Supernova Neutrinos Production, Propagation and Oscillations

Supernova neutrinos production, propagation and oscillations

Amol Dighe Tata Institute of Fundamental Research, Mumbai

Neutrino 2004, College de France, Paris, June 19, 2004

Supernova neutrinos – p.1/33 Production Neutrino emission during the core collapse and cooling Primary neutrino spectra and their model dependence Propagation Role of neutrinos in SN explosion Neutrino ﬂavour conversions in SN mantle and envelope Neutrino mixing scenarios and observed neutrino spectra Oscillations Earth matter effects on neutrino spectra Identiﬁcation of neutrino mixing scenario Learning about shock propagation

Supernova neutrinos – p.2/33 Neutrino production in core collapse SN

Supernova neutrinos – p.3/33 Before the collapse

½¼

Neutrinos trapped inside “neutrinospheres” around g/cc.

h E i < h E i < h E i

Escaping neutrinos:

e e Ü

Supernova neutrinos – p.4/33 ; ; ; ; ;

e e

During the core collapse

Neutronization burst:

Shock wave breaks up the nuclei µ e capture enhanced

e emitted at the e neutrinosphere.

Duration: The ﬁrst 10 ms

Supernova neutrinos – p.5/33 During the core collapse

Neutronization burst:

Shock wave breaks up the nuclei µ e capture enhanced

e emitted at the e neutrinosphere.

Duration: The ﬁrst 10 ms

; ; ; ; ;

Cooling through neutrino emission: e e Duration: About 10 sec Emission of 99% of the SN energy in neutrinos

Can be used for “pointing” to the SN in advance. (“Early warning”) A few hours before the explosion (SNEWS)

Supernova neutrinos – p.5/33 Initial neutrino spectra Neutrino ﬂuxes:

½· «

« E E

F «

E « E E

¼ ¼ ¼

E «

¼ , : in general time dependent Known properties of the spectra:

E < E < E

Energy hierarchy: ¼ e ¼ e ¼ Ü

« >

Spectral pinching:

0.07

¼ e – MeV 0.06

E ¼ e – MeV 0.05 0.04

¼ Ü – MeV 0.03

– i 0.02 G. G. Raffelt, M. T. Keil, R. Buras, H. T. Janka 0.01 E(MeV) and M. Rampp, astro-ph/0303226 10 20 30 40

Supernova neutrinos – p.6/33 Model dependent neutrino ﬂuxes

25 25

〉 20 20 E 〈 15 15

10 10

0 1 2 3 4 0 250 500 750

solid line: e −

] 6 ν 6

−e dotted line: Ü -1 ν 5 x 5 4 4 erg s 3 3 52 2 2

L [10 1 1 0 0 0 1 2 3 4 0 250 500 750 Time [s] Time [ms]

¨ ´ µ ¨ ´ µ

e e

¼ ¼

h E ´ µ i h E ´ µ i h E ´ µ i

e e Ü Model ¼ ¼ ¼

¨ ´ µ ¨ ´ µ

Ü Ü

¼ ¼ 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)

Supernova neutrinos – p.7/33 Neutrino propagation inside SN

Supernova neutrinos – p.8/33 Role of neutrinos in explosion

Neutrino heating Neutrino cooling p n Stalled Shock Proto−Neutron Star (n,p) e dM/dt Neutrinosphere 20 km 70 km 200 km

Neutrino heating essential, but not enough No spherically symmetric (1-D) simulations show robust explosions

Supernova neutrinos – p.9/33 Ingradients required for explosion

R. Buras, H.-T. Janka, M. Rampp, K. Kifonidis, astro-ph/0303171

[ms] 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 al Supernova neutrinos – p.10/33 Propagation through matter

SUPERNOVA EARTH VACUUM

envelope ν core

14 ρ=10 g/cc 10 10 12 0.1 10 km

10 R sun kpc 10000 km

Matter effects on neutrino mixing crucial Flavor conversions at resonances / level crossings

Supernova neutrinos – p.11/33 Level crossings during propagation Normalmasshierarchy Invertedmasshierarchy

¾ ¿

À Ñ

resonance: ( , ½¿ ), g/cc

aØÑ

In channel for normal hierarchy, channel for inverted hierarchy

Ä Ñ

resonance: ( , ), g/cc

Always in channel

Ñ hierarchy µ Independent dynamics at resonances

Supernova neutrinos – p.12/33 Conversion probability at resonance

1−Pf

Pf 1−Pf Pf

Envelope Core Vacuum

Ñ dÒ

È eÜÔ ;

E Ò dÖ

µ È µ

f Adiabatic resonance

Landau’1932, Zener’1932

Ä resonance always adiabatic

¾ ¿

À j Í j

resonance adiabatic for e ¿ ,

¾ 5

j Í j

non-adiabatic for e ¿

Supernova neutrinos – p.13/33 Fluxes arriving at the Earth Mixture of initial ﬂuxes:

¼ ¼

F Ô F Ô F ;

e Ü

¼ ¼

F Ô F Ô F ;

e Ü

¼ ¼ ¼

F Ô F Ô F Ô Ô F :

e e Ü

Survival probabilities in different scenarios:

Ô Ô

Case Hierarchy ½¿

A Normal large 0

B Inverted large 0

C Any small

¾ ¾

¿ ¿

< >

“Small”: ½¿ , “Large”: ½¿ .

AD, A. Smirnov, PRD 62, 033007 (2000)

Supernova neutrinos – p.14/33 SN87A

Conﬁrmed the SN cooling mechanism through neutrinos Number of events too small to say anything concrete about neutrino mixing Some constraints on SN parameters obtained

(Hubble image) 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

Supernova neutrinos – p.15/33 Detecting a galactic SN Events expected at Super-Kamiokande with a SN at 10 kpc:

Ô ! Òe

e : 7000 – 12000

e ! e : 200 – 300

½6

Ç ! X e

e : 150–800

Some useful reactions at other detectors:

½¾

Carbon-based scintillator: C ! X (15.11 MeV)

4¼ 4¼

AÖ ! Ã e

Liquid Ar: e

Supernova neutrinos – p.16/33 Distinguishing neutrino mixing scenarios

Supernova neutrinos – p.17/33

The task at hand

Measure the spectra, determine the mixing scenario.

A. Bandyopadhyay, S. Choubey, I. Gil-Botella, S. Goswami, M. Kachelrieß, K. Kar, C. Lunardini, H. Minakata, H. Nunokawa, G. Raffelt, A. Rubbia, K. Sato, A. Smirnov, K. Takahashi, R. Tomàs, J. Valle, et al

Supernova neutrinos – p.18/33 The task at hand

Measure the spectra, determine the mixing scenario.

Poorly known initial spectra

Only final e spectrum cleanly available. Difficult to find a “clean” ob- servable, i.e. one independent of some assumptions about the initial spectra

C. Lunardini, A. Smirnov, JCAP 0306:009 (2003) Supernova neutrinos – p.18/33

e e

Exploiting Earth matter effects Neutrinos Antineutrinos 15 15

12.5 12.5

10 10

7.5 7.5

5 5

2.5 2.5 E 10 20 30 40 50 60 70 E 10 20 30 40 50 60 70

( e , Ü , mixed )( e , Ü , mixed )

Supernova neutrinos – p.19/33 Exploiting Earth matter effects Neutrinos Antineutrinos 15 15

12.5 12.5

10 10

7.5 7.5

5 5

2.5 2.5 EE 10 20 30 40 50 60 70 10 20 30 40 50 60 70

( e , Ü , mixed )( e , Ü , mixed )

Total number of events (in general) decreases Compare signals at two detectors “Earth effect” oscillations are introduced

Scenarios B, C for e , scenarios A, C for e

Supernova neutrinos – p.19/33 Comparing spectra at multiple detectors

C. Lunardini and A. Smirnov, NPB616:307 (2001)

Supernova neutrinos – p.20/33 IceCube as a co-detector with SK/HK IceCube primarily meant for individual neutrinos with energy

> GeV

For a SN burst at 10 kpc, the luminosity can be determined to a

statistical accuracy of : % over and above the statistical background ﬂuctuations

The Earth effects may change the signal by – %.

The extent of Earth effects changes by 3–4 % between the accretion phase (ﬁrst 0.5 sec) and the cooling phase. Absolute calibration not essential.

AD, M. Keil, G. Raffelt, JCAP 0306:005 (2003)

Supernova neutrinos – p.21/33 At a single detector (Identifying Earth oscillation frequency)

¾ ¾ ¼ ¾ ¼ ¼

F F F F A Ñ Ä Ý

½¾ ½¾

Ü e

¼ ¼

F F : =E

( ) ½¾ ( )

½¾ ½¾

e Ü

k Ñ Ä

Oscillation frequency:

The highest frequency in the “inverse energy” dependence of the spectrum Completely independent of the primary neutrino spectra: depends only on solar oscillation parameters, Earth density and the distance travelled through the Earth Fourier transform: peak in the power spectrum

¬ ¬

ik Ý

¬ ¬

G k e

eÚ eÒØ×

Æ AD, M. Keil, G. Raffelt, JCAP 0306:006 (2003)

Supernova neutrinos – p.22/33 At a scintillation detector Passage through the Earth core gives rise to extra peaks. Model independence of peak positions:

AD, M. Kachelrieß, G. Raffelt, R. Tomàs, JCAP 0401:004 (2004)

Supernova neutrinos – p.23/33 At a water Cherenkov detector

High-k suppression:

Supernova neutrinos – p.24/33 Efﬁciencies of detectors

High-k suppression affects the efﬁciency of

Æ Æ

HK for < < .

( : nadir angle) Large number of events compensates for poorer energy resolution

AD, M. Kachelrieß, G. Raffelt, R. Tomàs, JCAP 0401:004 (2004)

Observation of a Fourier peak in e Eliminate scenario B independently of SN models !!!

Supernova neutrinos – p.25/33 Neutrinos for SN astrophysics

Pointing to the SN in advance

Learning about the shock wave

Supernova neutrinos – p.26/33 Pointing to the SN in advance (at SK)

J. Beacom and P. Vogel, PRD60:033007 (1999) Needed if no optical observation

Ô ! Òe

e : nearly isotropic background

e ! e : forward-peaked “signal”

Æ = Æ

Background-to-signal ratio: B Ë –

Æ = Æ

Decrease B Ë : neutron tagging with Gd

Pointing accuracy improved 2–3 times using Gd R. Tomàs, D. Semikoz, G. Raffelt, M. Kachelrieß, AD, PRD 68, 093013 (2003). »degÖee

95 GADZOOKS ` (Gadolinium Antineutrino Detector Zealously Outperforming Old Kamiokande, Super!) J. F. Beacom and M. R. Vagins, hep-ph/0309300

¯ Øag Supernova neutrinos – p.27/33 Observing the shock wave “in neutrinos”

15 14 0.5 s 13 1.0 s 12 )] 2.0 s 3 11 When shock wave passes 10 5.0 s 9 10.0 s 8 20.0 s through a resonance 7 6 region, adiabatic 5 4 3 resonances may become log[Density (g/cm 2 1 0 non-adiabatic for some -1 105 106 107 108 109 1010 1011 time Radius (cm)

scenario A ! scenario C

scenario B ! scenario C 0.6 (a) (b) 0.4 May cause sharp changes

0.2 in the ﬁnal spectra even if the primary spectra are 0.0 0.6 (c) unchanged / smoothly

CC/NC Ratio 0.4 (d) changing

0.2 R. C. Schirato, G. M. Fuller, astro-ph/0205390 0.0 0 5 10 0 5 10

tpb (s)

Supernova neutrinos – p.28/33 Detection of the shock wave in the mantle

Sudden jumps in the

neutrino spectra µ

neutrino mixing scenario Time the shock wave passed through the

region g/cc.

G. L. Fogli, E. Lisi, D. Montanino and A. Mirizzi, PRD 68, 033005 (2003)

Supernova neutrinos – p.29/33 Reverse shock

1e+14

1e+12

1e+10

1e+08

1e+06 density in g/cc

10000

100

1 1e+06 1e+07 1e+08 1e+09 1e+10 radius in cm H.-T. Janka, L. Scheck

Supernova neutrinos – p.30/33 Signatures of a reverse shock (at HK)

Only for scenario B !!

AD, H.-T. Janka, M. Kachelrieß, G. Raffelt, L. Scheck, R. Tomàs

Supernova neutrinos – p.31/33 Summary Primary neutrino spectra: ﬂavor and model dependence Role of neutrinos in SN explosion: important, but more ingradients needed for a successful explosion Flavor conversions inside SN sensitive to normal vs. inverted

hierarchy and “small” vs. “large” mixing angle ½¿ . A positive identiﬁcation of Earth effects on antineutrinos: a model

independent way of ruling out inverted hierarchy and large ½¿ . Comparison of signals at multiple detectors (HK & IceCube) Identifying modulations in a single detector (energy resolution vs. size)

Advance SN pointing accuracy with neutrinos less than 10Æ Improved 2–3 times using Gd to tag neutrons.

Observing the shock wave in neutrinos µ features of shock wave and neutrino mixing scenarios

Supernova neutrinos – p.32/33 Things to do while waiting for a SN Better theoretical understanding of neutrino transport inside the SN and the explosion mechanism More accurate measurements of the neutrino mixing parameters Tuning of long-term detectors to observe SN neutrino signals

Supernova neutrinos – p.33/33 Things to do while waiting for a SN Better theoretical understanding of neutrino transport inside the SN and the explosion mechanism More accurate measurements of the neutrino mixing parameters Tuning of long-term detectors to observe SN neutrino signals

A rare event is a lifetime opportunity – Anon

Supernova neutrinos – p.33/33