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Nov 13, 2023 •275 likes •517 views

32 12/25-27 (arXiv:1907.01002) (D3 / ) with ( ),

  1. � 32 ���������� 12/25-27 ������������ ������������������ (arXiv:1907.01002) ����� (D3 �� / ����� ) with ���� ( ����� ), ���� ( �� ), ���� ( ��������� ), ����� ( ��� )

  2. 1. Introduction 2. Method 3. Result & Discussion 4. Summary

  3. Property of Neutrino � Neutral leptons � Weak interactions � Small mass � 3 flavors and antiparticles n e n µ n t n e n µ n t SK collaboration, 1998 � Neutrino oscillations n µ n µ n µ → n t w/o osc. n t n t n e n e w/ osc.

  4. Neutrino oscillations in core-collapse supernovae Neutrino oscillations are sensitive to coherent forward scatterings with background medium Collective neutrino Oscillations MSW effect (r � 10 2 - 10 3 km) (r> 10 3 km) Proto - neutron star n e r � 10 km n e e - n a n b n b n a n e e -

  5. The purpose of our research Vacuum neutrino oscillations and MSW effects are observed in neutrino experiments. SK collaboration, 1998 Borexino collaboration, 2018 w/o osc. w/ osc. However, there is no evidence of collective neutrino oscillations (CNO) → We discuss detectability of collective neutrino oscillations in future neutrino detectors

  6. 1. Introduction 2. Method 3. Result & Discussion 4. Summary

  7. Progenitor of Electron capture supernova (ECSN) H envelope Janka, 2012 He burning shell O-Ne-Mg ECSN is triggered by electron capture ECSN reactions at O-Ne-Mg core Progenitor mass is in 8-10 M sun The dilute envelop of ECSN-progenitor (8.8 M sun ) is suitable for collective neutrino oscillations

  8. Hydrodynamic simulation & Neutrino radiation log (density [g/cm^3]) Luminosity [10 51 erg/s ] Radius [km] Shock radius Time after bounce [ms] Mean Energy [MeV] Time after bounce [ms] This progenitor explodes even in the 1D model because of the dilute envelope Neutrino oscillations are calculated by using time snapshot of these quantities Time after bounce [ms]

  9. Neutrino oscillations in 3 flavor multiangle calculation Liuville-von Neumann equations of neutrino density matrices (Duan,2006): q p n sphere r q p Multi angle ( q p = 0) MSW matter potential: Vacuum Hamiltonian: U: PMNS matrix Neutrino self interactions: Mass hierarchy is unknown D m 232 >0: Normal hierarchy D m 232 <0: Inverted hierarchy

  10. 1. Introduction 2. Method 3. Result & Discussion 4. Summary

  11. Survival probability of n e at 1500 km after collective neutrino oscillations (CNO) Inverted( D m 2 Normal( D m 2 32 <0) 32 >0) CNO appears in both mass hierarchies CNO is suppressed in dense matter profiles

  12. Collective neutrino oscillations (CNO) & Spectral swap 231 ms, inverted mass hierarchy CNO Survival Probability of n e Spectral swap CNO occurs at 250 km where G F n n � < | D m 2 32 |/2E > n n : Total neutrino number density Spectral swap (green to blue) occurs after CNO, which increases energetic n e

  13. Neutrino spectra affected by oscillations Collective neutrino Oscillations MSW effect (r � 10 2 - 10 3 km) (r> 10 3 km) Proto - neutron star n e r � 10 km Mixing Mixing Final neutrino spectra are mixing of initial neutrino spectra

  14. Neutrino spectra on the earth Neutrino spectra after CNO are affected by MSW effects in outer layers Normal Inverted Normal Inverted ~ 0 n e ~ 0.3 n e MSW resonances ~ 0.3 n e ~ 0.7 n e MSW resonances ~ 0.7 n e ~ 0 n e n e n e 0 0 Fluxes of n e , n e on the earth: s 2 13 ~ 0, s 2 12 c 2 13 ~ 0.3, c 2 12 c 2 13 ~ 0.7

  15. n e spectrum on the earth 231 ms, inverted mass hierarchy Softened n e spectrum on the earth w/o CNO : e =1 → Hard spectra w/ CNO : 0< e <1 → Soft spectra e : Survival probability of n e after CNO

  16. Future neutrino detectors HK � Hyper-Kamiokande (HK) 200 kton, Water Cherenkov JUNO n e + p → e + + n � JUNO 20 kton, Liquid scintillator n e + p → e + + n n + p → d + g DUNE � DUNE 40 kton, Liquid Argon n e + 40 Ar → e - + 40 Kr *

  17. n e detection @ Hyper-Kamiokande(HK) Inverted mass hierarchy @15kpc Event number [1/50ms]: Soft N tar : Number of H 2 O : Flux of n e s : Cross section � E 2 Hardness ratio: The both event number and hardness ratio : # of E> E c are reduced by CNO : # of E< E c → The softened R H/L is preferable for detection of CNO E c =20 MeV

  18. n e detection in normal mass hierarchy Normal mass hierarchy @15kpc CNO make energetic n e Hard → Such n e can survive on the earth → Event number increases R H/L becomes hard w/o CNO : e =1 → soft spectra w/ CNO : 0< e <1 → Hard spectra

  19. n e observation in normal mass hierarchy @ DUNE Normal mass hierarchy @4kpc Soft w/o CNO : e =1 → Hard spectra w/ CNO : 0< e <1 → Soft spectra e : Survival probability of n e in e-x sector

  20. n e observation in inverted mass hierarchy @ DUNE Inverted mass hierarchy @2kpc Soft Hard 0< e <1, h =1 → Hard spectra 0< e <1 , 0< h <1 → Soft spectra e : Survival probability in e-x sector, h : Survival probability in e-y sector

  21. Summary of CNO detectability We summarize behaviors of hardness ratio R H/L Hierarchy Normal Inverted Spectrum Hard Soft Soft n e DUNE n e Soft Hard HK In the accretion phase, neutrino spectra naturally become hard → Softening neutrino spectrum is easy to distinguish Combination of HK and DUNE gives us softening R H/L in both hierarchy

  22. 1. Introduction 2. Method 3. Result & Discussion 4. Summary

  23. Summary � Neutrino self interactions certainly induce collective neutrino oscillations (CNO) in core-collapse supernovae � However, the signature of CNO has not been found in observations � We carry out numerical simulations of electron capture supernovae (8.8 M_sun) and discuss detectability of CNO � The softening hardness ratio traces spectral swap caused by CNO � In inverted mass hierarchy, HK can distinguish softening hardness ratio of n e within 15 kpc � In normal mass hierarchy, DUNE can clarify softening hardness ratio of n e within 4 kpc

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