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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/
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Core-Collapse Supernovaeonse
t
bounce
evolution of density profile
accretion
shock pro
pagation
proto-neu
tron star
Nakazato+ (2013)
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Supernova neutrinos• Clue for puzzle in supernova physics.
SN1987A@ Kamiokande
Burrows (1988)
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Explosion mechanism• SASI variability seen in neutrinos?
Tamborra+ (2013)
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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
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Light curves and spectra• Neutrino emission continues for 10 seconds.
Fischer+ (2012)Nakazato+ (2013)
νe
⎯νe
νx
(diffusion time scale)
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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)
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Neutronization burst• Shock dissociates nuclei.• Protons capture electrons emitting νe .
→ deleptonization
AA
AAA
Shock
:electron
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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
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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
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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.
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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!
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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/
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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
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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
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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
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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.
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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)
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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
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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
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Luminosity and mean energy
Totani+ (1998)This work
νe
⎯νeνx
13M☉
, Z = 0.02, trevive = 100 ms
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Neutrino spectra• Number luminosity
Totani+ (1998)This work
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Time integrated spectra
• They are similar to Fermi-Dirac distribution below 30 MeV.
• High energy tails are accretion phase origin.
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Systematics
• If the shock revival time is late, the total energy of emitted neutrino gets high.
shock revival lateearly
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Core mass dependence
• Total emission energy increase with the core mass of progenitor.→ correlation with the amount of accretion
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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!
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Detection status• The upper limit is near theoretical predictions.
invisible muon
atmospheric
largest allowed
SRN
Horiuchi+ (2009)Malek+ (2003)
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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)
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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
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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
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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
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Event rate (HK,10 years)
• Different trends in NL + NH vs. NL – NH plane.→ Key for shock revival time
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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