Discovery%20of%20Temporal%20Changes%20%20%20%20in%20the%20Torus%20around%20PSR%20B1509-58

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Discovery of Temporal Changes in the Torus
around PSR B1509-58

• Y. Yatsu, N. Kawai, T. Nakamori, H. Nakajima
• Tokyo Institute of Technology

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Contents of this talk

• Introduction
• Data Analysis and Results
• Discussion
• Conclusion

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Temporal studies of PWNe
Providing the information of plasma dynamics
directly!
- Crab nebula (Mori et al. 2004)
- Vela Pulsar (Pavlov et al. 2003)
- PSR B1509-58 (DeLaney et al. 2006)
- G11.2-0.3 (Roberts et al. 2003)
- PSR B0540-69 (DeLuca et al. 2007)

• We would like to find the temporal changes on the
  torus of PSR B1509-58 as seen in the Crab nebula.

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PSR B1509-58

• Young and Energetic Pulsar
• D 5.2 /- 1.4 kpc
• P 150 ms (tc 1700 yr)
• Lspin 1.8 x 1037 ergs s-1
• Surrounding Radio shell (MSH15-52)

PSR B1509-58
10 arcmin
We focused on the torus within 30 from the
pulsar.
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Very fine structures at the pulsar vicinity

• Nested tori
• -Inner arc
• -Outer arc
• Gaensler et al. 02
• DeLaney et al. 06
• Inner ring
• Yatsu et al. 09

Outer arc 3060
Inner arc 30
Inner Ring R10
South Jet
1 arcmin
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Observations
ObsID Date ExpTime
5534 2004,12,28 (T0) 50 ks
5535 T 41 days 43 ks
6116 T 122 days 48 ks
6117 T 294 days 46 ks

• We used archive data of
• four times monitoring observation.

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Region selection

• In order to investigate the torus, the jet
  region was excluded.
• The funnel were divided into
• 80 sectors with a width of 0.5.

vflow c/3 (I 50deg)
Selected region
Jet
Torus
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Variations of radial profile

• We searched moving features by using cross
  correlation function.

Radial profile
Vapp 10.5 arcsec yr -1 ( 0.86c for D5.2 kpc)
We detected moving features on the torus running
at 10.5 arcsec/yr outward from the pulsar !
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Calculation of the moving velocity

• Considering the superluminal motion effect,
• v 0.65c (30 lt i lt 50) is required for vapp
  0.86c.

i 40
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Whats moving? (1)

• Actual motion of the pulsar wind
• Based on the brightness distribution of the torus
• (Pelling et al. 1987)
• Vflow 0.6c (for i 30 deg)
• From the KC-model(Kennnel Coroniti 1984)
• Vflow c/3(rTS/r)2 c/3

It is difficult to explain the proper motion by
the actual flow velocity of the pulsar wind.
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Whats moving? (2)

• Propagation of magneto-sonic wave
• Velocity of the Fast-mode magneto-sonic wave

(Delaney et al. 2006)
The Fast mod magneto-sonic wave can explain the
observed proper motion.
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Summary

• We studied the temporal variation on the torus
  around PSR B1509-58 using Chandra.
• We found temporal changes on the torus
  propagating at 10.5 arcsec yr -1, analogous to
  the moving wisp as seen in the Crab nebula.
• The observed proper motion can be explained by
  the magnetosonic wave propagating at 0.7c .

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Cross Correlation Function
?T 41 day
CCF
?T 81 day
CCF
?T 122 day
CCF
?T 172 day
CCF
0 2 4 6
8 10 Travel Distance arcsec
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Inclination angle vs Flow velocity
i 30
i 50
i 40
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