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1 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Morphological and spectral studies of the shell-type supernova remnants RX J1713.7-3946.

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Presentation on theme: "1 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Morphological and spectral studies of the shell-type supernova remnants RX J1713.7-3946."— Presentation transcript:

1 1 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Morphological and spectral studies of the shell-type supernova remnants RX J & RX J by H.E.S.S. M. Lemoine-Goumard, F. Aharonian, D. Berge, B. Degrange, D. Hauser, N. Komin, O. Reimer, U. Schwanke for the H.E.S.S. Collaboration

2 2 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources David Berge, HDGS July 2004 RX J Multi-Wavelength Observations Discovery: ROSAT All-Sky Survey (1996) X-ray emission mostly non-thermal Distance reestimated at 1kpc (Cassam-Chenai et al. and Fukui et al., 2004) CANGAROO observed TeV excess from western rim (Enomoto et al., 2000) Detection by H.E.S.S. in 2004 (Aharonian et al., 2004) Fukui et al. (2003) RA ROSAT (0.1-2 keV)XMM-Newton (2-10 keV) XMM + NANTEN

3 3 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources H.E.S.S. Observations in 2004 Observations with the full array of 4 telescopes 33 hours livetime ON source Zenith angles from 15 to 60 degrees Standard cuts are applied Shell of the remnant resolved Angular resolution < 0.1° → morphology resolved

4 4 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources RX J Spectrum Spectrum obtained with the 2004 dataset compatible with the one from 2003 Photon index of the remnant : ± 0.02 ± 0.15 Flux ~ 1 Crab Deviation from a pure power-law at high energy Extension of the spectrum up to 40 TeV → Particles accelerated up to ~100 TeV

5 5 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Spatially resolved spectra No significant change of the spectral shape from one region to another in TeV Significant changes of the spectral index observed in X-rays XMM-Newton Cassam-Chenai et al. H.E.S.S.

6 6 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources David Berge, DPG Tagung, März 2005 Energy dependence of the Morphology As opposed to X-rays, TeV morphology doesn’t change significantly with energy E < 0.6 TeV 0.6 < E < 1.4 TeV 1.4 TeV < E

7 7 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Correlation with X-rays Correlation coefficient between ASCA & HESS ~ 80%

8 8 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Primary population: electrons ? Need about 8 µG B field to match flux ratios Simplest electronic models don’t work well Simple one-zone model Electrons & protons injected with the same spectral shape Energy losses + escape of particles out of the shell taken into account B = 10 µG B = 8 µG B = 6 µG B = 10 µG B = 8 µG B = 6 µG Power-law index = 2.4 at injection level Power-law index = 2.2 at injection level

9 9 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Primary population: protons ? Spectral shape at the injection level: power-law + exponentional cut-off E cut = 120 TeV et index = 2.0 Energy injected = ergs Electron/proton ratio = 5× Magnetic field = 35 µ G & Density = 1.5 cm -3

10 10 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources RX J Multi-Wavelength Observations Discovery: ROSAT All-Sky Survey (1998) X-ray emission mostly non-thermal Distance still uncertain 200 pc - 1kpc Detected with H.E.S.S. in 2004 ROSAT all Sky Survey ASCA + CANGAROO contours

11 11 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources H.E.S.S. Observations in 2004 Observations from December 2004 to May hours livetime ON source Zenith angles between 20° and 50° Energy threshold : 250 GeV Results confirmed by an independent analysis Angular resolution < 0.1° → morphology resolved

12 12 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources RX J Spectrum Spectrum ranges from: 300 GeV up to 20 TeV Spectral index: 2.24 ± 0.05 stat ± 0.15 syst I (> 1TeV) = (15.2±0.7 stat ±3.20 syst )× cm -2 s -1 Flux and spectral index compatible with the results published in A&A Indication of deviation at high energy Extension of the spectrum up to 20 TeV → Particles accelerated up to ~100 TeV

13 13 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Correlation with X-rays Correlation coefficient between X-rays and HESS ~ 70% HESS ROSAT ASCA

14 14 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Primary population: electrons ? Leptonic process => Magnetic field ~ 7 µ G => Difficulty to confine electrons in the very thin shell resolved by HESS Nearby case (D ~ 200 pc)Distant case (D ~ 1 kpc)

15 15 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Primary population: protons ? Hadronic process => Magnetic field > 40 µ G to fit the X-ray data and suppress the IC-scattering component => Electron/proton ratio ~ 4 × Density ~ 2.2 cm -3 => Bubble mechanism needed to explain the absence of thermal X-rays (n < 0.1 cm - 3 Slane et al.) Nearby case (D ~ 200 pc)Distant case (D ~ 1 kpc)

16 16 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Morphological comparison between the 2 sources RX J RX J Morphology completely different Much thicker shell for RX J Width shell ~ 55% R remnant Width shell < 22.5% R remnant

17 17 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Spectral comparison between the 2 sources Almost the same flux Almost the same spectral index Indication of curvature at high energy

18 18 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources 2 shell-type supernova remnants established as γ -ray emitter and resolved for the first time in TeV X-ray morphology very similar to the γ -ray morphology observed with HESS First time ever spatially resolved spectral study of a gamma-ray source (RX J ) Flux ~ 1 Crab & Photon index ~ 2.2 Question of electron or hadron accelerator remains difficult to answer (=> solution should be given by HESS II & GLAST) Conclusions

19 19 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Column density in RX J fov D ~ 500 pc D ~ 1 kpc D ~ 1.5 kpc D ~ 2 kpc

20 20 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Correlation between CO and γ-rays in RX J fov

21 21 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Thickness of the whidth of RX J & RX J RX J width ~ 55% RX J width < 22.5 %

22 22 The Multi-Messenger Approach to Unidentified Gamma-Ray Sources Correlation between CO and γ-rays in RX J fov Azimuthal profile


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