Supernova Neutrinos

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Supernova Neutrinos
Christian Y. Cardall Oak Ridge National
Laboratory Physics Division University of
Tennessee, Knoxville Department of Physics and
Astronomy
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Core-collapse supernovae Survey of collapse
simulationsSupernova neutrino signalsNew
effects at small ?m2?
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Core-collapse supernovae
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SN 1998aq (in NGC 3982)
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• Spectral classification of supernovae

Filippenko (1997)
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Rotation
Magnetic Fields
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• Some key ingredients are
• Neutrino transport/interactions,
• Spatial dimensionality
• Dependence on energy and angles
• Relativity
• Comprehensiveness of interactions
• (Magneto)Hydrodynamics/gravitation,
• Dimensionality
• Relativity
• Equation of state/composition,
• Dense matter treatments
• Number and evolution of nuclear species
• Diagnostics,
• Accounting of lepton number
• Accounting of energy
• Accounting of momentum.

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• The observables to understand include
• Explosion (and energy thereof)
• Neutrinos
• Remnant properties,
• Mass, spin, kick velocity, magnetic fields
• Gravitational waves
• Element abundances
• Measurements across the EM spectrum,
• IR, optical, UV, X-ray, gamma-rayimages, light
  curves, spectra, polarimetry...

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Survey of collapse simulations
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Neutrino radiation transport
2S 0M 1S 1M 3S 0M 1S 2M 2S 1M 1.5 2M S 3S 1M 2S 3M
N GR N GR N GR N GR N GR N GR N GR N GR
1S N
GR
2S N
B
GR
B
3S N
B
GR
B
Magnetohydrodynamics
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• Two observables beyond explosion
• Accretion continues until the stalled shock is
  reinvigorated relation between neutron star mass
  and delay to explosion
• The abundance of nuclei with a closed shell of 50
  neutrons
• The electron fractionis set by neutrino
  interactions

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• Fluid dynamics 2D, 3D
• Neutrino transport 2D 0D, 3D 0D

Fluid dynamics 2D Neutrino transport 1D 1D
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Neutrino radiation transport
2S 0M 1S 1M 3S 0M 1S 2M 2S 1M 1.5 2M S 3S 1M 2S 3M
N GR N GR N GR N GR N GR N GR N GR N GR
1S N
GR
2S N
B
GR
B
3S N
B
GR
B
Magnetohydrodynamics
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Fluid dynamics 1D Neutrino transport 1D 2D
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Neutrino radiation transport
2S 0M 1S 1M 3S 0M 1S 2M 2S 1M 1.5 2M S 3S 1M 2S 3M
N GR N GR N GR N GR N GR N GR N GR N GR
1S N
GR
2S N
B
GR
B
3S N
B
GR
B
Magnetohydrodynamics
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Fluid dynamics 2D Neutrino transport 2D 1D
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Neutrino radiation transport
2S 0M 1S 1M 3S 0M 1S 2M 2S 1M 1.5 2M S 3S 1M 2S 3M
N GR N GR N GR N GR N GR N GR N GR N GR
1S N
GR
2S N
B
GR
B
3S N
B
GR
B
Magnetohydrodynamics
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Fluid dynamics 2D Neutrino transport 1.5D
2D
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Neutrino radiation transport
2S 0M 1S 1M 3S 0M 1S 2M 2S 1M 1.5 2M S 3S 1M 2S 3M
N GR N GR N GR N GR N GR N GR N GR N GR
1S N
GR
2S N
B
GR
B
3S N
B
GR
B
Magnetohydrodynamics
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Neutrino radiation transport
2S 0M 1S 1M 3S 0M 1S 2M 2S 1M 1.5 2M S 3S 1M 2S 3M
N GR N GR N GR N GR N GR N GR N GR N GR
1S N
GR
2S N
B
GR
B
3S N
B
GR
B
Magnetohydrodynamics
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Supernova neutrino signals
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• Neutrino predictions ca. 1987
• Did anyone do gravitational collapse as a Fermi
  problem?
• Assume the stellar core is basically a white
  dwarf a Chandrasekhar mass of 1.4 M? and about
  104 km.
• Assume that the neutron star it collapses to is
  essentially a giant nucleus, and hence has
  density n 0.16 fm-3.
• From the mass and final density,

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• Neutrino predictions ca. 1987
• How long will it take to collapse? The free-fall
  time scale is
• The iron core is roughly half protons before
  collapse. Electron capture converts each proton
  to a neutron with the emission of an
  antineutrino.
• Assume the neutrinos are trapped (check the
  consistency of this later). Then the number
  density of antineutrinos is half the final
  nucleon density.

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• Neutrino predictions ca. 1987
• From the number density of antineutrinos, find
  their typical energy from the inter-particle
  spacing
• On what timescale will the neutrinos diffuse out?
• This validates the assumption of neutrino
  trapping.

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• Neutrino predictions ca. 1987
• Almost forgot the gravitational binding energy
  released during collapse will be released in
  neutrinos.
• If neutrinos are trapped we expect all flavors to
  be produced. They will be emitted with a
  hierarchy of energies because differences in
  their interactions cause them to decouple at
  different radii

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Neutrino predictions ca. 1987 1s hydrodynamic
simulations with decent neutrino transport
(Wilson 1984)
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Neutrino predictions ca. 1987 20s stellar
evolution with crude transport
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SN 1987A
Tarantula Nebula
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• The lucky messengers

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• Prediction vs. observation

Burrows and Lattimer (1987)
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• A neutrino window into the supernova

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• could provide information about, for instance,
  rotation and the nuclear equation of state.

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• Neutrino mixing unknowns ?13 and hierarchy

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New effects at small ?m2?
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(No Transcript)
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Duan et al. (2006)
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Core-collapse supernovae Survey of collapse
simulationsSupernova neutrino signalsNew
effects at small ?m2?