I. Gamma-ray binary, LS5039 II. GeV break problem III. Model with a soft X-ray source IV. Summary
Gamma-rays vary with orbital period Gamma-rays are detected as flares Candidate: AGL J2241+4454 (HD 215227(Be)) Cyg X-15.6d3x10^12cmO + BH Cyg X-34.8hr5x10^11cmWR + ??(BH or NS) ObjectsPeriodScaleConsists of … LS 50393.9d5x10^12cmO + ?? (BH or NS) LS I +61° 30326d10^13cmBe + ?? PSR B1259-633.4yr10^14cmBe + NS HESS J0632+057 320d10^14cmBe + ?? 1FGL J1018.6-5856 16d10^13cmO + ??
A. A. Abdo, et al., 2009, ApJL, 706, 56 F. Aharonian, et al., 2006, A&A, 460, 743 T. Takahashi, et al., 2009, ApJ, 697, 592 Suzaku Fermi HESS ・ TeV & GeV anticorrelate ・ TeV & X correlate ・ spectral break at ~1 GeV Fermi Suzaku Photon energy (eV) Phase-averaged spectra Orbital phase Light curves MS superiorinferior HESS SUPC INFC SUPC
If electrons scatter off stellar photons, the break is not reproduced Assume that the break is due to γγ absorption Typical energy of absorbed photons: tens of GeV We assume that electrons scatter off 100 eV photons 0.1G 3G Yamaguchi & Takahara, 2010, ApJ, 717, 85 If 10 times of this Therefore,
Optical depth τ > 1 No influence on Suzaku data Energy of e± < 1TeV near 100 eV source Magnetic field: a parameter we calculate cascade with 100eV photons, and with stellar photons far from it 100eV source Requirement for 100eV source Electron injection injection site γ-ray
GeV break is reproduced X-ray spectral index matches when B=100G X-ray flux matches when B=300G No orbital variation in X-ray and GeV band B = 100 G B = 300 G
Strong magnetic field U ph (100 eV) > U ph (stellar photon) → IC cooling time shorter → the number of e± smaller → strong B is required to fit with obs. No variation in GeV & X-ray band e± scatter off photons near CS → direction to CS independent of phase → No modulation in GeV band No change in the number of electrons → No modulation in X-ray band Superior conjunction Inferior conjunction CS O star CS O star
For LS 5039, the observed break energy in GeV band is 3 GeV, different from expected one So we introduce 100eV photon source spectral break is reproduced X-ray flux is reproduced when B = 300 G X-ray & GeV have no variation (by isotropy of 100eV source) This is a possible model! With 100eV source, we introduce orbital variation of injection (as in Owocki et al. 2010, proceeding) Without 100eV source, we regard GeV cutoff as high energy cutoff of injected e± prospect