Neutrinos from explosive astrophysical objects Yudai Suwa Yukawa - PowerPoint PPT Presentation

公募研究「爆発的天体現象とニュートリノ輸送」 Neutrinos from explosive astrophysical objects Yudai Suwa 諏訪 雄大 Yukawa Institute for Theoretical Physics, Kyoto University 京都大学 基礎物理学研究所 Public solicited research

Supernovae are stellar deaths Baade & Zwicky 1934 2 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

A supernova (c)ASAS-SN project

Key observables characterizing supernovae 10 51 erg = 10 44 J = 6.2x10 53 GeV M ⦿ (solar mass) = 2.0x10 30 kg = 1.1x10 57 GeV/c 2 Explosion energy: ~10 51 erg measured by fj tting SN light curves Ejecta mass: ~M ⦿ (i.e. time evolution of brightness) Ni mass: ~0.1M ⦿ measured by Neutron star mass: ~1 - 2 M ⦿ binary systems fj nal goal of fj rst-principle ( ab initio ) simulations 4 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

Fe Standard scenario of core-collapse supernovae Final phase of stellar Neutron star formation Neutrinosphere formation evolution (core bounce ） （ neutrino trapping ） Neutron Fe Neutrinosphere Star Si O,Ne,Mg C+O HeH ρ c ~10 14 g cm -3 ρ c ~10 11 g cm -3 ρ c ~10 9 g cm -3 shock stall shock revival Supernova! HOW? NS Si O,Ne,Mg C+O HeH 5 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

Current paradigm: neutrino-heating mechanism heating region shock cooling region absorption neutron staremission A CCSN emits O (10 58 ) of neutrinos with O (10) MeV. Neutrinos transfer energy Most of them are just escaping from the system (cooling) Part of them are absorbed in outer layer (heating) Heating overwhelms cooling in heating ( gain ) region 6 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

Physical ingredients ALL known interactions are involving and playing important roles Strong Weak - nuclear equation of state - neutrino interactions σ ν ~10 -44 cm 2 (E ν /m e c 2 ) 2 - structure of neutron stars R NS ~10-15 km - ~99% of energy is emitted by ν ’s max(M NS )> 2 M ⊙ - cooling of proto-neutron star - nucleosynthesis - heating of postshock material Electromagnetic Gravitational - energy budget - Coulomb collision of p and e E G ~3.1x10 53 erg(M/1.4M ⊙ ) 2 (R/10km) -1 - fj nal remnants are ~0.17M ⊙ c 2 pulsars ( B~10 12 G) - inducing core collapse magnetars ( B~10 14-15 G) - making general relativistic objects magnetic fj elds a fg ect dynamics (NS/BH) 7 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

What do simulations solve? Numerical Simulations Hydrodynamic Neutrino Boltzmann equations equation d ρ Solve dt + ρ ∇ · v = 0 , � � d ln ρ � � � 1 − µ 2 � ∂ f cdt + µ ∂ f df + 3 v + 1 ∂ r + µ simultaneously cdt cr r ∂ µ ρ d v � � d ln ρ � � + 3 v − v E ∂ f dt = −∇ P − ρ ∇ Φ , µ 2 + cdt cr cr ∂ E E 2 de ∗ e ∗ + P �� � � = j (1 − f ) − χ f + dt + ∇ · = − ρ v · ∇ Φ + Q E , v c ( hc ) 3 � � � � dY e Rf ′ dµ ′ − f � 1 − f ′ � dµ ′ (1 − f ) R . × dt = Q N , △ Φ = 4 π G ρ , ρ : density , v : velocity , P : pressure , Φ : grav. f : neut. dist. func, µ : cos θ , E : neut. energy, potential, e * : total energy, Y e : elect. frac., j : emissivity, χ : absorptivity, R : scatt. Q : neutrino terms kernel 8 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

1D SN simulations fail to explode Rammp & Janka 00 Liebendörfer+ 01 shock shock By including all available physics to simulations, we concluded that the explosion cannot be obtained in 1D! (There are a few exceptions; 8.8M ⊙ , 9.6M ⊙ ) Thompson+ 03 Sumiyoshi+ 05 shock shock 9 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

Neutrino-driven explosion in multi-D simulation We now have exploding models driven by neutrino heating with 2D/3D simulations 2D (maximum) 2D (minimum) 1D The neutrino heating rate is greatly ampli fj ed by multi-D hydrodynamic e fg ects Suwa+ PASJ, 62 , L49 (2010) (2D) ApJ, 738 , 165 (2011) convection ApJ, 764 , 99 (2013) PASJ, 66 , L1 (2014) standing-accretion shock MNRAS, 454 , 3073 (2015) instability ApJ, 816 , 43 (2016) 10 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

Dimensionality and neutrino transfer ※ grid-based codes only, not completed Only the simulations here can judge the neutrino-driven explosion Dimension Iwakami+, 08 Takiwaki, Kotake, & Suwa, 12 Blondin+, 07 3D Mikami+, 08 Hanke+, 13 Scheidegger+, 08 Fernandez+, 10 Lentz+, 15 Nordhaus+, 10 Endeve+, 10 Hanke+, 12 Müller, 15 Couch, 13 Handy+, 14 2D Kotake+, 03 Burrows+, 06 Yamada & Sato, 94 (axial-sym.) Buras+, 06 Blondin & Mezzacappa, 03 Ohnishi+, 06 Ott+, 08 Obergaulinger+, 06 Murphy+, 08 Suwa+, 10 Takiwaki+, 09 Müller+, 12 Sekiguchi+, 11 Bruenn+, 13 Obergaulinger+,14 Pan+, 16 O’Connor+, 15 1D Rampp & Janka, 00 (spherical-sym.) Liebendörfer+, 01 Thompson+, 03 Sumiyoshi+, 05 O’Connor+, 13 Spectral transport cooling only Adiabatic or Neutrino Treatment �������������-���.�����/�����.-������ �.��������.-� /�/ heat by hand 11 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

3D simulation with spectral neutrino transfer [Takiwaki, Kotake, & Suwa, ApJ, 749 , 98 (2012); ApJ, 786 , 83 (2014); MNRAS, 461 , L112 (2016)] M ZAMS =11.2 M ⊙ 384(r)x128( θ )x256( φ )x20(E ν ) XT4 T2K-Tsukuba K computer 12 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

Note: there are problems Explosion energy of simulations ( O(10 49-50 ) erg ) is much smaller than observational values ( O(10 51 ) erg ) Results from di fg erent groups are contradictory We need still more e fg orts to understand supernova mechanism Key observables characterizing supernovae 10 51 erg = 10 44 J = 6.2x10 53 GeV M ⦿ (solar mass) = 2.0x10 30 kg = 1.1x10 57 GeV/c 2 Explosion energy: ~10 51 erg measured by fj tting SN light curves Ejecta mass: ~M ⦿ (i.e. time evolution of brightness) Ni mass: ~0.1M ⦿ measured by Neutron star mass: ~1 - 2 M ⦿ binary systems fj nal goal of fj rst-principle ( ab initio ) simulations 4 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15 13 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

Possible solution: extension of neutrino transfer eq. L [ f ]= C [ f ] Liouville operator Collision operator (number conservation in phase space) (particle interactions) Relativistic correction 
 Collision operator used in simulations is truncated up to O(v/c) and higher order terms are not taken into account, which may change neutrino spectrum and heating rate. Quantum correction 
 Liouville operator is based on classical particle picture. Quantum e fg ects would introduce additional terms. Related to neutrino oscillation and chiral anomaly. 14 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15

Summary Neutrinos play essential roles in supernova explosions None of modern simulations have obtained realistic explosions so far We might be missing something important Two possibilities in neutrino transfer equation relativistic correction quantum correction 15 29/11/2016 Yudai Suwa @ Neutrino Frontier Workshop 2016 /15