Probing neutrino physics with agalactic supernova
Amol Dighe
Tata Institute of Fundamental Research
Mumbai
CuTAPP 2005, Ringberg Castle, Germany, April 25-29, 2005
Probing neutrino physics with a galactic supernova – p.1/44
Why study a rare event(¿¿ Galactic SN: once in a few decades ??)
For neutrino mixing:Identifying normal / inverted mass hierarchyProbing extremely low values of �13
For SN astrophysics: Talk by R. Tomàs
Pointing to the SN in advanceTracking the shock wave propagation inside SN
For being prepared to observe relevant signals:Water Cherenkov / Ice CherenkovCarbon-based ScintillatorLiquid Ar
For long-term future:A guide for design parameters of future long baselineexperiments [superbeams / neutrino factories]
Probing neutrino physics with a galactic supernova – p.2/44
A Type II supernova
“Onion-shell” structure:
Probing neutrino physics with a galactic supernova – p.3/44
Trapped neutrinos before the collapseNeutrinos trapped inside “neutrinospheres” around � � 1010g/cc.
For �e; ��e
For all �; ��
G. Raffelt
Probing neutrino physics with a galactic supernova – p.4/44
The core collapseGravitational core collapse
Probing neutrino physics with a galactic supernova – p.5/44
The core collapseGravitational core collapse
Generation of a shock wave
Probing neutrino physics with a galactic supernova – p.5/44
Neutrino emission after the collapseNeutronization burst:Shock wave breaks up the nuclei ) e� capture enhanced�e emitted at the �e neutrinosphere.Duration: The first � 10 ms
�e; ��e; ��; ���; �� ; ���
Probing neutrino physics with a galactic supernova – p.6/44
Neutrino emission after the collapseNeutronization burst:Shock wave breaks up the nuclei ) e� capture enhanced�e emitted at the �e neutrinosphere.Duration: The first � 10 ms
Cooling through neutrino emission: �e; ��e; ��; ���; �� ; ���Duration: About 10 secEmission of 99% of the SN energy in neutrinos
Can be used for “pointing” to the SNin advance. (“Early warning”)
Probing neutrino physics with a galactic supernova – p.6/44
Neutrino emission after the collapseNeutronization burst:Shock wave breaks up the nuclei ) e� capture enhanced�e emitted at the �e neutrinosphere.Duration: The first � 10 ms
Cooling through neutrino emission: �e; ��e; ��; ���; �� ; ���Duration: About 10 secEmission of 99% of the SN energy in neutrinos
Can be used for “pointing” to the SNin advance. (“Early warning”)
¿¿¿ Explosion ???
Probing neutrino physics with a galactic supernova – p.6/44
Neutrino emission after the collapseNeutronization burst:Shock wave breaks up the nuclei ) e� capture enhanced�e emitted at the �e neutrinosphere.Duration: The first � 10 ms
Cooling through neutrino emission: �e; ��e; ��; ���; �� ; ���Duration: About 10 secEmission of 99% of the SN energy in neutrinos
Can be used for “pointing” to the SNin advance. (“Early warning”)
¿¿¿ Explosion ???
Talk by R. Tomàs
Probing neutrino physics with a galactic supernova – p.7/44
Initial neutrino spectraNeutrino fluxes:F 0�i = �0E0 (1 + �)1+��(1 + �) � EE0�� exp ��(�+ 1) EE0 �E0, �: in general time dependentKnown properties of the spectra:
Energy hierarchy: E0(�e) < E0(��e) < E0(�x)Spectral pinching: ��i > 2
E0(�e) � 10–12 MeVE0(��e) � 13–16 MeVE0(�x) � 15–25 MeV��i � 2–4
G. G. Raffelt, M. T. Keil, R. Buras, H. T. Janka
and M. Rampp, astro-ph/0303226 10 20 30 40
0.01
0.02
0.03
0.04
0.05
0.06
0.07
E(MeV)
Probing neutrino physics with a galactic supernova – p.8/44
Flavor-dependent neutrino fluxes
10
15
20
25
0 250 500 750
0 1 2 3 4 5 6
0 250 500 750
Time [ms]
10
15
20
25
0 1 2 3 4
⟨E⟩
0 1 2 3 4 5 6
0 1 2 3 4
L [
1052
erg
s-1
]
Time [s]
ν−eν−x
solid line: ��e
dotted line: ��x
Model hE0(�e)i hE0(��e)i hE0(�x)i �0(�e)�0(�x) �0(��e)�0(�x)
Garching (G) 12 15 18 0.8 0.8
Livermore (L) 12 15 24 2.0 1.6
G. G. Raffelt, M. T. Keil, R. Buras, H. T. Janka and M. Rampp, astro-ph/0303226
T. Totani, K. Sato, H. E. Dalhed and J. R. Wilson, Astrophys. J. 496, 216 (1998)
Probing neutrino physics with a galactic supernova – p.9/44
Propagation through matter
core
envelope
ρ=1010
0.1
10 14
12g/cc
ν
SUPERNOVA
VACUUMEARTH
10 km
10 R kpcsun 10000 km
Matter effects on neutrino mixing crucialFlavor conversions at resonances / level crossings
Probing neutrino physics with a galactic supernova – p.10/44
Level crossings during propagationNormal mass hierarchy Inverted mass hierarchy
H resonance: (�m2atm, �13), � � 103 g/ccIn � channel for normal hierarchy, �� channel for inverted hierarchyL resonance: (�m2�, ��), � � 10 g/ccAlways in � channel�m2 hierarchy ) Independent dynamics at resonances
Probing neutrino physics with a galactic supernova – p.11/44
Conversion probability at resonance
1−P
Pf
Pf
1−Pf
Core
Vacuum
Envelope
f
Pf � exp���2 � ; � �m22E sin2 2� os 2� � 1ne dnedr ��1 � 1) Pf � 1) Adiabatic resonance
Landau’1932, Zener’1932L resonance always adiabaticH resonance adiabatic for jUe3j2 >� 10�3,non-adiabatic for jUe3j2 <� 10�5
AD, A. Smirnov, PRD 62, 033007 (2000)Probing neutrino physics with a galactic supernova – p.12/44
Fluxes arriving at the EarthMixture of initial fluxes:F�e = pF 0�e + (1� p)F 0�x ;F��e = �pF 0��e + (1� �p)F 0�x ;4F�x = (1� p)F 0�e + (1� �p)F 0��e + (2 + p+ �p)F 0�x :Survival probabilities in different scenarios:
Case Hierarchy sin2�13 p �p
A Normal Large 0 os2��
B Inverted Large sin2�� 0C Any Small sin2�� os2��
“Small”: sin2�13 <� 10�5, “Large”: sin2�13 >� 10�3.Sensitivity to sin2�13 an order of magnitude better than currentreactor experiments !
Probing neutrino physics with a galactic supernova – p.13/44
SN87A
(Hubble image)
Confirmed the SN coolingmechanism through neutrinos
Number of events too small tosay anything concrete aboutneutrino mixing
Some constraints onSN parameters obtained
J. Arafune, J. Bahcall, V. Barger, M. Fukugita, B. Jegerlehner, M Kachelrieß,
C. Lunardini, D. Marfatia, H. Minakata, F. Neubig, D. Nötzold, H. Nunokawa,
G. G. Raffelt, K. Shiraishi, A. Smirnov, D. Spergel, A. Strumia, H. Suzuki,
R. Tomàs, J. V. F. Valle, B. Wood, T. Yanagida, M. Yoshimura, et al
Probing neutrino physics with a galactic supernova – p.14/44
Detecting a galactic SNEvents expected at Super-Kamiokande with a SN at 10 kpc:��ep! ne+: � 7000 – 12000�e� ! �e�: � 200 – 300�e +16 O ! X + e�: � 150–800
Some useful reactions at other detectors:
Carbon-based scintillator: � + 12C ! � +X + (15.11 MeV)
Liquid Ar: �e + 40Ar ! 40K� + e�
Probing neutrino physics with a galactic supernova – p.15/44
Identifying
neutrino mixing scenario
A ?? B ?? C ??
Probing neutrino physics with a galactic supernova – p.16/44
The task at hand
Measure the spectra, determine the mixing scenario.
A. Bandyopadhyay, AD, S. Choubey, G. Dutta, I. Gil-Botella, S. Goswami, D. Indumathi,
M. Kachelrieß, K. Kar, C. Lunardini, H. Minakata, M. V. N. Murthy, H. Nunokawa, G. Raffelt,
G. Rajasekaran, A. Rubbia, K. Sato, A. Smirnov, K. Takahashi, R. Tomàs, J. Valle, et al
��e
Probing neutrino physics with a galactic supernova – p.17/44
The task at hand
Measure the spectra, determine the mixing scenario.
A. Bandyopadhyay, AD, S. Choubey, G. Dutta, I. Gil-Botella, S. Goswami, D. Indumathi,
M. Kachelrieß, K. Kar, C. Lunardini, H. Minakata, M. V. N. Murthy, H. Nunokawa, G. Raffelt,
G. Rajasekaran, A. Rubbia, K. Sato, A. Smirnov, K. Takahashi, R. Tomàs, J. Valle, et al
C. Lunardini, A. Smirnov, JCAP 0306:009 (2003)
Poorly known initial spectra
Only final ��e spectrumcleanly available (till we haveliquid Ar)
Difficult to find a “clean” ob-servable, i.e. one indepen-dent of some assumptionsabout the initial spectra
Probing neutrino physics with a galactic supernova – p.17/44
Some possible observablesDuring neutronization burst: RB � NCC=NNCCase A ) RB=RB0 � jUe3j2 � 0:05
Broadening of spectra:pinched ! antipinched, i.e. � > 2! � < 2Pinching parameter 3hE2i=4hEi2:Information about the spectrum around the peak
Tail fraction: ftail = N(E > Etail)N(E > Eth)Information about the high-energy part of the spectrum
Difficult to find a “clean” observable, i.e. one independent of someassumptions about the initial spectra.
M. Kachelrieß, C. Lunardini, H. Minakata, H. Nunokawa, G. Raffelt,
K. Sato, A. Smirnov, K. Takahashi, R. Tomàs, J. Valle, et al
Probing neutrino physics with a galactic supernova – p.18/44
Exploiting Earth matter effectsNeutrinos Antineutrinos
10 20 30 40 50 60 70
2.5
5
7.5
10
12.5
15
10 20 30 40 50 60 70
2.5
5
7.5
10
12.5
15
E E
(�e, �x, mixed �) (��e, ��x, mixed ��)
�e ��e
Probing neutrino physics with a galactic supernova – p.19/44
Exploiting Earth matter effectsNeutrinos Antineutrinos
10 20 30 40 50 60 70
2.5
5
7.5
10
12.5
15
10 20 30 40 50 60 70
2.5
5
7.5
10
12.5
15
E E
(�e, �x, mixed �) (��e, ��x, mixed ��)
Total number of events (in general) decreasesCompare signals at two detectors
“Earth effect” oscillations are introducedScenarios B, C for �e, scenarios A, C for ��e
Probing neutrino physics with a galactic supernova – p.19/44
Comparing spectra at multiple detectors
C. Lunardini and A. Smirnov, NPB616:307 (2001)
Probing neutrino physics with a galactic supernova – p.20/44
IceCube as a co-detector with SK/HKIceCube primarily meant for neutrinos with energy >� 150 GeV
The number of Cherenkov photons increases beyond statisticalbackground fluctuations during a SN burst
This signal can be determined to a statistical accuracy of � 0:25%for a SN at 10 kpc.
The Earth effects may change the signal by � 0–10%.
The extent of Earth effectschanges by 3–4 % between theaccretion phase (first 0.5 sec)and the cooling phase.
Absolute calibration not essen-tial
Accretion phase
Cooling phase
Probing neutrino physics with a galactic supernova – p.21/44
Useful SN locations for SK-IC comparison
Earth effects detectable inregions (A) and (B)
AD, M. Keil, G. Raffelt, JCAP 0306:005 (2003)
Probing neutrino physics with a galactic supernova – p.22/44
At a single detector(Identifying Earth oscillation frequency)F��e = sin2�12F 0�x + os2�12F 0��e +�F 0 �A� sin2(�m2�Ly)
(F 0��e � F 0�x) sin 2���12 sin(2���12 � 2�12) (12:5=E)
Oscillation frequency: k� � 2�m2�LThe highest frequency in the “inverse energy” dependence of thespectrum
Completely independent of the primary neutrino spectra
Depends only on solar oscillation parameters, Earth density andthe distance travelled through the Earth
Probing neutrino physics with a galactic supernova – p.23/44
Fourier TransformPower spectrum: GN (k) = 1N ��Pevents eiky��2
Energy resolution is a crucial factor
Scintillation detector: a few thousand events
Water Cherenkov detector: a few ten thousand events
AD, M. Keil, G. Raffelt, JCAP 0306:006 (2003)
Probing neutrino physics with a galactic supernova – p.24/44
Passage through the Earth core
FD�e = sin2 �12 F 0�x + os2 �12 F 0�e + �F 0 7Xi=1 �Ai sin2(kiy=2) ;
i kiy �Ai1 �m=2 � 12 sin(2�12 � 4�m) sin(4� � 4�m) O(!)
2 (�m=2 + � ) os2(� � �m) sin(2�12 � 4�m) sin(2� � 2�m) O(!)
3 (�m + � ) sin(2�12 � 2�m) os4(� � �m) sin(2�m) O(!)
4 � � sin2(2� � 2�m) [ os(2�12 � 4�m)�� 12 sin(2�12 � 2�m) sin(2�m)℄ O(!2)
5 �m 12 sin(2�12 � 2�m) sin2(2� � 2�m) sin(2�m) O(!3)
6 (�m=2� � ) �2 sin(2�12 � 4�m) os(� � �m) sin3(� � �m) O(!3)
7 (�m � � ) sin(2�12 � 2�m) sin4(� � �m) sin(2�m) O(!5)
Probing neutrino physics with a galactic supernova – p.25/44
At a scintillation detector
Passage through the Earth core gives rise to extra peaks.
Model independence of peak positions:
Probing neutrino physics with a galactic supernova – p.26/44
At a water Cherenkov detector
High-k suppression:
Probing neutrino physics with a galactic supernova – p.27/44
Peak identificationStatistical fluctuations may "drown" peaks
Use area under the spectrum for peak identification
Quantifying "efficiency" of a detector
Probing neutrino physics with a galactic supernova – p.28/44
Efficiencies of detectors
High-k suppressionaffects the efficiency ofHK for 35Æ < � < 55Æ.(�: nadir angle)
Large number of eventscompensates forpoorer energy resolution
AD, M. Kachelrieß, G. Raffelt, R. Tomàs, JCAP 0401:004 (2004)
Probing neutrino physics with a galactic supernova – p.29/44
Observation of a Fourier peak in ��e
)Eliminate scenario B independently
of SN models !!!
Probing neutrino physics with a galactic supernova – p.30/44
Shock wave
for identifying
neutrino mixing scenario
Probing neutrino physics with a galactic supernova – p.31/44
Shock wave and level crossings
When shock wave passesthrough a resonance region,adiabatic resonances maybecome non-adiabatic for sometimescenario A ! scenario Cscenario B ! scenario C
May cause sharp changes in thefinal spectra even if the primaryspectra are unchanged /smoothly changing
R. C. Schirato, G. M. Fuller,
astro-ph/0205390
G. L. Fogli, E. Lisi, D. Montanino and
A. Mirizzi, PRD 68, 033005 (2003)
Probing neutrino physics with a galactic supernova – p.32/44
��e Survival probability
20 40 60 80 100 120
0.1
0.2
0.3
0.4
0.5
0.6
0.7
E E EE1b 2b 2a 1a
p_
E�!Shifts right as shock propa-gates to lower densities
Correspondence between densities and energies:
�i = mN�m2atm os 2�132p2GFYeEi � 600 g= m3 os 2�13 25 MeVEi 1Ye
For sharp changes in the density profile: �p = sin2(�a � �b) os2 ��
Probing neutrino physics with a galactic supernova – p.33/44
At a megaton water Cherenkov
“Double dip” feature for hEei“Double peak” feature for hE2e i=hEei2
R. Tomás, M. Kachelrieß, G. Raffelt, AD,
H. T. Janka, L. Scheck, JCAP09(2004)015
Probing neutrino physics with a galactic supernova – p.34/44
Single/double dip
“Single/double dip” robust underneutrino flux modelsmonotonically decreasing average energy
“Single/double dip” visible forsin2 2�13 >� 10�5In �e for normal hierarchyIn ��e for inverted hieratchy
Probing neutrino physics with a galactic supernova – p.35/44
Summary [Detector wishlist]
SN � spectra can help identifying the neutrino mixing scenario:normal / inverted mass hierarchysmall / large �13
A positive identification of the Earth effects rules out scenario B(inverted hierarchy � sin2�13 > 10�3) from ��e or scenario A(normal hierarchy � sin2�13 > 10�3) through �e.
comparison between multiple detectors [SK/MWC, IceCube]identifying earth matter oscillations [SK/MWC, LENA, liquid Ar]
Tracking the shock fronts “in neutrinos”recognizes the presence / absence of a reverse shockconfirms the scenario A [liquid Ar] or scenario B [MWC].determines the times the shocks pass through � � 102–104 g/cc
Talk by R. Tomàs
Probing neutrino physics with a galactic supernova – p.36/44
Extra slides
Probing neutrino physics with a galactic supernova – p.37/44
Splitting events into energy bins
Dip-times energy-bin dependent !!!
Probing neutrino physics with a galactic supernova – p.38/44
Tracking the shock fronts
At t � 4:5 sec, (reverse) shock at �40At t � 7:5 sec, (forward) shock at �40
Multiple energy bins ) the times the shock fronts reach differentdensities of � � 102–104 g/cc
Probing neutrino physics with a galactic supernova – p.39/44
Shock wave at SK
Probing neutrino physics with a galactic supernova – p.40/44
Time evolution of observablesPrimary spectra:F 0i (E) = �ihEii ��ii�(�i) � EhEii��i�1 exp���i EhEii�Number of events:
Nobs = N ����x hE��xi2�2��x �(���x + 2)�(���x) + os2 ��(���eg��e2 � ���xg��x2 )�
where gik = hE��x ik�ki �(�i) h��a; E1hEii�i; E2hEii�i�+ ��a; E3hEii�i; E4hEii�i�i
(Time dependence through the time evolution of E1; E2; E3; E4)Energy moments:
Emobs = N "���x hE��xi2+m�2+m��x �(���x + 2 +m)�(���x) + os2 ��(���eg��e2+m � ���xg��x2+m)#
Probing neutrino physics with a galactic supernova – p.41/44
Time dependence of observables
Model hE0(�e)i hE0(��e)i hE0(�x)i �0(�e)�0(�x) �0(��e)�0(�x)
L 12 15 24 2.0 1.6
G1 12 15 18 0.8 0.8
G2 12 15 15 0.5 0.5
Probing neutrino physics with a galactic supernova – p.42/44
Role of neutrinos in explosion
cooling
Neutrino heating
dM/dt
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Neutrino
70 km200 km
Proto−NeutronStar (n,p)
20 km
p
e
n Stalled Shock
Neutrinosphere�����������������������������������������������������������������������������������������������������������������������������������������������������������������
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Neutrino heating essential, but not enough
No spherically symmetric (1-D) simulations show robust explosions
Probing neutrino physics with a galactic supernova – p.43/44
Ingredients required for explosion
[ms]
R. Buras, H.-T. Janka, M. Rampp,
K. Kifonidis, astro-ph/0303171
Neutrino heating: higher neutrino opacity
Large scale convenction modes
Stiffer equation of state for the core
Rotation of the star
O. E. Bronson Messer, S. Bruenn, C. Cardall, M. Liebendoerfer,
A. Mezzacappa, W. Raphael Hix, F.-K. Thielemann et alProbing neutrino physics with a galactic supernova – p.44/44