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Information about kotake

Published on November 14, 2007

Author: Cinderella

Source: authorstream.com

超新星の爆発メカニズム と 重力波 Explosion mechanism of Core-Collapse Supernovae and Gravitational Waves:  超新星の爆発メカニズム と 重力波 Explosion mechanism of Core-Collapse Supernovae and Gravitational Waves 「超新星を舞台とする高エネルギー現象」東大理 2007年 2月            Kei Kotake  (National Astronomical Observatory of Japan) Slide2:  Section 1 : To explode, or not to explode, that is the question! :Current understanding of the Explosion mechanism Slide3:  ~20 years after the first simulations of successful neutrino heating mechanism (Wilson 1982) Wilson 1982 ~200km Iron core~1500km Slide4:  Releasable energy at explosion as neutrino 99% as kinetic energy 1% as radiation 0.01% Binding energy of neutron stars ・ One percent energy transfer to the neutrinos to the matter is required. ・ Numerical errors should be kept very small (within 1%?) ・ Supernova simulations has been of grand challenge of computational astrophysics. Energetics of neutrino heating mechanism Slide5:  (Wilson 1982) (Wilson 1982) Surface of iron core~1000km ~200km Looking back these 20 years!  Slide6:  Sophistications of microphysics in 1D simulations Looking back last two decades …..  Slide7:  No 1D models, can produce explosions. AGILE-BOLTZMANN (Oak –Ridge) Hydro: implicit GR Neutrino transport; 1D, Sn method (Mezzacappa & Bruenn 1993, Libendoefer et al. 2004) VERTEX (MPA) Hydro; explicit Newtonian Neutrino transport: VEF method (Rampp & Janka 2002) Yamada-Sumiyoshi code (Japan) Hydro: implicit GR Neutrino: Featrier method (Yamada ’97,99, Sumiyoshi et al.05) (Liebendoefer et al. 2003) Shock Radius Time VERTEX AGILE Shock stalls. Status of state-of-the-art 1D models Slide8:  Supernova Explosions are aspherical SN1987A Slide9:  What makes the asymmetry ? How the asymmetry affects the neutrino heating ? §1 Asymmetric Supernovae The problem is …. Slide10:  Roles of Convection Stalled shock 10 km Stellar radius Heating rate &cooling rate ~200km Cooling rate ~ R^{-6} Heating rate ~ R^{-2} PNS Cooing domintated Heating domintated ~ 100 km (Gain Radius) Slide11:  Convections rise the efficient of neutrino heating (Janka et al. 96) As a result of convections, neutrino heating is enhanced. Shedding time of neutrinos(s) Shock radius Slide12:  Treatment of Neutrino Transfer in Multi-D models Type I Type II PNS M Standing shock Lν 50km Treat only outside the Protoneutron star Full simulations ・ Gray transfer (Scheck et al. 03, Ohnishi et al. 05) ・2D ・Bruenn(1985) + sophistication ・Boltzmann (ray-by-ray) (2003年~) ・2D ・Bruenn (1985) ・FLD (2005年夏~) ・2D (Bruenn 1985) ・FLD、(2006年~) Courant condition is Not so severe Slide13:  Time evolution of shock in 1D and 2D models Buras et al. (’03,’06) Only with convections, it seems difficult to produce successful explosions. ・Boltzmann neutrino transfer (ray-by-ray) ・Promethius code ・Lattimer & Swesty EOS Slide14:  SASI = Standing Accretion-Shock Instability Blondin et al. (02,05) Foglizzo et al, 05 Ohnishi,KK,Yamada, (06) Blondin et al. (02,05) Blondin et al. found that adding the non-radial perturbation to the stalled shock wave, In their computations, no neutrino/heating are included. We are interested whether SASI really develops in more realistic situations. Slide15:  Basic equations Neutrino heating/cooling ・Contracting neutron star interior is replaced by the fixed boundary ・Changing the neutrino luminosity, we can systematically investigate the development of SASI. Bruenn (1985) Burrows et al. (01) Animation ! Slide16:  Ohnishi, KK, Yamda,06 Slide17:  SASI & Neutrino heating mechanism ・ Due to the SASI-operation, the heating regions can be enlarged. ・ However, input neutrino energy from the PNS may be higher. (Ohnishi, KK, Yamada 06) Slide18:  Can inelastic neutrino-nucleus scatterings lower the critical luminosities ? Ohnishi, KK, Yamada submitted PNS Fe -> n, p Haxton (1988) Preheating material at the moment of neutronization. This may be good because the Fe is dissociated before the shock-arrival. Bruenn & Haxton, (1991), Nu_e energy cannot be high for preheat the matter. Alternatively, they investigated that inelastic scatterings will help the neutrino reheating. But the result is negative due to the smaller radius at the shock-stall. The helium fraction is too small. But in the multiD case, does it work ? Slide19:  But please note that in the panels, the heating rate is made to be 10 times larger than Haxton (’88). Ohnishi, KK, Yamada submitted Inelastic scattering will not be a pivotal factor to enhance SASI. Slide20:  First 3D simulations of SASI Blondin & Mezzacappa (Nature, 2006) Slide21:  Continue’d Velocity fields in the equatorial plane Short summary: Effect of Hydrodynamic instabilities:  Short summary: Effect of Hydrodynamic instabilities ・ Convection enhances the neutrino heating,but only with convections, successful explosions may be difficult. (Buras et al. 2003) ・ Alternatively, SASI is expected to produce the large asymmetry, and  (Blondin et al. 03,05, Ohnishi, KK, Yamada. 2006) (Foglizzio et al. 06) ・could be the origin of the pulsar kick.  Blondin & Mezzacappa (2006), Iwakami et al. in prep with realistic SN simulations Another possible cause of “Asymmetry” :Rotation:  Another possible cause of “Asymmetry” :Rotation KK et al. 2003~ Slide24:  KK et al. (2003) Rotational Axis Equator 2D rotational core-collapse simulations Entropy contour Slide25:  3D view of rotating model Slide26:  To see the combined effects of rotation and the neutrino heating mechanism, we should tackle with the “Multidimensional neutrino transport problems” . : 2D Multi-energy Flux-Limited Diffusion with Magnetohydrodynamics                     Kotake, Ohnishi, Yamada, Sato In prep Slide27:  Code Tests in a static background Spatial distribution of antielectron neutrinos (with each energy bin) 0 km 80 km Antielectron neutrinos ω  =0.9MeV   ω  =110 MeV   Green :MonteCarlo sim Slide28:  Code Tests in a static background Spatial distribution of mu&tau neutrinos (with each energy bin) Mu & tau neutrinos Green:MonteCarlo sim Slide29:  Comparison with other full 1D calculations Liebendoerfer et al (’04) Liebendoerfer et al (’04) Shock wave Ye KK et al.(05) KK et al.(05) Our code can also produce the 1D Boltzman calculation. Slide30:  Hydrodynamical Simulations: Rotational Core-Collapse Intial Rotational Profile: 15 Msolar mass progenitor (Heger 00) T/|W| = 0.5 % Slide31:  Average energy of electron neutrino (MeV) Slide32:  Radiation flux of electron neutrino Radiation flux is preferentially towards the pole. Slide33:  Net heating rate (Heating – cooling rate) ☆Cooling region is narrower near the poles. ☆~20% enhancements of heating near the poles  than the equator. (MeV/nuc/s) Slide35:  To see clearly, Slide36:  Why convection occurs near equatorial plane ?? Criterion for (Solberg & Hoiland) Instability for rotating star Ledoux part j;specific ang.mom X:distance from rotational axis Specific angular momentum Yl Surface of PNS Slide37:  Why convection occurs near equatorial plane ?? Criterion for (Solberg & Hoiland) Instability for rotating star Ledoux part j;specific ang.mom X:distance from rotational axis Specific angular momentum Yl Surface of PNS ☆Convection in the vicinity of equatorial plane   might be the additional source for producing the   explosion in that direction. ☆Note that rotation-induced anisotropy illuminates   the matter near the pole preferentially. Slide38:  On-going calculations (no analysis done yet….) Slide41:  Burrows et al. 2005,6 Acoustic driven Supernovae ? (Explosion energy is not known (written)~10^{50}erg?? ) Acoustic Mechanism will work ?? Slide42:  PNS Analysis of Burrows et al’ calculations PNS Yoshida et al. (2007) performed an eigen mode analysis, in which a response of the PNS towards a given pressure perturbation on the surface of the PNS. Yoshida, Ohnishi, Yamada. (2007) astro-ph/0701643 Slide43:  G-mode excitations have typical frequencies of 200~500 Hz. Yoshida, et al. (2007) astro-ph/0701643 Input of the pressure perturbation Data from Numerical simulations by Ohnishi et al. (2006), There is a severe impedance mismatch between the typical frequency of SASI (~30Hz) and the excited g-modes (~200~500) Hz. Slide44:  Yoshida, et al. (2007) astro-ph/0701643 Mode energy is at most 10^{50} erg and even smaller. Slide45:  In Burrows et al. (2006), 10^{50} ergs.. Seems good… Slide46:  In Burrows et al. (2006), Slide47:  Show us Animation!! Left panel: Without g-mode Right panel: With g-mode (Delta P)/P = 10% G-mode induced calculations on surface of the PNS Ohnishi, KK, Yamada in prep Pressure perturbations are added to the surface of PNS by hand. Slide48:  Why “Asymmetric” supernovae ?? Although all the known microphysical process are included, spherical models cannot produce explosion. But still very important to investigate in details, (see e.g., Sonoda san, Iida san, ’s talk on Saturday!!)       Short summary of Section 3: Asymmetric Supernovae & Explosion mechanism Slide49:  “Asymmetric” supernovae Convection & Hydrodynamic instability ・Good for enhancing neutrino heating, however, only with it, successful explosions are not obtained.(Buras et al. 2005)   ・Importance of SASI (Blondin 2002, Fogglizo 2002, Ohnishi et al, 06) ・G-mode excitations inside PNS (Burrows et al,06) Rotation ・Rotation induced anisotopic neutrino radiation does really exist. (KK et al. 2003, Walder et al. 05) ・ Convective motions may be enhanced in the vicinity of the equatorial plane. (KK et al. in prep 2007) ・ Meanwhile, it is not yet know whether it really produces the explosion (KK et al. in progress) Magnetic fields: (See Bisnovatyi-Kogan, Moiseenko, Takiwaki, Sawai, talks tomorrow) Slide50:      Gravitational Waves from core-collapse supernovae Slide51:  When & How GWs are emitted from SNe ? Bounce origin Convection origin Neutrino origin Origins when At bounce Why ? (Cause of asphericity) Aspherical motions of inner core at bounce induced by rapid rotaion Aspherical motions of outer core after bounce Aspherical radiations of neutrinos (duration、~100 msec) After bounce (duration、~ 1 sec) After bounce (duration、~ 1 sec) Slide52:  Three + 1 typical waveforms Type III Type II Type I Longer interval Shorter interval Positive maximum Newtonian :Moenchmeyer et al. ’91,Yamada & Sato ’95 Zwerger et al. ’97,Rampp et al. ’98,Dimmelmeier et al. ’02 Fryer et al. 02,Ott et al. ’03,(2D, LS EOS), Mueller et al. ’03,Fryer et al. ’04 (3D), KK et al. (03,04),Ott et al, 04 Obergaulinger et al. (06) General Relativistic :Shibata(03),Shibata&Sekiguchi (04). Ott et al. (06) Slide53:  Detectablility SN @ 10 kpc KK et al.04 Slide54:  One concern of rotation-induced GWs is that,, the amplitude of GW is sharply depend on the initial rotation rateε Heger et al. 2000 Omega_0 = 4 rad/s Heger et al. 2005 Omega_0 = 0.3~0.05 rad/s due to the magnetic breaking 0.1 Slide55:  The GWs based on Heger 05 progenitor model KK et al. 04 Waveform amplitude Waveform:No characteristics amplitude:too weak to be detected by the laser interferometers in the next generation Slide56:  When & How GWs are emitted from SNe ? Bounce origin Convection origin Neutrino origin Name when At bounce Why ? (Cause of asphericity) Aspherical motions of inner core at bounce induced by rotaion Aspherical motions of outer coure after bounce Aspherical radiations of neutrinos (duration、~100 msec) After bounce (duration、~ 1 sec) After bounce (duration、~ 1 sec) Slide57:  Features of neutrino-originated GWs waveform KK et al. ApJ in press Slide58:  Spectrum of GW Neutrino-originated GWs dominate over the matter ones below~ 100 Hz, and may be the targets of LCGT. KK et al. ApJ in press Slide59:  Gravitational Wave Background: ,where Critical Density Energy density of GW Slide60:  SASI Induced Neutrino-Originated GWBs KK et al. ApJ in press will not be the obstacle to inflationary GWs Slide61:  Gravitational Waves from neutrinos inside PNS. The neutrino anisotropy seems to become larger. KK et al. prep Slide62:  Acoustic Driven Anisotropy & GW Ott et al. (2006) Slide63:  Summary of Gravitational Waves from Core-Collapse Supernovae ☆If the SNe are triggered by neutrino heatings, ・ Neutrino-originated GWs dominate over the matter-originated GWs below 100 Hz. ・Neutrino-originated GWs are expected to be larger than the matter-originated GWs later on.   ・ GWs from neutrinos are important because they may help us to understand the explosion mechanism. ☆If the SNe are triggered by the acoustic mechanism, ・the matter-originated GWs(>1kHz、~10^{-18}) will be emitted. ☆ Gravitational Wave Background (GWB) from SNe will not be an obstacle to the inflationary GWB. Slide64:  Collaborators: Shoichi Yamada(Waseda), Naofumi Ohnishi (Tohoku Univ.) Katsuhiko Sato (Tokyo Univ), Tomoya Takiwaki (Tokyo Univ), Hidetomo Sawai (Waseda), Yudai Suwa (Tokyo Univ.), Wakana Iwakami (Tohoku univ.) Thank you very much !

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