1. Discovery of Temporal Changes in the Torus around PSR B1509-58 Y. Yatsu, N. Kawai, T. Nakamori, & H. Nakajima Tokyo Institute of Technology 2009 July 8th 1

2. Contents of this talk Introduction Data Analysis and Results Discussion Conclusion 2009 July 8th 2

3. Temporal studies of PWNe We would like to find the temporal changes on the torus of PSR B1509-58 as seen in the Crab nebula. 2009 July 8th 3 - 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) Providing the information of plasma dynamics directly!

4. PSR B1509-58 Young and Energetic Pulsar D = 5.2 +/- 1.4 kpc P = 150 ms (  c  1700 yr) L spin = 1.8 x 10 37 ergs s -1 Surrounding Radio shell (MSH15-52) 2009 July 8th 4 We focused on the torus within 30” from the pulsar. PSR B1509-58 10 arcmin

5. 5 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: 30~60” Inner arc: ~30” South Jet Inner Ring R~10” 1 arcmin

6. Observations 2009 July 8th 6 We used archive data of four times monitoring observation. ObsIDDateExpTime 55342004,12,28 (T=0)50 ks 5535 T = 41 days43 ks 6116 T = 122 days48 ks 6117 T = 294 days46 ks

7. Region selection 2009 July 8th 7 v flow = c/3 (I = 50deg) In order to investigate the torus, the jet region was excluded. The funnel were divided into 80 sectors with a width of 0.5”. Jet Selected region Torus

8. Variations of radial profile 2009 July 8th 8 41 days 81 days 172 days 051015202530 Distance from the Pulsar [arcsec] Surface Brightness We searched moving features by using cross correlation function. We detected moving features on the torus running at 10.5 arcsec/yr outward from the pulsar ! We detected moving features on the torus running at 10.5 arcsec/yr outward from the pulsar ! Radial profile V app ~ 10.5 arcsec yr -1 (~ 0.86c for D=5.2 kpc) V app ~ 10.5 arcsec yr -1 (~ 0.86c for D=5.2 kpc)

9. Calculation of the moving velocity 2009 July 8th 9 Considering the superluminal motion effect, v ~ 0.65c (30° < i < 50°) is required for v app = 0.86c. i Torus i = 40° Apparent Velocity [c] 0 0.2 0.4 0.6 0.8 1.0 Velocity [c] 1.0 0.8 0.6 0.4 0.2 V app = 0.86c i = 30° i = 50°

10. What’s moving? (1) “Actual motion of the pulsar wind” Based on the brightness distribution of the torus (Pelling et al. 1987) V flow ≤ 0.6c (for i ≥ 30 deg) From the KC-model （ Kennnel & Coroniti 1984 ） … V flow = c/3(r TS /r) 2 ≤ c/3 2009 July 8th 10 It is difficult to explain the proper motion by the actual flow velocity of the pulsar wind.

11. What’s moving? (2) “Propagation of magneto-sonic wave” Velocity of the Fast-mode magneto-sonic wave 2009 July 8th 11 (Delaney et al. 2006) The Fast mod magneto-sonic wave can explain the observed proper motion.

12. 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. 2009 July 8th 12

13. Cross Correlation Function 2009 July 8th 13 CCF 41 days 81 days 172 days 051010 1515 2020 2525 3030 Surface Brightness Radial profile 0 2 4 6 8 10 Travel Distance [arcsec] CCF ΔT = 41 day ΔT = 81 day ΔT = 172 day CCF ΔT = 122 day

14. Inclination angle vs Flow velocity 2009 July 8th 14 i = 30°i = 50° i = 40°

15. 2009 July 8th 15