Supernova Neutrinos Production, Propagation and Oscillations
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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 ½¼ g/cc. hE i < hE i < hE 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·« ¨ ´½ · « µ E E ¼ ¼ F ÜÔ ´« · ½µ i E ´½ · « µ E E ¼ ¼ ¼ E « ¼ , : in general time dependent Known properties of the spectra: E ´ µ < E ´ µ < E ´ µ Energy hierarchy: ¼ e ¼ e ¼ Ü « > ¾ Spectral pinching: i 0.07 E ´ µ ½¼ ½¾ ¼ e – MeV 0.06 E ´ µ ½¿ ½ ¼ e – MeV 0.05 0.04 E ´ µ ½ ¾¼ ¼ Ü – MeV 0.03 « ¾ – 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 hE ´ µi hE ´ µi hE ´ µi 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 1012 0.1 10 km 10 Rsun 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 ½¼ resonance: ( , ½¿ ), g/cc aØÑ In channel for normal hierarchy, channel for inverted hierarchy ¾ Ä ¡Ñ ½¼ resonance: ( , ¬ ), g/cc ¬ Always in channel ¾ ¡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 ½ ¾ ¾ ¡Ñ ×Ò ¾ ½ dÒ e È eÜÔ ; f ¾ ¾E ¾ Ò dÖ e ½ µ È ½ µ f Adiabatic resonance Landau’1932, Zener’1932 Ä resonance always adiabatic ¾ ¿ > À jÍ j ½¼ resonance adiabatic for e¿ , ¾ 5 < jÍ j ½¼ non-adiabatic for e¿ Supernova neutrinos – p.13/33 Fluxes arriving at the Earth Mixture of initial fluxes: ¼ ¼ F ÔF · ´½ ÔµF ; e e Ü ¼ ¼ F ÔF · ´½ ÔµF ; e e Ü ¼ ¼ ¼ F ´½ ÔµF · ´½ ÔµF · ´¾ · Ô · ÔµF : Ü e e Ü Survival probabilities in different scenarios: ¾ ×Ò ¢ Ô Ô Case Hierarchy ½¿ ¾ ¢ A Normal large 0 ¬ ¾ ×Ò ¢ B Inverted large ¬ 0 ¾ ¾ ×Ò ¢ ¢ C Any small ¬ ¬ ¾ ¾ ¿ ¿ < > ×Ò ¢ ½¼ ×Ò ¢ ½¼ “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 ! à · e Liquid Ar: e Supernova neutrinos – p.16/33 Distinguishing neutrino mixing scenarios Supernova neutrinos – p.17/33 e 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. 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 Poorly known initial spectra Only final e spectrum cleanly available. Difficult to find a “clean” ob- servable, i.e. one indepen- dent 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 > ½¼ GeV For a SN burst at 10 kpc, the luminosity can be determined to a statistical accuracy of ¼:¾% over and above the statistical background fluctuations The Earth effects may change the signal by ¼–½¼%. The extent of Earth effects changes by 3–4 % between the accretion phase (first 0.5 sec) and the cooling phase. Absolute calibration not essen- tial. 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 ¾ F ×Ò ¢ F · ¢ F · ¡F A ×Ò ´¡Ñ ÄÝ µ ½¾ ½¾ ¨ e ¨ Ü e ¨ ¨ ¼ ¼ F F ×Ò ¾¢ ×Ò´¾¢ ¾¢ µ ½¾:=E ( ) ½¾ ( ) ½¾ ½¾ e Ü ¾ k ¾¡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 ¬ ¬ È ¾ ½ ik Ý ¬ ¬ G ´k µ e Æ 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) µ 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 ¿¼ ¼ Background-to-signal ratio: B Ë – Æ =Æ Decrease B Ë : neutron tagging with Gd ½ Pointing accuracy improved 2–3 times using Gd R. Tomàs, D.