Observations of SNR RX J0852.0-2644 with CANGAROO-II telescope

1. Observations of SNR RX J0852.0-2644 with CANGAROO-II telescope Kyoto, Dec., 16, 2003 H. Katagiri, R. Enomoto, M. Mori, L. Ksenofontov Institute for cosmic ray research (ICRR)

2. Introduction TeV  detection from SNRs SN1006 (CANGAROO) => e or p Cas-A (HEGRA) => p RX J1713.2-3946 (CANGAROO) => p RX J1713.2-3946 But claimed by Butt et al. and Reimer et al. … NANTEN supports our results (Fukui et al.) Inconclusive problem Need further evidence

3. SNR RX J0852.0-4622 2o ROSAT X-ray image (0.4<E<2.0keV) Maximum X-ray emission Vela SNR Flux (photons/sec/keV) 8o 1 5 10 Energy (keV)

4. Radio • Weak emissionSν at 1GHz =47±12Jy=>same as RXJ1713,SN1006. • Spectral index=0.400.15 Parkes 4.85GHz survey image(gray scale)

5. Molecular clouds CO integrated Intensity map NANTEN Vela region Vela SNR taken by NANTEN and soft X-ray image(gray scale) taken by ROSAT. Around Vela Molecular ridge taken by the Colombia University 1.2m millimeter-wave telescope.

6. EGRET Effected by Vela SNR and pulsar (2.5deg. distance) No point source in CANGAROO FOV

7. Profiles of RX J0852.0-4622 Ti line Column density from X-ray angular size Distance < 500pc Age 1000 yr • On the galactic plane => molecular clouds(l,b)=(266.2,-1.2) • Type II SNR • Density within SNR n<2.9×10-2D1-1/2 f--1/2 (g cm-2) low => stellar-wind cavity

8. CANGAROO observations • NW rim with maximum X-ray emission (,)=(132.25,-45.65) Minimum zenith angle 14.6o => Energy threshold 500GeV • Observation term 2002 and 2003 ON 97h OFF(background) 89h • Stereoscopic observation with 2 telescopes (2003) => under analysis CANGAROO-II 10m IACT in Australia

9. Procedure of analysis N.S.B. 1.Select clustered event =>remove N.S.B. 2.Arrival time of signal Almost the same time at shower event 3.Cut cloudy data 4.Cut low elevation data 5.Cut hot pixels

10. Image analysis In order to reject cosmic ray events as a noise Width Length Alpha Distance Source position Width and Length are the R.M.S. of the ADC counts on each axis.

11. Results Gamma-ray signal (ON-OFF) 8.0

12. Morphology Blue:our data Red:ASCA X-ray data Green:4850MHz continuum Consistent with X-ray and radio PSF Seems to be Point source

13. Synchrotron/inverse Compton model Source spectrum Differential flux of photons from the energy loss of electron (-function approximation) Electron energy Mass of the electron Spectral index Maximum accelerated energy of electrons Volume of emission region Distance from the earth Average time that an electron ( ) emits a photon ( )

14. Inverse Compton process Lorentz factor of electrons Cross section of Thomson scattering Energy density of CMB

15. Synchrotron process

16. One-zone model: • EGRET: • Diffuse emission • Upper limits (counts + 2)

17. “Simple” Two-zone model:

18. Difficulty in two-zone model

19. Two-zone model: X-ray TeV (Aharonian, Atoyan, and Kifune) Too many parameters!!! Need Chandra, XMM-newton results (filaments ?) and more exact discussion (escape time, energy loss process)

20. model (Naito-Takahara model) to

21. Intensity of protons Differential cross section Low energy: isobar model High energy: scaling model

22. Fitting parameters Data CANGAROO EGRET diffuse (upper limits) Best fit

23. Best fit model :solid angle of the observed part

24. Summary • Our data strongly favour gamma rays from neutral pions and low flux from synchrotron/inverse Compton. • NANTEN data will give us more physics. • Fine structure allow two-zone model.Chandra and XMM-newton resutlts are needed.

25. Check of approximation RX J1713.2-3946 Full calculation Delta function approximation Factor is 1.5, but it does not change conclusion.