Vitrishchak V'M'

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Vitrishchak V.M. Gabuzda D.C. Mahmud
M. OSullivan S.
(c) http//hep.ph.liv.ac.uk/KM3NeT
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Circular polarization
Iij(ltLiLjgtltRiRjgt)/2
Vij(ltRiRjgt-ltLiLjgt)/2,
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Synchrotron emission
B
I?a ml (1- a)/(5/3-a)
f
?
??
Sazonov
mc 0 - C0(a) ctg(?) mc2/E? -C0(a) ctg(?)
1/2
3e B sin ?
f pitch-angle of the electrons
2pmc ?
? angle between the magnetic field vector and
the line of sight
In purely electron-positron plasma this remaining
term also cancels out
?
?mc2/E?
e/-
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U lt-gt V conversion
? Transversal magnetic field component needed
B
e-,e
z
? e- and e both contribute with the same sign
? Phase difference H2
x
tconst
y
Conversion depends on the angle between the plane
of the linear polarization being converted and
the converting magnetic field vector
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Parsec-scale circular polarization
? Typical degree from tenths of a percent up to
several percents. ? Most likely dominating
mechanism of generation - conversion from the
linearly polarized component while propagating
through the magnetized medium
? First CP measurements on the parsec scales
- Homan Wardle (1999), Homan, Attridge Wardle
(2001)
? MOJAVE (Monitoring of Jets in AGN with VLBI
Experiments) Homan Lister (2006). 34 sources
out of 133 showed CP signal on 15GHz in the core
regions. No correlation between the degree of CP
and more than 20 parameters of AGNs. ?
Vitrishchak Gabuzda (2007). 9 sources out of 41
showed the CP signal on 15GHz in the core
regions. 3 sources showed CP signal in the
extended jet.
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Sample CP map
GHz
Vitrishchak Gabuzda
Relative d, milliarcseconds
Relative a, milliarcseconds
mJy/BEAM
Levels
mJy/BEAM
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U lt-gt V conversion and CP sign
The sign of the circular polarization depends on
the projection of the angle between the
generating and converting magnetic field vectors

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Helical magnetic field structure
http//www.shao.ac.cn/tianwu/JC_AGN/agn.files/
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The simplest helical skin magnetic field model
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80
70
60
50
45
40
30
10
5
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Helical skin field
Helical skin field
CP sign and the projection of the angle between
the magnetic field vectors
90lt?lt180 Right helicity Large pitch-angles

0lt?lt90 Right helicity Small pitch-angles
-90lt?lt0 Left helicity Small pitch angles

-180lt?lt-90 Left helicity Large pitch-angles
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Faraday rotation
? Longitudal magnetic field component required
e
e-
z
? e- and e contribute with the opposite sign. No
rotation in purely pair-plasma
B
? Rotation direction depends on the magnetic
field direction
x
tconst
y
B
? ?0 RM ?2 RMconst ?ne B dl
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Rotation Measure gradient in helical fields
B
X
Left helicity
B
X
Right helicity
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Patrick Charlot
5 minutes, please
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Example 0735178 Left helicity
15GHz
FR gradient across jet
- field prevails
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Example 2251158 Right helicity
15???
Sorry for the terrible pictures
Spinesheath (-) B field
FR gradient across jet
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CP sign predictions
CP sign predictions According to the helical
field model
Probability of being very lucky 0.4
CP from Homan Wardle (1999), Homam Lister
(2006), Vitrishchak Gabuzda (2007) RM from
Taylor (1998, 2000), Zavala Taylor (2003),
Gabuzda et al. (2007)
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Conclusions
? The simplest helical skin magnetic field
model is considered. According to this model, the
CP sign is actually determined only by the
pitch-angle and helicity of the helical magnetic
field.
? Weve done the the pitch-angle and helicity
estimates for 8 sources with available CP
measurements, evident Faraday rotation gradient
and rather obvious linear polarization structure.
According to these estimates and the chosen
model, weve made the predictions of the CP sign
for these sources. In all 8 cases the predicted
CP sign was the same as the observed one.
? The complete agreement between the predictions
and the observations confirms the assumption of
the helical structure of the magnetic fields in
the AGN jets. Such structure can be formed by
winding up the seed B field by rotation of
central BH and accreation disk combined with jet
outflow.
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Mad things
Quadruple fields
Wormholes
Black hole
White hole