the core.

What is left to learn?

• How do they explode?!

• What is the neutrino signature?

• Do they produce gravitational waves?

A Brief History of Supernova Theory

• 1957 Burbidge, Burbidge, Fowler, and Hoyle

• 1966 Colgate and White

• 1985 Bethe and Wilson

• 1992 Herant, Benz, and Colgate

Thermonuclear runaway in envelope

Neutrino-Driven prompt explosion

Shock reheating via neutrino energy deposition

Convective instability above neutrino-sphere

Need Boltzmann SolutionNeed Angular DistributionNeed SpectrumNeed Neutrino Distribution

Fluid Instabilities Rotation Magnetic Fields

6D RMHD Problem!6D RMHD Problem!Need these to few percent accuracy!

http://www.phy.ornl.gov/tsi/TeraScale Supernova InitiativeTeraScale Supernova Initiative

10 Institution, 17 Investigator, ~ 40 Person, Interdisciplinary Effort ascertain the core collapse supernova mechanism(s)understand supernova phenomenology

e.g.: (1) element synthesis, (2) neutrino, gravitational wave, and gamma ray signatures provide theoretical foundation in support of OS experimental facilities (RHIC, SNO, RIA, NUSL)develop enabling technologies of relevance to many applications

e.g. 3D, multifrequency, precision radiation transportserve as testbed for development and integration of technologies in simulation “pipeline”

e.g. data management, networking, data analysis, and visualization

Explosions ofExplosions ofMassive StarsMassive Stars Relevance:Relevance:

Element ProductionElement ProductionCosmic LaboratoriesCosmic LaboratoriesDriving ApplicationDriving Application

With ISIC and other collaborators:With ISIC and other collaborators:~120 people from 24 institutions involved.~120 people from 24 institutions involved.

What will it take? Tera/Peta-Scale 3D, General Relativistic, Radiation Magnetohydrodynamics State of the Art Nuclear and Weak Interaction Physics

“Infrastructure” Needs: Applied Mathematics Tera- and Peta-Scale Sparse Linear Systems of Equations

“Infrastructure” Needs: Data Management/Visualization 1-10 Tb/Variable/Simulation!

Manage? Analyze? Render?

“Infrastructure” Needs: NetworkingHow can a nationally distributed team work together effectively?

Messer et al. (2002) Liebendoerfer et al. (2002)

No Explosions!No Explosions!New Microphysics?New Microphysics?

High-Density Stellar Core ThermodynamicsHigh-Density Stellar Core ThermodynamicsNeutrino-Matter InteractionsNeutrino-Matter Interactions

New Macrophysics? (2D/3D Models)New Macrophysics? (2D/3D Models)Fluid Instabilities, Rotation, Magnetic FieldsFluid Instabilities, Rotation, Magnetic Fields

TSI will explore both!

No 2D/3D supernova models with realistic neutrino transport exist!

One Dimension is Too Simple

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SAS Solution is Stable in One Dimension

time

radius

Pressure perturbation

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SASI: l=1 mode is overstable

The obliquity of the accretion shock deflects the radial in-flow

Spherical shock

Radial in-fall

Shocknormal

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Challenges in Data Management

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First steps toward understanding the role of magnetic fields…

What impact will they have on the collapse and postbounce dynamics?How much do they factor into generating the explosion?

How much will they be amplified, and how? Wrapping Dynamo Magnetorotational Instability (Balbus and Hawley 1991)

Akiyama et al. (2002)

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Asif ud-Doula (see poster)SASI + Dipole Field

How did this happen?!