Neutrino Signatures from 3D Models of Core-Collapse Supernovae

Transcription

1 Neutrino Signatures from 3D Models of Core-Collapse Supernovae Irene Tamborra Niels Bohr Institute, University of Copenhagen nueclipse Knoxville, August 20, 2017

2 Outline Supernova explosion mechanism Hydrodynamical instabilities and detection perspectives Lepton number emission self-sustained asymmetry Consequences on neutrino flavor conversions Conclusions

3 Core-Collapse Supernova Explosion Implosion (Collapse) Neutrinos carry 99% of the 53 released energy (~ 10 erg). Explosion neutrino cooling by diffusion Neutrino energies: ~ 10 MeV. Neutrino emission time: ~ 10 s.

4 Delayed Neutrino-Driven Explosion Shock wave forms within the iron core. It dissipates energy dissociating iron layer. Neutrinos provide energy to stalled shock wave to start re-expansion. O Ni Shock revival O ν n, p ν O Convection and shock oscillations (standing accretion shock instability, SASI) enhance efficiency of neutrino heating and revive the shock. Shock wave Proto-neutron star n, p, α ν ν Recent review papers: Janka (2017). Mirizzi, Tamborra et al. (2016).

5 SASI Detection Perspectives (27 M ) sun Strong signal modulation (optimistic observer direction) 456)+78-9 : ("" 01)2.3) '"" &"" %"" $"" #""!"" * )!'+, -./ Weak signal modulation (pessimistic observer direction) Expected rate above IceCube background Hyper-K rate = 1/3 IceCube rate SASI still detectable 012) Counts/bin 89:;<6=>3; ("" +,)-./) '"" &"" ) %"" * $"" #""!"" 4000 IceCube 10 kpc 3000 e e 20 kpc Background 0 "#!!./,)0 1 "!!! "!*+,- (!! ) '!! %!! ) #!*+,- #!!!! "!! #!! $!! %!! &!! 234)*5467 Tamborra et al., PRL (2013). Tamborra et al., PRD (2014).

6 SASI Detection Perspectives SASI spiral mode Convective motions 20 M sun 11.2 M sun Time [ms] Time [ms] 27 M sun SN progenitor: Two SASI episodes with convective phase in between. 20 M sun SN progenitor: 11.2 M sun SN progenitor: One SASI episode. Large scale convection. SASI seems to occur for the heavier SN progenitors only. Tamborra, Hanke, Mueller, Janka, Raffelt, PRL (2013), PRD (2014). See also: Melson, Janka, Marek, ApJ (2015).

7 Power Spectrum of the Event Rate Power spectrum Power spectrum of the IceCube event rate in [100,300] ms M sun 20 M sun IceCube M sun Frequency [Hz] A peak appears at the SASI frequency of ~ 80 Hz for the 20 and 27 M Tamborra, Hanke, Mueller, Janka, Raffelt, PRL (2013). sun SN progenitors.

8 LESA Instability

9 Lepton Number Flux Evolution Lepton-number flux for the 11.2 M sun progenitor [(F e F e )/hf e F e i]. positive dipole direction Lepton-number emission asymmetry (LESA) is a large-scale feature with dipole character. Once the dipole develops, its direction remains stable. No-correlation with numerical grid. Tamborra, Hanke, Janka, Mueller, Raffelt, Marek, ApJ (2014).

10 Neutrino Energy Spectra Neutrino flux spectra in opposite LESA directions (11.2 Msun, t = 210 ms) Maximum lepton-number flux direction Minimum lepton-number flux direction e e e x e x During the accretion phase, fluxes strongly vary with the observer direction. Tamborra, Hanke, Janka, Mueller, Raffelt, Marek, ApJ (2014).

11 Lepton Number Flux Evolution Monopole, dipole and quadrupole of the lepton number flux Lepton Number Flux [ /s] z9.6 LS s20 LS 0.5 Time [s] m LS 0.5 rot Time [s] Time [s] s11 LS s LS 0.5 strange Time [s] m LS 0.5 artrot Time [s] Time [s] s27 LS s shen Time [s] l mode Time [s] z9.6 LS Radius [km] Y e Janka, Melson, Summa, ARNPS (2016). Tamborra, Hanke, Janka, Mueller, Raffelt, Marek, ApJ (2014).

12 SASI Dipole [10 52 erg/s] LESA Dipole [10 56 s 1 ] LESA-SASI Interference 5 27 M sun SASI SASI Time After Bounce [ms] 4 SASI SASI Time After Bounce [ms] 27 M sun, [170,260] ms SASI Dipole [10 52 erg/s] LESA Dipole [10 56 s 1 ] 5 20 M sun SASI Time After Bounce [ms] SASI Time After Bounce [ms] LESA dipole close to SASI plane No clear correlation between LESA and SASI. Interplay dependent on relative orientations of SASI plane and LESA dipole. Tamborra et al., ApJ (2014). Tamborra et al., PRD (2014). LESA dipole perp. to SASI plane

13 Implications of the LESA Phenomenon Nucleosynthesis in the neutrino heated ejecta: Considerable hemispheric asymmetry of the electron fraction in the neutrino ejecta. Neutron star kicks: Asymmetric neutrino emission imparts a recoil on the nascent NS. LESA responsible for angular momentum transfer, i.e. spin-up of the nascent NS. Neutrino-flavor conversions: LESA depends on hemispheric asymmetry of neutrino heating rates (modified by oscillations). Flavor conversions modify the n/p ratio in the context of nucleosynthesis. Directional neutrino-neutrino refraction index.

14 Consequences on Flavor Conversions

15 Neutrino Interactions Neutrinos in supernovae interact with matter and among each other. Understood phenomenon. all flavors e,µ, e,µ, Z fermion (p, n, e) e-flavor only e e W electron Neutrinos interact with neutrons, protons and electrons. Wolfenstein, PRD 17 (1978) 2369 We still need to learn a lot! ( ) ( ) Z ( ) ( ) interactions Non-linear phenomenon Pantaleone, PLB 287 (1992) 128

16 Simplified Picture of Flavor Conversions SN envelope Vacuum Earth Fast self-induced conversions? (flavor equilibration?) R Slow self-induced conversions (spectral splits) vacuum oscillations (Earth Matter Effect) -sphere Shock wave MSW m 2 resonance MSW m 2 resonance [not in scale]

17 Fast Pairwise Neutrino Conversions Flavor conversion (vacuum or MSW): e (p)! µ (p). Lepton flavor violation by mass and mixing. Pairwise flavor exchange by e (p)+ e (k)! µ (p)+ µ (k) scattering: e (p)+ µ (k)! µ (p)+ e (k) Can occur without masses/mixing. No net lepton flavor change. p m 2 Growth rate: 2GF (n e n e ) ' 6.42 m 1 vs.. 2E ' 0.5 km 1 Fast conversions Neutrino angular distributions crucial. Sawyer, PRD (2005), Sawyer, PRL (2016), Chakraborty et al., JCAP (2016).

18 PRL 118, (2017) P H Y S I C A L R E V I E W L E T T E R S week ending 13 JANUARY 2017 Fast Pairwise Conversion of Supernova Neutrinos: A Dispersion Relation Approach Frequency Ignacio Izaguirre, 1 Georg Raffelt, 1 and Irene Tamborra 2 1 Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, München, Germany 2 Niels Bohr International Academy, Niels Bohr Institute, Blegdamsvej 17, 2100 Copenhagen, Denmark (Received 10 October 2016; published 10 January 2017) Instabilities of flavor waves Instabilities ¼ of plasma waves cos( 1)=0.9 G 1 = 0.5 cos( 2)=0.3 G 2 = 0.5 (,k z) always real cos( 1)=+0.8 G 1 = 0.5 cos( 2)=-0.2 G 2 = 0.5 Complex k z for real in frequency gap -4 Stable Particle-like Frequency cos( 1)=0.9 G 1 =-0.5 cos( 2)=0.3 G 2 =+0.5 Complex for real k z Complex k z for real cos( 1)=+0.8 G 1 =-0.5 cos( 2)=-0.2 G 2 =+0.5 Complex for real k z in wavenumbergap Wave number k z Izaguirre, Raffelt, Tamborra, PRL (2017). Tachyon-like Wave number k z [Landau&Lifshitz, Vol. 10, Physical Kinetics, Chapter VI, Instability Theory]

19 Fast Pairwise Neutrino Conversions # km 20 km 30 km 40 km 50 km 100 km 200 km 400 km 30 Outward direction! Non-negligible inward neutrino flux may induce fast conversions. LESA may induce fast conversions. Flavor equipartition might occur close to neutrino decoupling region. Explosion affected? Existing investigations are simplified case studies. Further work needed. Tamborra et al., ApJ (2017). Izaguirre, Raffelt, Tamborra, PRL (2017). Capozzi et al

20 Conclusions Neutrinos play a fundamental role in supernovae. Intriguing neutrino features from 3D SN simulations. The SN neutrino signal can probe the nature of the hydrodynamical instability. Nu-nu interactions may potentially affect the explosion and LESA.

21 Thank you for your attention!