1. Integrated Profile Polarization : Observations and Speculations
Simon Johnston (ATNF, CSIRO)
Patrick Weltevrede, Aris Karastergiou, Dipanjan Mitra, Joel Weisberg

2. Outline High Edot pulsars The orthogonal rotator B0906-49
Why are they special and what do they tell us?
The orthogonal rotator B
Implications for beam models
Aside : The curious magnetars
Low Edot pulsars
Complexity and interpulse statistics
Beam model

3. High Edot pulsars Generalisations about their profiles
Highly polarized, no orthogonal mode jumps
Simpler profiles (?)
Wide doubles (?)
Emission heights
The case of PSR B
Beam model?
Links with slot gap high energy models?

4. Johnston & Weisberg 2006
8 pulsars: Common features
7/8 highly polarized – all doubles – 2nd component always brighter – reasonably symmetric - PA swing flat then steep – circular polarization generally only under 2nd component – widths ~40 degrees

5. Johnston & Weisberg 2006
6 pulsars: Common features
all highly polarized - all single – circular polarization – shallow swing of position angle – ~40 to ~100 degrees wide – flat spectral index

6. Linear polarization fraction versus Edot
Weltevrede & Johnston 2008
No orthogonal mode jumps. One mode dominates but this is split 50:50 between parallel and orthogonal modes!!
Abrupt transition between from low to high polarization states around Edot of

7. Polarization and the P-Pdot diagram
Harding et al. 2002
Weltevrede & Johnston 2008
Links with high energy slot-gap models??

8. Pulse width versus Edot
Orthogonal rotators
High Edot, wide beam single pole
Low Edot aligned rotators
Weltevrede & Johnston 2008

9. Emission Heights
Comparison of heights from (a) profile widths and (b) aberration ?
Weltevrede & Johnston 2008
Wide doubles have H90 > HPA which is evidence for U shaped emission height profile. Compare with slot gap models …
Harding et al. 2002

10. Wide doubles:
RVM fit
α=80, β=20.
JW06
Central component!!

11. PSR B0906-49 1.4 GHz 3.0 GHz RVM is well behaved!
Orthogonal rotator. Scattering affects , values.
8.4 GHz
Kramer & Johnston 2008

12. PSR B
Emission height 230 km. Emission seems to occur about 1/2 way to the last open field lines in both MP and IP beams!
Beams are patchy!
Well constrained. MP IP
Kramer & Johnston 2008

13. Aside :Two Radio Magnetars
Highly polarized. Good RVM fits (why?). Nearly aligned rotators? Or orthogonal?
Camilo et al. 2007, Kramer et al. 2007

14. Low Edot pulsars Profiles tend to be more complex
According to KJ07
PW cannot be convinced!
Polarization profiles are certainly more complex
Low polarization, orthogonal mode jumps, blended components, core components, smaller polar caps …
Magnetic/rotation axes align with time (Patrick’s talk later this week)
BUT orders of magnitude in Edot !!
The main measurable change is the polarization fraction

15. KJ07 beam model
High Edot Low Edot
Karastergiou & Johnston 2007

16. Patrick’s beam model
High Edot Low Edot

17. Beam models Karastergiou & Johnston 2007 Weltevrede 2008
High Edot pulsars have a single high emission height. This makes their profiles simple and highly polarized. Link to high energy
Low Edot pulsars have a large range of emission heights. This makes their profiles complex and mixes the polarization.
Weltevrede 2008
High Edot pulsars have a large range of emission heights. This blurs together features and makes them simple. Refraction in the magnetosphere can produce wide beams. Link to slot gaps models.

18. Beam models Karastergiou & Johnston 2007 Weltevrede 2008
High Edot pulsars have a single high emission height. This makes their profiles simple and highly polarized. Link to high energy
Low Edot pulsars have a large range of emission heights. This makes their profiles complex and mixes the polarization.
Weltevrede 2008
High Edot pulsars have a large range of emission heights. This blurs together features and makes them simple. Refraction in the magnetosphere can produce wide beams. Link to slot gaps models.
THIS IS FRUSTRATING !!

19. Summary Lots of interesting results
Rotation/velocity vectors aligned at birth
Rotation/magnetic axes align with time
High Edot = High polarization
High Edot can lead to very wide beams
What are the magnetars telling us?
Hanging it all together is the hard part!
Need to pursue the KJ07 model further
Refraction in the magnetosphere
GLAST will be deliver some great science but the (difficult to determine) geometry will be important
High quality low frequency profiles important