CERNCERN ColloquiumColloquium Zoom, May 20, 2021 Core-Collapse Supernova Theory From Neutrino-driven Explosions to Observations Hans-ThomasHans-Thomas JankaJanka Max Planck Institute for Astrophysics Garching, Germany Contents 1. Introduction and background 2. Status of ab initio 3D core-collapse SN modeling of neutrino-driven explosion mechanism 3. Importance of pre-collapse progenitor asymmetries for SN explosions in 3D 4. Observational implications (neutrinos; NS kicks; Cas A, SN 1987A) 5. Open questions & perspectives 2 Stellar Collapse and Supernova Stages Supernova Collapse and Stellar 3 adapted from A. Burrows (1990) Neutrinos play a crucial role! They carry away the gravitational binding energy of the new-born NS: E = f*GM2/R ~ several 1053 erg. 4 Supernova 1987A Supernova 1987A (SN 1987A) 5 6 Problems & Questions ● Core collapse SN explosion mechanism(s) ● SN explosion properties; explosion asymmetries, mixing, gaseous remnant properties ● NS/BH formation paths and probabilities ● NS/BH birth masses, kicks, spins ● Neutrino and gravitational-wave signals ● Neutrino flavor oscillations, impact of non-standard physics, e.g. sterile neutrinos ● Heavy-element formation; what are the sites of the r-process(es)? ● What is the equation of state (EOS) of ultra-dense matter? 7 Onion-shell structure of pre-collapse star Star develops onion-shell H structure in sequence of nuclear burning stages He over millions of years C O Si Fe (layers not drawn to scale) 8 Onion-shell structure of pre-collapse star Star develops onion-shell H structure in sequence of nuclear burning stages He over millions of years C O Si Fe (layers not drawn to scale) 9 Gravitational instability of stellar core O Si O Fe 10 Core bounce at nuclear density O Accretion Si Fe Shock wave Proto-neutron star 11 Shock stagnation O Accretion Si Fe n, p Shock wave Proto-neutron star 12 Neutrino heating Accretion O Si ν ν ν n, p ν Shock wave Si Proto-neutron star 13 Shock revival O O O Ni ν ν n, p n, p, α ν ν Shock wave Proto-neutron star 14 Explosion and O nucleosynthesis O n, p, α, Ni ν (Zk,Nk) ν n, p ν Shock ν wave Neutrino- driven wind 15 ● ● Neutrino heatingNeutrino Neutrino coolingNeutrino Neutrino Heating and Cooling : : Hydrodynamic instabilities 16 16 See, e.g., Janka, ARNPS 62 (2012) 407 Critical Condition for Explosion Burrows & Goshy, ApJL (1993) 17 Universal CriticalUniversal Luminosity for for Luminosity Explosion Neutrino 2D 3D 3D 2D 18 18 Summa et al., ApJ 852 (2018) 28 Necessary Effort: Self-consistent "ab-initio" 3D neutrino-hydrodynamical simulations of neutrino-driven explosions 19 Predictions of Signals from SNe & NSs hydrodynamics of stellar plasma relativistic gravity (nuclear) EoS neutrino physics progenitor conditions dynamical models neutrinos nucleosynthesis LC, spectra gravitational waves explosion asymmetries, pulsar kicks explosion energies, remnant masses 20 2D and 3D Morphology (Images from Markus Rampp, RZG) 21 Progenitors: . Density Profiles High M Progenitor models: Woosley et al. (RMP 2002), Sukhbold & . Woosley (2014), Woosley & Heger (2015) Low M O'Connor & Ott, ApJ 730:70 (2011) 22 2D and 3D Electron-Capture SN Models Kitaura et al., A&A 450 (2006) 345; Wolff & Hillebrandt Janka et al., A&A 485 (2008) 199 ECSNe: (stiff) nuclear EoS Explosions of low-mass stars (~9 Msun) with O-Ne-Mg cores neutrino heating 50 Eexp ~ 10 erg = 0.1 bethe MNi ~ 0.003 Msun Gessner & Janka, ApJ 865 (2018) 61 23 3D Core-Collapse SN Explosion Models 9.6 Msun (zero-metallicity) progenitor (Heger 2010) Fe-core progenitor (Heger 2012) with ECSN-like density profile and explosion behavior. Melson et al., ApJL 801 (2015) L24 24 Nonradial Hydrodynamic Instabilities Convection SASI Convective Overturn Standing accretion shock instability NS NS Images: Tobias Melson Spiral SASI 25 Laboratory Astrophysics "SWASI" Instability as an analogue of SASI in the supernova core Foglizzo et al., PRL 108 (2012) 051103 Constraint of experiment: No convective activity 26 3D CCSN Explosion Model with Rotation 15 Msun rotating progenitor (Heger, Woosley & Spruit 2005) Explosion occurs for angular velocity of Fe-core of 0.5 rad/s, rotation period of ~12 seconds (several times faster than predicted for magnetized progenitor by Heger et al. 2005). Produces a neutron star with spin period of ~1‒2 ms. Janka, Melson & Summa, ARNPS 66 (2016); Summa et al., ApJ 852 (2018) 28 27 3D Core-Collapse SN Explosion Models 20 Msun (solar-metallicity) progenitor (Woosley & Heger 2007) Explore uncertain aspects of microphysics in neutrinospheric region: Example: strangeness contribution to nucleon spin, affecting axial-vector neutral-current scattering of neutrinos on nucleons We use: Currently favored ga = 1.26 theoretical & experimental s ga = ‒0.2 (HERMES, COMPASS) value: s ga ~ ‒0.1 Effective reduction of neutral-current neutrino-nucleon Melson et al., ApJL 808 (2015) L42 scattering by ~15% 28 Pre-collapse 3D Asymmetries in Progenitors 29 3D Core-Collapse SN Progenitor Model 18 Msun (solar-metallicity) progenitor (Heger 2015) 3D simulation of last 5 minutes of O-shell burning. During accelerating core contraction a quadrupolar (l=2) mode develops with convective Mach number of about 0.1. 151 s 270 s 294 s B. Müller, Viallet, Heger, & THJ, ApJ 833, 124 (2016) 30 3D Core-Collapse SN Explosion Model 18 Msun (solar-metallicity) progenitor (Heger 2015) 3D simulation of last 5 minutes of O-shell Onset of collapse Onset of collapse burning. During accelerating core contraction a quadrupolar (l=2) mode develops with convective Mach number of about 0.1. This fosters strong postshock convection and could thus reduces the criticial neutrino Si luminosity for explosion. Si 1.4 s post bounce 1.4 s post bounce δρ/ρ ~ Maconv B. Müller, PASA 33, 48 (2016); Müller, Melson, Heger & THJ, MNRAS 472, 491 (2017)31 Neon-oxygen-shell Merger in a 3D Pre-collapse Star of ~19 M sun Flash of Ne+O burning creates large-scale asymmetries in density, velocity, Si/Ne composition Radial velocity fluctuations Density variations Yadav, Müller et al., ApJ 890 (2020) 94 32 Explosion energy saturates at 10 saturates energy Explosion 3D M Explosionof~19 51 ergs after7 seconds ergs sun Star 33 33 R. Bollig et al., arXiv:2010.10506 3D Core-Collapse SN Explosion Models Garching/QUB/Monash (Melson+ ApJL 2015a,b; Müller 2016; Janka+ ARNPS 2016, Müller+ MNRAS 2017, Summa+ ApJ 2018, Glas+ ApJ 2019): 9.6, 20 Msun nonrotating progenitors (Heger 2012; Woosley & Heger 2007) 18 Msun nonrotating progenitor (Heger 2015) 15 Msun rotating progenitor (Heger, Woosley & Spuit 2005, modified rotation) 9.0 Msun nonrotating progenitor (Woosley & Heger 2015) ~19.0 Msun nonrotating progenitor (Sukhbold, Woosley, Heger 2018) Monash/QUB (Müller+ MNRAS 2018, Müller+MNRAS 2019): z9.6, s11.8, z12, s12.5 Msun nonrotating progenitors (Heger 2012) he2,8, he3.0, he3.5 Msun He binary stars, ultrastripped SN progenitors (Tauris 2017) 34 3D Core-Collapse SN Explosion Models Oak Ridge (Lentz+ ApJL 2015): 15 Msun nonrotating progenitor (Woosley & Heger 2007) Tokyo/Fukuoka (Takiwaki+ ApJ 2014): 11.2 Msun nonrotating progenitor more massive progenitors with rapid rotation (Woosley et al. 2002,2007) Caltech/NCSU/LSU/Perimeter (Roberts+ ApJ 2016; Ott+ ApJL 2018): 27 Msun nonrotating progenitor (Woosley et al. 2002), 15, 20, 40 Msun nonrotating progenitors (Woosley & Heger 2007) Princeton (Vartanyan+ MNRAS 2019, Burrows+ MNRAS 2020): 940 Msun suite of nonrot. progenitors (Woosley & Heger 2007, Sukhbold+2016) Modeling inputs and results differ in various aspects. 3D code comparison is missing and desirable 35 Status of Neutrino-driven Mechanism in 3D Supernova Models ● 3D modeling has reached mature stage. ● 3D differs from 2D in many aspects, explosions more difficult than in 2D. ● Neutrino-driven 3D explosions for progenitors between 9 and 40 Msun (with rotation, 3D progenitor perturbations, or slightly modified neutrino opacities) ● Explosion energy can take many seconds to saturate! 1051 erg possible! ● Progenitors are 1D, but composition-shell structure and initial progenitor-core asymmetries can be crucial for onset of explosion. ● 3D simulations may still need higher resolution for convergence. 36 Observational consequences Direct and indirect evidence for neutrino heating and hydrodynamic instabilities at the onset of stellar explosions: ● Neutrino signals (characteristic time dependencies) ● Gravitational-wave signals ● Neutron star kicks ● Asymmetric mass ejection & large-scale radial mixing ● Light curve shape, spectral features (elmagn. emission) ● Progenitor explosion remnant connection ● Nucleosynthesis 37 Detecting Core-Collapse SN Signals Superkamiokande IceCube VIRGO 38 Neutrino-emission features associated with multi-D flows ● SASI induced quasi-periodic modulations ● LESA: dipolar asymmetry of lepton-number emission 39 Neutrino-Signal Features During (Pre-)explosion Phase Janka H.-T., in: Handbook of Supernovae (2016); arXiv:1702.08713 40 3D Core-Collapse Models: Neutrino Signals 11.2, 20, 27 Msun progenitors (WHW 2002) SASI produces modulations of neutrino emission (and gravitational-wave signal). 27 Msun at 10 kpc Tamborra et al., PRL 111, 121104 (2013); PRD 90, 045032 (2014) 41 SASI Period Measures Shock Radius Evolution Measures Period Müller & THJ, ApJ 788 (2014) 82 42 42 LESA: A New Nonradial 3D Instability Nonradial 3D New A LESA: Lepton number flux: Lepton number ν e e minus anti- Dipole of asymmetry lepton-number emission (LESA) ν e heavy-lepton heavy-lepton neutrinos ν Total energy Total flux: e plus plus anti- ν e plus anisotropic convection