Supernova neutrino challenges Christian Y. Cardall Oak Ridge National Laboratory Physics Division...

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Supernova neutrino challengesSupernova neutrino challenges

Christian Y. Cardall

Oak Ridge National LaboratoryPhysics Division

University of Tennessee, KnoxvilleDepartment of Physics and Astronomy

Terascale Supernova Initiativehttp://www.phy.utk.edu/tsi

Supernova neutrino challengesChristian Y. CardallNOW2004, Conca Specchiulla, Italy, 11-17 September 2004

Introduction to supernovaeIntroduction to supernovae

Peter Apian, Cosmographia (1524)

Tycho Brahe, De Nova et Aevi Memoria Prius Visa Stella (1573)

Johannes Kepler, De Stella Nova in Pede Serpentarii, (1606)

M31 (Andromeda Galaxy)

SN 1987A

Tarantula Nebula

SN 1998aq(in NGC 3982)

The name "supernova" dates from the 1930s.New stars or "novae" were well known.

The debate about the nature of spiral nebulae led to the realization that there must be

"giant novae" (Lundmark 1920),novae of "impossibly great absolute

magnitudes" (Curtis 1921),"exceptional novae" (Hubble 1929)"Hauptnovae" (Baade 1929).

The name "supernova" dates from the 1930s.The word "supernova" is claimed to have been

used by Baade and Zwicky since 1931.

LSN/LCN=103

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)

Physical classification of supernovae:Thermonuclear runaway;

Type Ia, accretion onto a white dwarf.

Physical classification of supernovae:Core collapse of a massive star;

Type II, outer H layer remains at collapse;

Type Ib, outer H layer stripped before collapse;

Type Ic, outer H and He layers stripped before collapse.

Neutrino predictions ca. 1986Energy release ~ 1053 erg in neutrinos,Emitted on a time scale of seconds,With an average neutrino energy of ~10 MeV

Burrows and Lattimer 1986

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

On the way to explosion…Accretion continues until stalled shock is

reinvigorated: relation between neutron star mass and delay to explosion

Optical display is powered by the decay of 56Ni; connection to neutrino transport

The electron fraction…

which determines how much 56Ni is produced is set by neutrino interactions:

Dispersion of elements, electromagnetic display

Chandra X-ray Observatory (1999)

Chandra X-ray Observatory (2004)

Survey of collapse Survey of collapse simulationssimulations

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...

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.

Simulations of collapse and explosionSpherical symmetry + mixing prescription,

simplified neutrino transport

Totani, Sato, Dalhed, & Wilson (1998)

1.5 2M

S 3S 1M

N GR N GR N GR N GR N GR N GR N GR N GR

sNeutrino radiation transport

Fluid mixing prescription in the coreboosts neutrino luminosities; notaccepted by most other investigators

Simulations of collapse and explosionMultiple spatial dimensions, simplified neutrino

transport

Fryer & Warren (2002) Burrows, Hayes, & Fryxell (1995)

1.5 2M

S 3S 1M

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

56Ni mass too small; Ye too low.

Simulations of collapse and explosionMultiple spatial dimensions, simplified neutrino

transport

Janka & Mueller (1996)

Mezzacappa, Calder, Bruenn, Blondin, Guidry, Strayer, & Umar (1998)

1.5 2M

S 3S 1M

Simulations of collapse and explosionSpherical symmetry, sophisticated neutrino

transport

Rampp & Janka (2000)

transport

Thompson, Burrows, & Pinto (2002)

1.5 2M

S 3S 1M

transport

Liebendoerfer, Mezzacappa, Thielemann, Messer, Hix, & Bruenn (2001)

1.5 2M

S 3S 1M

Simulations of collapse and explosionMultiple spatial dimensions, intermediate neutrino

transport

Janka, Buras, & Rampp (2002)

1.5 2M

S 3S 1M

Neutron star mass and 56Ni mass are reasonable.

The Terascale Supernova The Terascale Supernova InitiativeInitiative

A diverse and experienced investigator team...

...with expertise in all necessary areas...Radiation transport,

(Magneto-)hydrodynamics,

Nuclear and weak interaction physics,

Computer science,Large sparse linear systems,

Data management and visualization;

...and support from the U.S. Department of Energy:Funding through the DOE Office of Sciences'

SciDAC program,

Access to DOE's terascale machines (several 1012 bytes of memory and flops),

Access to the expertise of teams specializing inAdvanced solvers,

Advanced computational meshes,

Performance on parallel architectures,

Data management and visualization,

Software interoperability and reusability.

Accretion shock instabilityA standing accretion shock, an analytic solution in

spherical symmetry, is used as an initial condition.

Blondin, Mezzacappa, & DeMarino (2003)

Accretion shock instabilityThe standing accretion shock

is unstable in 2D/3D to thepoint of explosion.

QuickTime™ and aVideo decompressorare needed to see this picture.

Neutrino radiation transport: a computational challenge

Large dynamic range in time and spaceTime scale of neutrino interactions is many

orders of magnitude smaller than the fluid time scale

Use implicit time differencing: Evaluate right-hand side at new values of the variables

Gravitational collapse gives a range of spatial scalesSome features need higher resolution, e.g. shock

Neutrino radiation transport: a computational challenge

Dimensionality

2D: solution vector of several 109 elements3D: solution vector approaching 1012 elements

1.5 2M

S 3S 1M

Adaptive mesh refinement

Supernova neutrino challengesSupernova neutrino challenges

ProgenitorsTheory

Dense matter equation of stateNeutrino interactions with nuclei, dense matterNeutrino transport with flavor mixing, collisions,

time and space dependence

ComputationSpatially multidimensional, energy- and angle-

dependent, implicit neutrino transportInclusion of physics: magnetic fields, general

relativity, nuclear reaction networksObservation (talks by M. Selvi and A. Mirizzi this afternoon)

Large detectorsSignal expectations

Supernova neutrino challenges Christian Y. Cardall Oak Ridge National Laboratory Physics Division...

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