Particle Creation in GRB Central Region Strong Gravity and Electromagnetic Field Hyun Kyu Lee(...
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Particle Creation in GRB Central Region Strong Gravity and Electromagnetic Field Hyun Kyu Lee( 李李李 ) Hanyang University 2008 Nanjing GRB Conference June 23-27, 2008
Particle Creation in GRB Central Region Strong Gravity and Electromagnetic Field Hyun Kyu Lee( 李賢揆 ) Hanyang University 2008 Nanjing GRB Conference June
Particle Creation in GRB Central Region Strong Gravity and
Electromagnetic Field Hyun Kyu Lee( ) Hanyang University 2008
Nanjing GRB Conference June 23-27, 2008
Slide 2
Isotropic distribution Cosmic distances Isotropic energy Burst
duration T ~ ms 100 s Gamma Ray Bursts(GRB) I. Introduction
Slide 3
Central Region of GRB ?
Slide 4
Probing GRB Central Region
Slide 5
Black hole-Accretion disk Magnetic Braking II. A model for GRB
central engine
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
Slide 9
Slide 10
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
Slide 11
III. Electromagnetic Vacuum Instability 3.1 QED e+ e- pair
creation Schwinger 1951 Electric Effect: E 2 B 2 > 0
Slide 12
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
Slide 13
Effective potential for uniform magnetic field Critical
magnetic field : HKL & Y. Yoon JHEP 03, 086(2007) Magnetic
Effect: B^2-E^2 > 0
Slide 14
HKL & Y. Yoon JHEP 03, 078(2007)
Slide 15
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
Slide 16
Theoretical and experimental bounds on neutrino magnetic moment
Critical magnetic field Slow process Continuous source of neutrinos
Production in mass eigenstate
Slide 17
Model for neutrino magnetic moment Neutrino production inside
fireball Neutrino emission in accretion torus Validity of effective
theory for strong magnetic field
Slide 18
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
Slide 19
On equator plane inside ergosphere 1. f < 0 : magnetically
dominated No Poyintng flux along the field lines
Slide 20
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)
Slide 21
Power from ergo region
Slide 22
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