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Exploding Massive Stars:
The Perfect ‘App’ for Computational Physics
John M. Blondin
North Carolina State University
SESAPS
2003
What is a supernova?
A single, new star outshines
an entire galaxy for weeks.
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The High-Z Supernova Search
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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
Radio
Optical
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
Thermonuclear runaway in envelope
• 1966 Colgate and White
Neutrino-Driven prompt explosion
• 1985 Bethe and Wilson
Shock reheating via neutrino energy deposition
• 1992 Herant, Benz, and Colgate
Convective instability above neutrino-sphere
Need Boltzmann Solution
Need Angular Distribution
Need Spectrum
Need Neutrino Distribution
 Fluid Instabilities
 Rotation
 Magnetic Fields
Need these to few percent accuracy!
6D RMHD Problem!
TeraScale Supernova Initiative
http://www.phy.ornl.gov/tsi/
Explosions of
Massive Stars
Relevance:
Element Production
Cosmic Laboratories
Driving Application
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 transport
serve as testbed for development and integration of technologies in simulation “pipeline”
e.g. data management, networking, data analysis, and visualization
With ISIC and other collaborators:
~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: Networking
How can a nationally distributed team work together effectively?
Messer et al. (2002)
Liebendoerfer et al. (2002)
No Explosions!
New Microphysics?
High-Density Stellar Core Thermodynamics
TSI will explore both!
Neutrino-Matter Interactions
New Macrophysics? (2D/3D Models)
Fluid Instabilities, Rotation, Magnetic Fields
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
Pressure perturbation
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radius
time
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SASI: l=1 mode is overstable
Spherical shock
Shock
normal
Radial in-fall
The obliquity of the accretion shock deflects the radial in-flow
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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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SASI + Dipole Field
Asif ud-Doula (see poster)
How did this happen?!