supernova neutrinos

Supernova NeutrinosSupernova Neutrinos

Christian Y. Cardall

Oak Ridge National LaboratoryPhysics Division

University of Tennessee, KnoxvilleDepartment of Physics and Astronomy

Supernova NeutrinosChristian Y. CardallNOW 2006, Conca Specchiulla, Italy, 9-16 September 2006

Core-collapse supernovae Core-collapse supernovae

Survey of collapse simulationsSurvey of collapse simulations

Supernova neutrino signalsSupernova neutrino signals

New effects at small New effects at small ∆m∆m22??


SN 1998aq(in NGC 3982)


Spectral classification of supernovae:

Filippenko (1997)

Type II(obvious H)

Type I(no H)

Type Ia(no H, strong Si)

Type Ic(no H, He, Si)

Type Ib(no H, obvious He)


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.


The observables to understand includeExplosion (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-ray;images, light curves, spectra, polarimetry...


Survey of collapse simulations Survey of collapse simulations


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

Mag

neto

hydr

odyn

amic

sNeutrino radiation transport


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 fraction…

is set by neutrino interactions:


Fluid dynamics: 2D, 3D

Neutrino transport: 2D + 0D, 3D + 0D

Fryer & Warren (2002)Mezzacappa et al. (1998)

Fluid dynamics: 2D

Neutrino transport: 1D + 1D


2S 0M

1S 1M

3S 0M

1S 2M

2S 1M

1.5 2M

S 3S 1M

2S 3M


1S N

GR

2S N

B

GR

B

3S N

B

GR

B

Mag

neto

hydr

odyn

amic


Neutron star mass too small; heating drives explosion too soon.

N=50 overproduction; Ye too low.


Fluid dynamics: 1D


Liebendörfer et al. (2001, 2004)

Rampp & Janka (2000, 2002)

Thompson, Burrows, & Pinto (2002)

Kitaura, Janka, & Hillebrandt (2006)


2S 0M

1S 1M

3S 0M

1S 2M

2S 1M

1.5 2M

S 3S 1M

2S 3M


1S N

GR

2S N

B

GR

B

3S N

B

GR

B

Mag

neto

hydr

odyn

amic


Explosion only for 8-10 M stars with O-Ne-Mg cores.

Reasonable neutron star mass; accretion continues during delay.

Reasonable N=50 element production expected; ejected matter has Ye > 0.46.

May explain some subluminous Type II-P.


Fluid dynamics: 2D


Burrows et al. (2006)

Swesty & Myra (2005)


2S 0M

1S 1M

3S 0M

1S 2M

2S 1M

1.5 2M

S 3S 1M

2S 3M


1S N

GR

2S N

B

GR

B

3S N

B

GR

B

Mag

neto

hydr

odyn

amic


Explosion for 11, 15, 25 M progenitors.

Some neutrino transport details left out; is the acoustic mechanism physical?


Not yet clear if Ye gives reasonable nucleosynthesis or if the model is resolved.


Fluid dynamics: 2D

Neutrino transport: 1.5D + 2D

Buras et al. (2006)


2S 0M

1S 1M

3S 0M

1S 2M

2S 1M

1.5 2M

S 3S 1M

2S 3M


1S N

GR

2S N

B

GR

B

3S N

B

GR

B

Mag

neto

hydr

odyn

amic


Full 180º allows an 11 M star to explode; what about higher mass progenitors?


Reasonable N=50 element production expected; some of ejecta has Ye > 0.5.

Acoustic mechanism not yet probed.


2S 0M

1S 1M

3S 0M

1S 2M

2S 1M

1.5 2M

S 3S 1M

2S 3M


1S N

GR

2S N

B

GR

B

3S N

B

GR

B

Mag

neto

hydr

odyn

amic



Supernova neutrino signals Supernova neutrino signals


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,



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.



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.



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:



~ 1s hydrodynamic simulations with decent neutrino transport (Wilson 1984)


Burrows and Lattimer 1986


~ 20s ‘stellar evolution’ with crude transport


SN 1987A

Tarantula Nebula


The lucky messengers…

Each “event” involves ~109 “messengers,”with at most 1 “detected”

SN1987A sent ~1058 “messengers,”with ~two dozen detected

Raffelt (1999)


Prediction vs. observationBurrows and Lattimer (1987)


A neutrino window into the supernova…L

iebendörfer et al. (2004)

Buras et al. (2005)


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

Thompson et al. (2005)Sumiyoshi et al. (2006)

Pons et al. (2001)


Neutrino mixing unknowns: 13 and hierarchyR

affelt (2005)


Duan et al. (2006)



Survey of collapse simulationsSurvey of collapse simulations

Supernova neutrino signalsSupernova neutrino signals


supernova neutrinos

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