Supernova neutrinos and their implications for supernova physics

Ken’ichiro Nakazato（Tokyo University of Science）

in collaboration with H. Suzuki（Tokyo U of Sci.）,T. Totani, H. Umeda（U of Tokyo）,

K. Sumiyoshi（Numazu CT）

and S. Yamada（Waseda U）

MMCOCOS @ Fukuoka Univ., Dec. 4, 2013

http://www.tus.ac.jp/

Core-Collapse Supernovaeonse

t

bounce

evolution of density profile

accretion

shock pro

pagation

proto-neu

tron star

Nakazato+ （2013）

Supernova neutrinos• Clue for puzzle in supernova physics.

SN1987A@ Kamiokande

Burrows （1988）

Explosion mechanism• SASI variability seen in neutrinos?

Tamborra+ （2013）

Mass hierarchy

Normal Inverted

θ13 ≈ 0

θ13 ≠ 0

• Neutrino spectra for each time step• sin2 2θ13 ~ 0.1 （T2K, Daya Bay,…）

Kawagoe+ （2010）

excluded

⎯νe

Light curves and spectra• Neutrino emission continues for 10 seconds.

Fischer+ （2012）Nakazato+ （2013）

νe

⎯νe

νx

（diffusion time scale）

3 phases of neutrino emission

① neutronization burst~ O (10 ms)

② accretion phase~ O (100 ms)

③ cooling phase~ O (10 sec)νe

⎯νe

νx

① ② ③

Nakazato+ （2013）

Neutronization burst• Shock dissociates nuclei.• Protons capture electrons emitting νe .

→ deleptonization

AA

AAA

Shock

：electron

Accretion phase

proto-neutron star

• Gravitational potential of accreted matter converts to thermal energy.

• Neutrinos of all flavors are emitted by thermal process.

accretionshock

νν νν

νν

νν

νν

νν

collapse

Cooling phase

proto-neutron star

• Shock revives and propagates to outer layer.

• Heating by matter accretion stops.

• Luminosity and mean energy of neutrinos drop.

νν

νν

νν

When does shock revive?• Possibly characterizing explosion mechanism.

→ e.g. convection vs. SASI

• Whether the transition from accretion phase to cooling phase is early or late?→ Affecting the features of emitted neutrinos.

• More neutrinos would be emitted for later transition cases, because matter accretes more.

Supernova neutrino database• A comprehensive dataset for the long term

evolution of supernova neutrinos was made.

• It will be useful for simulations of future neutrino burst detection and predictions of relic supernova neutrino background.

• Parameterized by the shock revival time.

Now On-line!

Supernova neutrino database• A comprehensive dataset for the long term

evolution of supernova neutrinos was made.

• It will be useful for simulations of future neutrino burst detection and predictions of relic supernova neutrino background.

• Parameterized by the shock revival time.

Now On-line!

http://asphwww.ph.noda.tus.ac.jp/snn/

Spherically symmetric full GR hydrodynamics （Yamada 1997）

Metric：Misner & Sharp （1964）Radial mesh：255 non uniform zones

+Neutrino transport （Boltzmann solver）

（Yamada et al. 1999; Sumiyoshi et al. 2005）Species ：

νe ・⎯νe ・

νμ

( = ντ

) ・⎯νμ ( =⎯ντ

) Energy mesh ：

20 zones （0 – 300 MeV）

Reactions : e- + p ↔

n + νe , e+ + n ↔

p +⎯νe , ν + N ↔

ν + N,ν + e ↔

ν + e, νe + A ↔

A’ + e-, ν + A ↔

ν + A,

e- + e+ ↔

ν +⎯ν, γ* ↔

ν +⎯ν, N + N’ ↔

N + N’ + ν +⎯ν

ν radiation hydrodynamics

accretion phase

Proto-neutron star coolingMultigroup Flux Limited Duffusion scheme

（Suzuki 1994）Species ：

νe ・⎯νe ・

νμ

( = ντ

=⎯νμ =⎯ντ

) Energy mesh ：

20 zones （same with ν

rad-hydro.）

Reactions : e- + p ↔

n + νe , e+ + n ↔

p +⎯νe , ν + N ↔

ν + N,ν + e ↔

ν + e, νe + A ↔

A’ + e-, ν + A ↔

ν + A,

e- + e+ ↔

ν +⎯ν, γ* ↔

ν +⎯ν, N + N’ ↔

N + N’ + ν +⎯ν

(*) Equation of State by H. Shen is adopted for both computations.

coolingphase

Energy source of neutrinos

proto-neutron star

• Gravitational potential accreted matter + proto-neutron star cooling.

accretionshock

νν νν

νν

νν

νν

νν

collapse

),( tL εν),(.acc tL εν

＋

＝

),(cool tL εν

Inequality of emission

• The results of proto-neutron star simulation are the lower limit of neutrino emission.

• In 1D hydro simulation, amount of accretion is too much （thus fails to explode）.→ The results correspond to the upper limit.

),(),(),( coolmax.,accmax tLtLtL εεε ννν += >

),(.acc tL ενFrom 1D ν

radiation hydro simulation.

From proto- neutron star

cooling simulation.

Modeling neutrino light curve• Assuming shock revival time and fraction of

accretion to the maximum f (t).e.g.

shock revival time（trev ）： 100 ms after bounce

),()(),(),( coolmax.,acc tLtftLtL εεε ννν +=

⎪⎪⎩

⎪⎪⎨

⎧

⎟⎠⎞

⎜⎝⎛ −−=

0ms30

ms150exp

1

)(

　　　

　

　　　

ttf

（

t < 150 ms）

（150 ms < t < 350 ms）

（

t > 350 ms）

Shock revival time• Suggestions from observables.

Belczynski et al. (2012) Yamamoto et al. (2013)

NS mass distribution → 100-200 ms

explosion energy ＆56Ni yield→ 300-400 ms

We set trev = 100, 200, 300 ms

Progenitor models • mass：

M = 13 - 50M☉

（4 cases）• metallicity：

Z = 0.02, 0.004 （2 cases）

→ among total 8 models7 models: Supernovae1 model: Black Hole

（Failed supernova）→ 30M☉

, Z = 0.004

The maximum neutron star mass of adopted

equation of state

Luminosity and mean energy

Totani+ （1998）This work

νe

⎯νeνx

13M☉

, Z = 0.02, trevive = 100 ms

Neutrino spectra• Number luminosity

Totani+ （1998）This work

Time integrated spectra

• They are similar to Fermi-Dirac distribution below 30 MeV.

• High energy tails are accretion phase origin.

Systematics

• If the shock revival time is late, the total energy of emitted neutrino gets high.

shock revival lateearly

Core mass dependence

• Total emission energy increase with the core mass of progenitor.→ correlation with the amount of accretion

Implication from relic neutrino • The flux of neutrinos

and antineutrinos emitted by all core- collapse supernovae in the causally- reachable universe.

• Is it possible to study the shock revival time from supernova relic neutrinos?

time

z = 0

z = 1

z = 2

ν

We are here!

Detection status• The upper limit is near theoretical predictions.

invisible muon

atmospheric

largest allowed

SRN

Horiuchi+ （2009）Malek+ （2003）

Agenda• Estimation of the supernova relic neutrino

flux dealing shock revival time dependence.• Including a contribution of black-hole-

forming core-collapse.→ Failed supernovae– Their fraction is

indicated by GRB fraction, ∝ (1+z).

Yüksel & Kistler (2012)

Setups

• Cosmological parameters

• Star Formation rate: Hopkins & Beacom (2006)• Initial mass function: Salpeter A

• Neutrino OscillationNormal hierarchy and Inverted hierarchy

)(zRdEEd

EddN

dzdtdzc

dEdF

SN×′

′= ∫

ν

ν

νν

zdEEd

+=′

1ν

ν

Event rate （SK, 1 year）• If the shock revival

is late, event rate increases. But average energy is not sensitive.

• If failed SNe are included, both event rate and average energy gets higher.

100ms200ms

300ms

without Failed SNwith Failed SN

Shock revival vs. failed SNe• Dividing into 2 bins:

high and low energies.

• shock revival time ↗⇒

NL ↗, NH ↗

• with failed SNe⇒

NL ↗, NH ↗↗

NL NH

Event rate （HK,10 years）

• Different trends in NL + NH vs. NL – NH plane.→ Key for shock revival time

Summary• Neutrino detections will give clue for puzzle in

supernova physics.• We have constructed Supernova Neutrino

Database, where the predictions for various cases are included.

• Using the dataset, estimation for the flux of supernova relic neutrino is done.

• The flux reflects shock revival time, which should depend on the still unknown explosion mechanism.

Supernova neutrinos and their implications for�supernova physicsCore-Collapse SupernovaeSupernova neutrinosExplosion mechanismMass hierarchyLight curves and spectra3 phases of neutrino emissionNeutronization burstAccretion phaseCooling phaseWhen does shock revive?Supernova neutrino databaseSupernova neutrino databasen radiation hydrodynamicsProto-neutron star coolingEnergy source of neutrinosInequality of emission Modeling neutrino light curveShock revival timeProgenitor models Luminosity and mean energyNeutrino spectraTime integrated spectraSystematicsCore mass dependence Implication from relic neutrino Detection statusAgendaSetupsEvent rate （SK, 1 year）Shock revival vs. failed SNeEvent rate （HK,10 years）Summary