1. On the Emission Site of Gamma Rays from Pulsars Hsiang-Kuang Chang and Cheng Ho 徐佩君清華大學天文研究所

2. Gamma-Ray Pulsars

3. Their spectra (Thompson et al. 1999)

4. Models Polar-cap Outer-gap (Harding 2000)

5. Power-law Spectra (Nolan et al. 1996)

6. Photon Indices

7. a steady cooling population of charged particles  Synchrotron radiation P=2 → Γ ＝ 3/2  Curvature radiation P=4 → Γ ＝ 5/3 Assumption

8. Method radiationcurvaturesynchrotron energy loss rate characteristic energy of the emission cooling time scale dynamical time scale

9.  The distance of the inferred emission site from the stellar center curvature radiation synchrotron radiation Requiring that at the emission site

10. Bending Energy (Eb) of PSR B1509-58 (Matz et al. 1994) ~ 50 keV

11. Eb of Vela (Strickman et al. 1996) 10~70 MeV

12. Eb of PSR B1706-44 (Ray, Harding & Strickman 1999) 10 keV ~ 30 MeV

13. Eb of PSR B1951+32 (Chang & Ho 1997; Chang & Guo 2000) 70 keV ~ 3 MeV

14. Eb of Geminga (Mayer-Hasselwander et al. 1994)(Jackson et al. 2002) 10~30 MeV

15. Eb of PSR B1055-52 (Thompson et al. 1999) 1 keV ~ 70 MeV

16. Determining the emission site (H-K Chang)

17. Result

18. Discussion Under the assumption that the gamma-ray emission comes from a steady cooling population of charged particles, the synchrotron radiation in outer magnetospheres as the emission mechanism is consistent with the spectral behavior of most gamma-ray pulsars. Exception: Crab pulsar, PSR B1509-58 The inverse Compton scattering is not considered in this method

19. Reference Peter Meszaros, 1992, The University of Chicago Press, “ High-Energy Radiation from Magnetized Neutron Stars ” Harding A. K., 2000, arXiv:astro-ph/0012268 George B. Rybicki, Alan P. Lightman, New York :Wiley,c1979. “ Radiative processes in astrophysics ” Chang H.-K., Guo T.-F., 2000, Chinese Journal of Physics, 38, 429 Chang H.-K., Ho C., 1997, ApJ, 479, L125 Jackson M. S. et al., 2002, ApJ, 578,935 Matz S. M. et al., 1994, ApJ, 434, 288 Mayer-Hasselwander H. A. et al., 1994, ApJ, 421, 276 Nolan P. L. et al., 1996, A&AS, 120, C61 Ray A., Harding A. K., Strickman M., 1999, ApJ, 513, 919 Strickman M. S. et al., 1996, ApJ, 460, 735 Thompson D. J. et al., 1999, ApJ, 516, 297

20. Thank you !