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Magnetar-Driven Hypernovae Close Binary Progenitors Of Gamma Ray Bursts And Hypernovae Maxim Barkov MPI-K Heidelberg, Germany Space Research Institute, Russia Serguei Komissarov University of Leeds, UK 30/06/2011 HEPRO-III, Barcelona 1 Plan of this talk • Gamma-Ray-Bursts – very brief review, • Models of Central Engines, • Numerical simulations I: Magnetic flux, • Magnetic Unloading, • Realistic initial conditions, • Numerical simulations II: Collapsar model, • Common Envelop and X-Ray flares, • Fast Recycling of Neutron Star as Hypernova engine, • Conclusions 3030/06/2011/06/2011 HEPRO-III, Barcelona 2 I. Gamma-Ray-Bursts Discovery: Vela satellite (Klebesadel et al.1973); Konus satellite (Mazets et al. 1974); Cosmological origin: 1. Beppo-SAX satellite – X-ray afterglows (arc-minute resolution) , optical afterglows – redshift measurements – identification of host galaxies (Kulkarni et al. 1996, Metzger et al. 1997, etc)‏ 2. Compton observatory – isotropic distribution (Meegan et al. 1992); Supernova association of long duration GRBs: 1. Association with star-forming galaxies/regions of galaxies; 2. A few solid identifications with supernovae, SN 1998bw, SN 2003dh and others... 3. SN humps in light curves of optical afterglows. 52 4. High-velocity supernovae ( 30,000km/s) or hypernovae (10 erg). 30/06/2011 HEPRO-III, Barcelona 3 Spectral properties: Non-thermal spectrum from 0.1MeV to GeV: Bimodal distribution (two types of GRBs?): long duration GRBs short duration GRBs very long 30/06/2011 HEPRO-III, Barcelona duration GRBs4 Variability: • smooth fast rise + decay; • several peaks; • numerous peaks with substructure down to milliseconds Total power: assumption of isotropic emission Inferred high speed: Too high opacity to unless Lorentz factor > 100 30/06/2011 HEPRO-III, Barcelona 5 The possible scenario of GRB formation in close binary system with BH: 30/06/2011 HEPRO-III, Barcelona 7 II. Relativistic jet/pancake model of GRBs and afterglows: jet at birth (we are here) pancake later 30/06/2011 HEPRO-III, Barcelona 8 Merge of compact stars – origin of short duration GRBs? Paczynsky (1986); Goodman (1986); Eichler et al.(1989); Neutron star + Neutron star Neutron star + Black hole Black hole + compact disk White dwarf + Black hole Burst duration: 0.1s – 1.0s Released binding energy: 30/06/201130/06/2011 HEPRO-III, Barcelona 9 Collapsars– origin of long duration GRBs? Iron core collapses into a black hole: Woosley (1993)‏ “failed supernova”. Rotating envelope MacFadyen & Woosley (1999)‏ forms hyper-accreting disk Collapsing envelope Accretion disk Accretion shock The disk is fed by collapsing envelope. Burst duration > a few seconds 30/06/2011 HEPRO-III, Barcelona 10 Mechanisms for tapping the disk energy Neutrino heating Magnetic braking fireball MHD wind B B Eichler et al.(1989), Aloy et al.(2000) MacFadyen & Woosley (1999) Blandford & Payne (1982)‏ Nagataki et al.(2006), Birkl et al (2007) Proga et al. (2003)‏ Zalamea & Beloborodov (2008,2010) (???)‏ Fujimoto et al.(2006)‏ Mizuno et al.(2004) 3030/06/2011/06/2011 HEPRO-III, Barcelona 11 30/06/2011 HEPRO-III, Barcelona 12 III. Numerical simulations Setup (Barkov & Komissarov 2008a,b) black hole Uniform magnetization (Komissarov & Barkov 2009) M=3Msun R=4500km 27 28 -2 a=0.9 Y= 4x10 -4x10 Gcm Rotation: 2 3 l l0 sin minr / rc ,1 3 v rc=6.3x10 km 17 2 -1 B l0 = 10 cm s v v v • 2D axisymmetric GRMHD; v • Kerr-Schild metric; B • Realistic EOS; • Neutrino cooling; free fall outer boundary, • Starts at 1s from accretion R= 2.5x104 km (Bethe 1990) collapse onset. 30/06/201130/06/2011 HEPRO-III, Barcelona Lasts for < 1s 13 Free fall model of collapsing star (Bethe, 1990)‏ radial velocity: mass density: 1/ 2 t 1 M accretion rate: 1 M 0.1C1 M suns 1s 10M sun Gravity: gravitational field of Black Hole only (Kerr metric); no self-gravity; Microphysics: neutrino cooling ; realistic equation of state, (HELM, Timmes & Swesty, 2000); dissociation of nuclei (Ardeljan et al., 2005); Ideal Relativistic MHD - no physical resistivity (only numerical); 3030/06/2011/06/2011 HEPRO-III, Barcelona 14 Model:A unit length=4.5km 10 t=0.24s C1=9; Bp=3x10 G 3 log B /B log10 (g/cm ) log10 P/Pm 10 p magnetic field lines, and velocity vectors 3030/06/2011/06/2011 HEPRO-III, Barcelona 15 Model:A unit length=4.5km 10 t=0.31s C1=9; Bp=3x10 G 3 log10 (g/cm ) magnetic field lines, and velocity vectors 3030/06/2011/06/2011 HEPRO-III, Barcelona 16 Jets are powered mainly by the black hole via the Blandford-Znajek mechanism !! Model: C • No explosion if a=0; • Jets originate from the black hole; • ~90% of total magnetic flux is accumulated by the black hole; • Energy flux in the ouflow ~ energy flux through the horizon (disk contribution < 10%); • Theoretical BZ power: 50 2 2 51 1 EBZ 3.610 f aY27M2 0.4810 ergs 30/06/2011 HEPRO-III, Barcelona 17 1 17 2 1 M 0.15 M SUN s C1 3 l0 10 cm s B 0.31010G a 0.9 Pg log10() log10 Pm 30/06/2011 HEPRO-III, Barcelona 18 IV. Magnetic Unloading What is the condition for activation of the BZ-mechanism ? 1) MHD waves must be able to escape from the black hole ergosphere to infinity for the BZ-mechanism to operate, otherwise accretion is expected. or 2) The torque of magnetic lines from BH should be sufficient to stop 2 accretion EBZ / Mc 1(???) (Barkov & Komissarov 2008b) E 3.61050 f aY2 M 2 (Komissarov & Barkov 2009) BZ 27 2 a2 f a 2 2 30/06/2011 HEPRO-III, Barcelona 1 1 a 20 The disk accretion relaxes the explosion conditions. The MF lines’ shape reduces E / Mc2 1/10 the local accretion rate. BZ 30/06/2011 HEPRO-III, Barcelona 21 V. Realistic initial conditions • Strong magnetic field suppresses the differential rotation in the star (Spruit et. al., 2006). • Magnetic dynamo can’t generate a large magnetic flux, a relict magnetic field is necessary. (see observational evidences in Bychkov et al. 2009) • In close binary systems we could expect fast solid body rotation. • The most promising candidate for long GRBs is Wolf-Rayet stars. 30/06/201130/06/2011 HEPRO-III, Barcelona 22 Simple model: Barkov & Komissarov (2010) Rstar If l(r)<lcr then matter falling to BH directly If l(r)>lcr then l(r) matter goes to disk and after that to BH BH Agreement with model Shibata&Shapiro (2002) on level 1% 3030/06/2011/06/2011 HEPRO-III, Barcelona 23 Power low density distribution model r 3 30/06/2011 HEPRO-III, Barcelona 24 Realistic model Heger at el (2004) M=35 Msun, MWR=13 Msun 30/06/201130/06/2011 HEPRO-III, Barcelona 25 Realistic model Heger at el (2004) M=20 Msun, MWR=7 Msun M=35 Msun, MWR=13 Msun neutrino limit BZ limit 30/06/2011 HEPRO-III, Barcelona 26 VI. Numerical simulations II: Collapsar model Setup GR MHD 2D black hole M=10 Msun a=0.45-0.6 v Bethe’s B free fall model, T=17 s, C =23 v v 1 v Dipolar v magnetic field Initially solid body rotation B Uniform magnetization Barkov & Komissarov (2010) R=150000km 7 7 B0= 1.4x10 -8x10 G 30/06/2011 HEPRO-III, Barcelona 27 In some cases (30%) one side jets are formed. 30/06/2011 HEPRO-III, Barcelona 28 a=0.6 Ψ=3x1028 a=0.45 Ψ=6x1028 E 10 M V 170 sun kms1 kick 52 10 ergs M bh Model a Ψ28 B0,7 L51 dMBH /dt η A 0.6 1 1.4 - - - B 0.6 3 4.2 0.44 0.017 0.0144 C 0.45 6 8.4 1.04 0.012 0.049 30/06/2011 HEPRO-III, Barcelona 29 VII Common Envelop (CE): few Normal WRS seconds black hole spiralling And Black Hole < 1000 seconds disk formed 5000 seconds MBH left behind jets produced 30/06/2011 HEPRO-III, Barcelona 30 “Canonical” X-ray afterglow lightcurve (Swift) Zhang (2007) 0 1 5 10keV) – 2 3 (0.3 x F 4 10 log 1 2 3 4 5 log10(t/sec) • During CE stage a lot of angular momentum is transferred to the envelop of normal star. see for review • Accretion of the stellar core can (Taam & Sandquist 2000) give the main gamma ray burst. • BZ could work effectively with M 1 1 M 1.4 M suns low accretion rates. 10M sun t td 8000 s • Long accretion disk phase could be as long as 104 s, i.e. a feasible (Barkov & Komissarov 2010) explanation for X-Ray flashes. 30/06/201130/06/2011 HEPRO-III, Barcelona 31 VIII Fast Recycling of Neutron Star as Hypernova engine: Usov(1992), Thompson(1994), Thompson(2005), Bucciantini et al.(2006,2007,2008)‏, Komissarov & Barkov (2007), Barkov & Komissarov (2011) Rotational energy: Wind Power: (i) ultra-relativistic (ii) non-relativistic Gamma-Ray-Repeaters and Anomalous X-ray pulsars - isolated neutron stars with dipolar(?) magnetic field of 1014- 1015 G (magnetars); (Woods & Thompson, 2004) 30/06/2011 HEPRO-III, Barcelona 32 Possible scenario of GRB formation in close binary system with NS: 30/06/2011 HEPRO-III, Barcelona 33 NS in Common Envelop: few Red Giant seconds Neutron star spiralling And Neutron Star < 1000 seconds NS recycled, NS + WR Field generated 5000 seconds MBH left behind jets produced 30/06/2011 HEPRO-III, Barcelona 34 The accretion to NS: the sensitivity to parameters. Barkov & Komissarov (2011) Chevalier (1996) 30/06/2011 HEPRO-III, Barcelona 35 The accretion rate onto the NS in different models 30/06/2011 HEPRO-III, Barcelona 36 De Marco et al (2011) The NS penetration to the envelop of RG Chevalier (1996) 30/06/2011 HEPRO-III, Barcelona 37 NS with dipole field: P=4 ms B=1015 G 퐿 = 3.7 × 1049 erg/s The intensive accretion to NS of matter with accretion rate of 103 Msun/yr can lead to the generation of strong magnetic field.
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