Particle Creation in GRB Central Region Strong Gravity and Electromagnetic Field Hyun Kyu Lee(...
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- Slide 1
- Particle Creation in GRB Central Region Strong Gravity and
Electromagnetic Field Hyun Kyu Lee( ) Hanyang University 2008
Nanjing GRB Conference June 23-27, 2008
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- Isotropic distribution Cosmic distances Isotropic energy Burst
duration T ~ ms 100 s Gamma Ray Bursts(GRB) I. Introduction
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- Central Region of GRB ?
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- Probing GRB Central Region
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- Black hole-Accretion disk Magnetic Braking II. A model for GRB
central engine
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- Rotational Energy of Kerr Black Hole
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- Simple Exercise: black hole-accretion disk(Poynting-flux
dominated flow) H.Kim & HKL, JKPS 42, S40(2003) turn-off
profile HKL, PRD 64, 043006(2001) rapidly declining LC
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- Ultra-Strong Magnetic Field GRB : B ~ 10^{15} G Magnetars :
SGR(Soft Gamma Repeaters, AXP(Anomalous X-Ray Pulsars) : B >
10^{14} G Radio Pulsars : B ~ 10^{12} G Magnetically dominated
system: E^2 B^2 < 0
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- Data vs. Magnetar model (Lyons et al. 2008) We expect a
relation between the pulsar initial spin period (P 0 ), dipole
field strength (B p ), luminosity (L) and the characteristic
timescale (T em ) for spin-down: L B p 2 / P 0 4 and T em P 0 2 / B
p 2 (overestimated if final rapid decay due to collapse) B p (G) P
0 (msec) 10 16 10 15 Spin period too short? Too faint vs. X-ray
plateau? B field too large or too brief? P. OBrien, 2008 Nanjing
GRB
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- III. Electromagnetic Vacuum Instability 3.1 QED e+ e- pair
creation Schwinger 1951 Electric Effect: E 2 B 2 > 0
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- 3.2 Fermion Production with Pauli Interaction Astrophysical
environment with storng magnetic field is magnetically dominant :
B^2 E^2 > 0 No Schwinger process Fermion with Magnetic Moment :
Pauli Interaction
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- Effective potential for uniform magnetic field Critical
magnetic field : HKL & Y. Yoon JHEP 03, 086(2007) Magnetic
Effect: B^2-E^2 > 0
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- HKL & Y. Yoon JHEP 03, 078(2007)
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- IV. Neutrino Production in GRB Central Region Neutrino: 1.
electrically neutral(beta decay) 2. massive(neutrino oscillation)
3. flavor mixing (neutrino oscillation) 4. Dirac or Majorana ? 5.
magnetic moment ? 6. physics beyond standard model
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- Theoretical and experimental bounds on neutrino magnetic moment
Critical magnetic field Slow process Continuous source of neutrinos
Production in mass eigenstate
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- Model for neutrino magnetic moment Neutrino production inside
fireball Neutrino emission in accretion torus Validity of effective
theory for strong magnetic field
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- V. e+e- pair production inside ergosphere Geometry around Kerr
black hole with mass m and angular momentum J=am Event horizon
Boundary of ergosphere Magnetically-dominated in preperation
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- On equator plane inside ergosphere 1. f < 0 : magnetically
dominated No Poyintng flux along the field lines
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- 2. non force-free equator: f > 0 pair creation of e + e - E
> E C accretion flow of particles in negative energy orbit.
(plasma effect is not included)
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- Power from ergo region
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- Out Looks New Laboratory Astrophysical Phenomena GRB, Magnetar
Compact Objects Neutron star ~ 10 km Black Hole ~ 1.5 km (horizon)
and Extreme Environment Strong Magnetic Field: B > 10^{15} G
Strong Gravity : horizon, ergosphere Particle creation:
Electromagnetic v acuum instability