Neutrinos in and from Core-Collapse Supernova Explosion

Bernhard Müller(Monash University)

F. Hanke, L. Hüdepohl, H.-Th. Janka, A. Marek(Max-Planck-Institut für Astrophysik, Garching)

I. Tamborra (U Amsterdam), G. Raffelt (MPI for Physics)

Part I: Can we understand neutrino emission in supernova within an error margin of ~5%? Is it

necessary?

Structure of the Proto-Neutron Star and its Environment

“radiative equlibrium”

prot

o-ne

utro

n

star

cor

e

mantle

gain region

cooling region

PNS convection

radiation pressure (,e+,e-)

baryon-dominated, modified by interaction effects & electron

degeneracy

baryon pressure (ideal gas, non-degenerate)

nuclear forces dominate

EoS

CC (absorption)

CC & NC, modified by in-medium effects

CC & NC

CC & NC, modified by in-medium effects

Little interaction

Pair processes, NC, energy-exchanging

scatteringEnergy-exchanging

scattering, light cluster breakup

NC (in-medium), equilibrium diffusion

electron (anti-)neutrinos heavy flavor neutrinos

Do the opacities close to the neutrinosphere matter?

● During accretion phase: diffusive flux from PNS core + accretion luminosity (typically dominant, well under control?)

● Heating conditions (critical time-scale) ratio extremely sensitive to luminosities and mean energies: tadv/theat~(LE

2)5/3

● Required accuracy: <5%

● Ye during wind phase even more sensitive (to difference of electron neutrino and antineutrino luminosity and mean energy)

● Example: significant effect of electron neutrino-antineutrino annihilation into heavy flavor neutrinos on shock radius

Buras et al. (2003)

With neutrino-antineutrino annihilation source for /

With neutrino-antineutrino annihilation source for /

shock radius

● Inverse effect: neutrino-nucleon scattering of heavy flavour neutrinos deep in the cooling region

● Recoil energy transfer from /

to the medium

allows stronger (anti-)e emission in cooling

region → increase in heating in gain region

● Further rate uncertainties: break-up of light clusters, improvement of bremsstrahlung process?

Effects of Neutrino Treatment on the Heating Conditions

Fraction of binding energy pumped into accreted material before it leaves the gain region

Müller et al. (2012a)

The Role of Non-Isoenergetic Neutrino-Nucleon Scattering

“radiative equilibrium”

sets temperature

stratification

addit

ional

heat

ing

by /

com

pens

ator

y

cooli

ngprot

o-ne

utro

n

star

cooling region

gain region

density

cooling region

lum

inos

ity

radius

Neutrino opacities matter and may explain discrepant results of different modeling groups!

Müller et al. (2012a)

Cooling Phase: Rate Sensitivities

● Mean energies: ● Qualitatively similar rate

sensitivities as during pre-explosion phase

● ee↔XX and recoil energy

transfer in -nucleon scattering lower / energies

● Cooling time-scale● opacities above nuclear matter

densities become important

● Drastic reduction of cooling time-scale due to nucleon correlations (how uncertain?)

● Importance of interaction potentials (Martínez-Pinedo et al. 2012, Roberts el. al. 2012) → EoS plays a direct role

Hüdepohl et al. (2010): 8.8 M⊙ progenitor with

O-Ne-Mg core (explodes in 1D)

“Bruenn opacities”

“full” opacities (including nucleon correlation)

Is the PNS interior spherically symmetric?

● LESA: Global lepton flux asymmetry in recent 3D models of the MPA group (Tamborra et al. 2014)

● Accretion instability or low-mode nature of PNS convection responsible?

Tamborra et al. (2014)

Implications

● Seed for global asymmetry in convective models?

● Helpful for neutrino-driven explosions?

● Ratio of electron neutrino to electron antineutrino luminosity determines Ye in outflow

● Asymmetric Ye in wind phase?

● Stability analysis required to corroborate LESA as a physical effect.

proton-rich

neutron-richWanajo et al. (2011)

Transition to wind phase in electron-capture supernova

Part II: Probing the Supernova Core with Neutrinos

What will observations of a Galactic supernova tell us about the supernova engine?

Neutrino Signal – Overview● Electron neutrino burst

after bounce

● Accretion phase:

● Gray-body law for /:

● Additional accretion contribution

for e and e

● e mean energy~neutron

star mass

● Signs of the explosion?

onset of explosion

Lacc~GM M /R

L~4 R2T 4

27 M8 model, spherical integration of the total neutrino flux

Müller et al. (2014)

Can we learn more about the dynamics?

25 M8

● Exploit temporal variations of the signal as fingerprints of multi-D instabilities!

● Exemplary cases:● Supernova models as

seen by the IceCube detector at a distance of 10kpc

● No non-linear flavor conversion & ordinary mass hierarchy assumed

flux flux

Detecting Shock Oscillations

Non-exploding 25 M8 model

● Sloshing motions result in quasi-periodic and asymmetric neutrino emission

● Sloshing frequency related to shock and proto-neutron star radius

● Modulations survive in 3D (Tamborra et al. 2013)

● Detectable in IceCube for up to ~10 kpc

● Opportunity to reconstruct shock trajectory!

Müller et al. (2014)

period∝ rshock3/ 2 ln

r shockrPNS

● Sloshing motions result in quasi-periodic and asymmetric neutrino emission

● Sloshing frequency related to shock and proto-neutron star radius

● Modulations survive in 3D (Tamborra et al. 2013)

● Detectable in IceCube for up to ~10 kpc

● Opportunity to reconstruct shock trajectory!

Detecting Shock Oscillations

Müller et al. (2014)

Signatures of the Explosion

oscillatory “sloshing”

27 M8 explosion model

● Explosion phase characterized by slowly-changing large-scale anisotropies

● → emission modulation periods >20 Hz

● Weak explosions: possible emission spikes due to “early fallback”

Signatures of the Explosion

radial velocity

entropy

15 M8 explosion model

● Explosion phase characterized by slowly-changing large-scale anisotropies

● → emission modulation periods >25ms

Signatures of the Explosion

15 M8 explosion model

● Explosion phase characterized by slowly-changing large-scale anisotropies

● → emission modulation periods >25ms

Signatures of the Explosion

● Explosion phase characterized by slowly-changing large-scale anisotropies

● → emission modulation periods >25ms

● Weak explosions: possible emission spikes due to “early fallback”

11.2M8 explosion model

Müller et al. (2014)

Signatures of the Explosion

● Explosion phase characterized by slowly-changing large-scale anisotropies

● → emission modulation periods >25ms

● Weak explosions: possible emission spikes due to “early fallback”

Müller et al. (2014)

Summary

● Accuracy on the percent level required to model the effect of neutrinos in supernovae correctly (heating, Ye in outflow)

● Some opacities may need to be revisited to achieve this goal:● heavy flavor neutrino reactions at neutrinospheric densities

(bremsstrahlung, light cluster breakup)

● PNS cooling: Nucleon interaction potentials and correlation effects at high densities (neutrino observations may help)

● Global lepton flux asymmetries need to be understood

● Time-frequency structure of the neutrino signal as a more powerful probe of supernova dynamics