neutrino oscillation in failed supernovae€¢ failed sn is faint in em, but bright in...
TRANSCRIPT
Neutrino oscillation�in Failed Supernovae"
Masamichi Zaizen1 (master’s 1st in Umeda lab.)"
Takashi Yoshida1, Kohsuke Sumiyoshi2," Hideyuki Umeda1"
1"
新学術「地下素核研究」第4回超新星ニュートリノ研究会"" "2018/1/8 @四季の湯強羅静雲荘 "
1:University of Tokyo, 2:Numazu College of Tech."
• Failed supernova"• Neutrino oscillation"
– (Vacuum oscillation)"– MSW effect"– Collective oscillation"
• Methods"• Results"• Summary"• Future work"
2"
Outline"
Massive star undergoes core-collapse."Shock wave stalls due to accretion matter.""In failed SNe, the shock wave can not revive due to heavy infall of outer layer."The proto-neutron star evolves into a black hole."
PNS Failed
Success
Shock stallsBH"
formation"
explosion"
3"
What is Failed Supernova?"
4"
Example for a failed SN ?"
N6946-BH1"25M¤, Red super giant, 6Mpc, Cygnus & Cepheus"
(c) NASA"
Gerke et al. 2015, Adams et al. 2017"
• Failed SN is faint in EM, but bright in neutrino."• Surrounding matter continues to accrete onto the PNS."• Neutrino emission stops when covering neutrino sphere
with BH event horizon formed in the center. "
• Neutrino spectra depend on EoS of high temperature and high density, so the observation enables us to understand it."
• Neutrinos are the important tool to get information on failed SNe."
• How many neutrinos do we observe on the Earth?"
5"
Failed SNe and Neutrinos"
6"
Mass hierarchy is not yet known. "(We’re looking forward to this solution.)"We assume two hierarchy cases in this work."
m12
m32
m22
inverted�hierarchy
m32
�m?+
-�m?
normal�hierarchy
2. Neutrino oscillation"
And we choose the modified flavor basis:"
Dighe et al. 2000, Dasgupta et al. 2008"
⌫x
= cos ✓23⌫µ � sin ✓23⌫⌧
⌫y
= sin ✓23⌫µ + cos ✓23⌫⌧
Then νx doesn’t include ν3 and θ13."Thereby νx isn’t affected by the oscillation associated with θ13, ∆m13." ex.) H resonance, 2 flavor collective…"
⌫e
$ ⌫y
⌫e
$ ⌫x
1-to-1 oscillation sets"
• MSW effect (the matter oscillation)"
7"
2. Neutrino oscillation"
P PNH sin2 ✓13 sin
2 ✓12 cos2 ✓13 cos2 ✓12IH cos2 ✓13 sin
2 ✓12 sin2 ✓13 cos2 ✓12
Survival probability of electron neutrino after undergoing adiabatic MSW H and L resonances."Shock wave effects don’t exist in failed SNe, unlike success SNe."
cos
2 ✓13 ⇠ 1
cos
2 ✓12 ⇠ 0.7
�2
�1
�3
�3
�2
�1
ne
m2
L
H
(SN core)(SN surface)
← inverted case"" normal case →"
�2
�1
�3�3
�2
�1
ne
m2
L
H
(SN core)(SN surface)
• Collective oscillation(Self-interaction effect)"
8"
2. Neutrino oscillation"
The collective oscillation is due to ν-ν inteaction and causes the spectral splits."This effect is important near the supernova core."
r
Neutrino�sphere
R� �interaction" ν"
ν"PNS"
Bulb model"
0 1 2 3 4 5 6 7 8 9
10
0 20 40 60 80 100
Num
ber [×
1055
]
Energy: E [MeV]
ix init.iy init.ie init.
ixiyie
r~O(100, 1000 km)"
�e ,p
vx ,q vx ,p
�e ,q
We obtain the flavor evolutions by solving the following equation of motion for the density matrix;"
9"
In this work, we assume the single-angle approximation. This approximation is that wave functions don’t depend on the angle of incidence. "
VO" MSW" Collective (non-linear term)"
i@t⇢p =
+U
M2
2pU†
+
p2GFL+
p2GF
Zd
3q
(2⇡)3(1� cos ✓pq)
�n⌫(q)⇢q � n⌫(q)⇢q
, ⇢p
�
3. Method"
The multi-angle simulation is … under construction."I face several difficulties and the results are incomplete."
• Calculation by Sumiyoshi"• 40M¤、EoS:LS220、1D model"
– Sumiyoshi et al. 2007, 2008"• Top left figure shows neutrino
luminosity."• Bottom left figure shows
neutrino averaged energy."• These values continue to
increase after core bounce."
• At several time steps, we carry post-process calculation in the normal and inverted hierarchy."
• t = 30, 100, 200, 300" , 400, 500, 600, 750 ms"
10"
Using model"
0 2 4 6 8
10 12 14 16 18 20
0 0.2 0.4 0.6 0.8 1
Lum
inos
ity [1
052 e
rg/s
]
time after bounce [sec]
iei-eixpurple: e"
green: e"blue: x"
_"
0
5
10
15
20
25
30
35
0 0.2 0.4 0.6 0.8 1
Aver
age
ener
gy <
Ei>
[MeV
]
time after bounce [sec]
iei-eix
time after core bounce [sec]"
11"
Result ex.: 600ms, Neutrino, IH & NH"
0 1 2 3 4 5 6 7 8 9
10
0 20 40 60 80 100
Num
ber [× 1
055]
Energy: E [MeV]
ix init.iy init.ie init.
ixiyie
red : e"green: x"blue : y"
Energy [MeV]"
0 1 2 3 4 5 6 7 8 9
10
0 20 40 60 80 100
Num
ber [× 1
055]
Energy: E [MeV]
ix init.iy init.ie init.
ixiyie
red : e"green: x"blue : y"
Energy [MeV]"
0 1 2 3 4 5 6 7 8 9
10
0 20 40 60 80 100
Num
ber [×
1055
]
Energy: E [MeV]
ix init.iy init.ie init.
ixiyie
red : e"green: x"blue : y"
Inverted hierarchy"
0 1 2 3 4 5 6 7 8 9
10
0 20 40 60 80 100
Num
ber [×
1055
]
Energy: E [MeV]
ix init.iy init.ie init.
ixiyie
red : e"green: x"blue : y"
Normal hiearchy"
0 1 2 3 4 5 6 7 8 9
10
0 20 40 60 80 100
Num
ber [×
1055
]
Energy: E [MeV]
Initial neutrino spectra
ie init.ix init.iy init.
Initial spectra"
red : e"green: x"blue : y"
Collective"
MSW resonance"
12"
Result ex.: 600ms, Antineutrino, IH & NH"
0
1
2
3
4
5
6
7
8
9
0 20 40 60 80 100
Num
ber [× 1
055]
Energy: E [MeV]
ix init.iy init.ie init.
ixiyie
red : e"green: x"blue : y"
Energy [MeV]"
0
1
2
3
4
5
6
7
8
9
0 20 40 60 80 100
Num
ber [×
1055
]
Energy: E [MeV]
Initial anti-neutrino spectra
ie init.ix init.iy init.
Initial spectra"
red : e"green: x"blue : y"
0
1
2
3
4
5
6
7
8
9
0 20 40 60 80 100
Num
ber [× 1
055]
Energy: E [MeV]
i-x init.i-y init.i-e init.
i-xi-yi-e
red : e"green: x"blue : y"
Energy [MeV]"
0
1
2
3
4
5
6
7
8
9
0 20 40 60 80 100
Num
ber [×
1055
]
Energy: E [MeV]
i-x init.i-y init.i-e init.
i-xi-yi-e
Normal hiearchy"
red : e"green: x"blue : y"
0
1
2
3
4
5
6
7
8
9
0 20 40 60 80 100
Num
ber [×
1055
]
Energy: E [MeV]
i-x init.i-y init.i-e init.
i-xi-yi-e
red : e"green: x"blue : y"
Inverted hierarchy"
Collective"
MSW resonance"
• Oscillation effects are qualitatively same at the time except for the neutronization burst at t = 30 ms."
"• At the neutronization burst, collective effects are
suppressed."– Due to the excess of electron neutrinos."– Therefore the differences occur between two
hierarchies by MSW."
13"
Results at other time steps."
0 10 20 30 40 50 60 70 80 90
100
0 10 20 30 40 50
Num
ber [×
1055
]
Energy: E [MeV]
Initial neutrino spectra
ix init.i-e init.ie init.red : e"
blue : e"green: x"
-"
⌫e
⌫e
$ ⌫x
⌫x
Pair conversion -> no collective"
• Neutrinos arrive at the Earth."• How many electron antineutrinos are detected by
Super-Kamiokande?"• Super-Kamiokande have a high sensitivity to
inverse beta decay with water Cherenkov detector."
⌫̄e + p ! n+ e+
14"
Detectionability at Super-Kamiokande"
�
�
� �e_
50 kpc"
Abe et al. 2011"
• Event rate of antineutrinos by Super-Kamiokande"– Np : proton number" = fiducial volume 22.5 kton"– d : distance to Failed SN (LMC, assume 50 kpc)"– Eth : threshold energy" = 4.79 MeV (3.5 MeV for recoil electrons)"– φ(E) : spectrum at the detector"– σ(E) : cross section of IBD (Strumia et al. 2003)"
15"
Detectionability at Super-Kamiokande"
dN⌫
dt=
Np
4⇡d2
Z 1
Eth
�(E)�(E)dE
0
50
100
150
200
250
300
350
0 100 200 300 400 500 600 700 800
accu
mul
ated
neu
trino
eve
nt [n
umbe
r]
times after bounce: t [ms]
inverted hierarchynormal hierarchy
no oscillation 0
100
200
300
400
500
600
700
0 100 200 300 400 500 600 700 800
even
t rat
e [n
umbe
r /se
c]
times after bounce: t [ms]
inverted hierarchynormal hierarchy
no oscillation
Hundreds of neutrinos are detected without EM counterpart.""Event number rate is same in normal and inverted hierarchy."
– collective effect and H resonance cancel each other in inverted hierarchy."
16"
Event rate at Super-Kamiokande"
• Deep Underground Neutrino Experiment"• A next generation detector in the United States."• Finish all construction by 2028."• DUNE have a high sensitivity to Charged-Current reaction
with liquid argon."
17"
Detectionability at DUNE"
40Ar + ⌫e !40 K⇤ + e�
• How many electron neutrinos are detected by DUNE ?"
• Event rate of neutrinos by DUNE"– NAr : Argon number" = fiducial volume 4×10 kton"– d : distance to Failed SN (LMC, assume 50 kpc)"– Eth : threshold energy" = 8.28 MeV (5 MeV electron cut-off)"– φ(E) : spectrum at the detector"– σ(E) : cross section of CC (Suzuki et al. 2013)"
18"
Detectionability at DUNE"
dN⌫
dt=
NAr
4⇡d2
Z 1
Eth
�(E)�(E)dE
0
200
400
600
800
1000
1200
1400
0 100 200 300 400 500 600 700 800
even
t rat
e [n
umbe
r /se
c]
times after bounce: t [ms]
inverted hierarchynormal hierarchy
no oscillation 0
100
200
300
400
500
600
0 100 200 300 400 500 600 700 800
accu
mul
ated
neu
trino
eve
nt [n
umbe
r]
times after bounce: t [ms]
inverted hierarchynormal hierarchy
no oscillation
"• Event number is same in normal and inverted hierarchy."
– Spectra are different between two hierarchies."– Why?"
19"
Event rate at DUNE"
20"
Cross section of CC reaction"
Suzuki et al. 2013"
Cross section in DUNE case"(CC reaction)"
Cross section increases in the order with energy."
0 1 2 3 4 5 6 7 8 9
10
0 20 40 60 80 100
Num
ber [×
1055
]
Energy: E [MeV]
ix init.iy init.ie init.
ixiyie
red : e"green: x"blue : y"
Energy [MeV]"
Inverted mass hierarchy"
0 1 2 3 4 5 6 7 8 9
10
0 20 40 60 80 100
Num
ber [×
1055
]
Energy: E [MeV]
ix init.iy init.ie init.
ixiyie
Normal mass hiearchy"
red : e"green: x"blue : y"
Energy [MeV]"
21"
Future work"
The multi-angle approximation?"
22"
Future work"
VO" MSW" Collective (non-linear term)"
i@t⇢p =
+U
M2
2pU†
+
p2GFL+
p2GF
Zd
3q
(2⇡)3(1� cos ✓pq)
�n⌫(q)⇢q � n⌫(q)⇢q
, ⇢p
�
d
dtP =
"+!B + �D
vr,u+
p2GF
2⇡R2⌫
R2⌫
2r2
ZdE0du0
✓1
vr,uvr,u0� 1
◆�n⌫P � n⌫P
�#⇥ P
multi-angle approximation"polarization vector"
• verify the multi-angle matter suppression"
longer path to the same radius r1"
experience larger matter effect."
vr,u = cos ✓ =
r1� sin
2 ✓RR2
⌫
r2
Neutrino sphere
radius r1
�
• How large do we use the angle bin?"– a lack of angle samplings causes the artificial
collective oscillations."– good resolution :Nθ ~ O(103). 1000 ?, 2000 ?, …5000 ?"
23"
Future work"
0.4
0.42
0.44
0.46
0.48
0.5
0.52
0.54
0.56
0.58
100 150 200 250 300 350 400
l ee
r [km]
Nu = 500Nu = 1000Nu = 1500Nu = 2000
multi-angle"
8⇥NE ⇥N✓ ⇥ 2 . 1, 000, 0001D × 2D calculation.
single-angle"
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0 200 400 600 800 1000 1200 1400
l ee
Radius [km]
10 MeV
• We calculate 3-flavor neutrino oscillation for 1-D failed supernova model."
• Hundreds of neutrinos and antineutrinos are detected from a failed SN located in LMC (50 kpc)."
• The event numbers of neutrino and antineutrino are identical in both hierarchy cases."– High energy components are dominant at DUNE."
• We tackle the multi-angle approximation."
24"
Summary"