radiation recoil velocity of a neutron star
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Radiation Recoil Velocity of a Neutron Star. Y. Kojima Hiroshima Univ. The 20 th Anniversary of JGRG & The 60 th Birthday of Prof. Nakamura & Prof. Maeda. JGRG20 at Kyoto Sept. 21-25 in 2010. Contents. High velocity of BH/NSs - PowerPoint PPT PresentationTRANSCRIPT
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Radiation Recoil Velocity of a Neutron Star
Y. Kojima Hiroshima Univ.
JGRG20 at Kyoto Sept. 21-25 in 2010
The 20th Anniversary of JGRG
&The 60th Birthday of Prof. Nakamura & Prof. Maeda
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ContentsHigh velocity of BH/NSs as a consequence of violent event Comment on high velocity of BH by GW radiation Models + recent observation Proper motion of pulsars/magnetars
Magnetic fields? Recoil velocity of a pulsar by EM radiation Shifted dipole Model ( Harrison &Tademaru 1975) Model of magnetic dipole + quadrupole radiation
(Y.K & Y. Kato 2010) Discussion
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Runaway Black Hole by GWVelocity by linear momentum radiation reaction
• Quadrupole +Octapole Gravitational Radiation
Bekenstein 1973 -…• BH Perturbation 1983 - …
Nakamura+Haugan+Sasaki+Oohara+Y.K.+….• Numerical Relativity 2006 -…
Baker et al …, Campanelli et al, +… Maximum velocity, ‘anti-kick’,…
cMcEMPv GWGW )/(/ 2
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Observational Evidence forHigh Velocity of BHs ?
e.g., Quasar E1821+643 @z=0.297 2100km/s Robinson et al 2010 SDSS J1054.35+345631.3 @z=0.272
3500km/s Shields et al 2009
• For super massive BH, GW recoil? • For stellar mass BH, some ambiguity with SN
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Proper Motion of PSRs
Proper motion by PSR timing methods,interferometersHelfand, Taylor & Manchester (1977) for 5 PSRsHobbs et al (2005) for 233 PSRs
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Velocity of PSR/MagnetarsProper motion Hobbs et al (2005)
Mean 3D velocity is 400km/s
Fast moving pulsarsPSR2224+45(Cordes+1993)B1508+55(Chatterjee+2005)
Upper limits for magnetarsAXP XTEJ1810-197 1E2259+586 SGR 1900+14
(Helfand+2007, Kaplan+ 2009…)
skmv /800
skmv /1000
skmv
skmv
skmv
/930
/1300
/210
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Kick Velocity of PulsarsProposed Mechanisms ( No References)
• Pre-natal scenario
Collapse of binary
• Natal scenario
Asymmetry of SN explosionNeutrinos/(Magneto-) Hydrodynamical waves
• Post-natal scenario
EM radiation and its recoil
skmRGMv /100)/( 2/1
Magnetic fields
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Kick Velocity caused by Magnetic Fields
Asymmetry of SN explosionNeutrinos/(Magneto-) Hydrodynamical wavesStrong field strength
EM-radiation and its recoil Field configuration
• When and how is the (strong) magnetic field generated? Fossil or dynamo?
• Upper limit for magnetars means no importance? Complicated?
GB 1510
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Strength & configuration of magnetic fields in newborn NS
Strong magnetic fields generated by dynamo
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Global Simulation of Dynamofor Fully Convective Rotating Stars
Saturated at
W. Dobler et. al., (2006) ApJ368, 336
2/133 )/(10 RGMt
NOT Neutron Star
Higher multipoles are generated.
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Strength & configuration of magnetic fields in newborn NS
Strong magnetic fields generated by dynamo (Thompson & Duncan 1993
Bonanno, Urpin & Belvedere 2006)
• For a fast rotator, strong ordered fields are generated.
• Maximum strength decreases, and higher mulitipole (small scale) fields dominate with decrease of initial spin.Almost dipole field in manetars, but dipole field + higher mulitipoles in PSRs
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Recoil Velocity by Radiation
Radiation of (GW/EM) waves• Energy is an incoherent sum
• In linear momentum radiation, interference is important
)( lmlmYAh
*
1
*)(cos)(/
)()(/
mllml
lmlmlmlmz
lmlmlmlm
AAC
YAYAddtdP
YAnYAddtPd
2
*)()(/
lm
lmlmlmlm
A
YAYAddtdEStrength
Configuration
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• Dipole shifted from center by s• Nonzero momentum by
up-down asymmetry of B
Off-center Dipole ModelHarrison &Tademaru (1975)ApJ 201, 447 ( Lai et al (2001) ApJ 549, 1111 )
Quadrupole moment
5
QP
RssQ
? Much larger Q
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Dipole and Quarupole Radiation
• Large quadrupole moment
• But, weak constraint in present slow rotating phase
Spindown is given by
RQQ B
0/ cQQ s
222)/( ll
l McL
,..., 21 QMM
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Model of Dipole plus Quradrupole Radiation
Paramters Strength Configuration
Magnetic radiation M(l,m) M(1,1), M(2,1),M(2,2)
Off-center DipoleM(1,1),M(2,1),E(1,1)
Q
Q, ,, 21
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Pure Dipole Dipole + Quadrupole
Global Structure of Closed Field Lines near Light Cylinder
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Symmetry of Radiation Partern
Poynting flux 2/ 0
+z
-z
Symmteric Asymmteric
Kick
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Radiation Loss and Evolution• Energy loss determines the spin evolution.
• Momentum loss determines the acceleration.
• Kinetic velocity is given by
M(1,1) M(2,1) M(2,2)
M(1,1) x M(2,1)
M
E
E
PdMLFIV rot
)/(
dt
dV
dt
d
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Efficient Configuration
Large momentum radiation Orthogonal dipole and quadrupole planes
Small M(2,2) radiation
Small inclination angle Almost axially symmetric quadrupole field
Maximum velocity at
icQ /
2/
skmmsPV i /)1/(930 2
22
iiP
M
E
E
PV rot
02
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SummaryKick velocity by rotating magnetic dipole
and quadrupole moments• Strong field is NOT necessary• Configuration is importantSlow velocity of magnetar with almost
diopleHigh velocity of PSR with large
quadrupole
• Or magnetic field is not relevant?
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Final Remaks• Porper motion is a relic of violent event• Direct observation by GWs, GRBs
LCGT soon!
We hope better understanding of the
relativistic astrophysics by the next anniversary of JGRG
meeting