High-energy gamma-ray and neutrino emission from the microquasar LSI +61 303

1. High-energy gamma-ray and neutrino emission from the microquasar LSI +61 303 Gustavo E. Romero, Instituto Argentino de Radioastronomía (IAR) Department of Astronomy and Geophysics, University of La Plata, Argentina Mariana Orellana Instituto Argentino de Radioastronomía (IAR) Department of Astronomy and Geophysics, University of La Plata, Argentina

2. from Massi et al. 2003 3EG J0241+6103 ? LSI +61 303 Massi et al. 2004 Primary star B0V Compact object ? Distance 2 kpc Porb 26.5 d e 0.72 ± 0.15 β apar ≥ 0.4 Phase of periastron 0.23 Paredes, J.M. [astroph:0501576] Orbital parameters: Casares et al. 2005

3. MAGIC detection of LSI +61 303

4. MAGIC detection of LSI +61 303 Albert et al. 2006

5. MAGIC detection of LSI +61 303

6. Up-dated SED Sidoli et al. 2006

7. Pure leptonic channels also result from the decay of secondary particles Secondary leptons Gamma-ray emission from MQs: ModelsLeptonic (Aharonian & Atoyan 1999; Bosch-Ramon et al. 2005, 2006; Dermer & Boettcher 2006, Bednarek 2006) Hadronic (Romero et al. 2003, 2005; Aharonian et al. 2006) In microquasars with high-mass stars, the stellar wind can provide a matter field for interactions with relativistic protons from the jet

8. Model: interactions between relativistic protons from the jet and cold protons form the wind Spherically symmetric wind Circular orbit Romero, G.E. et al 2003, A&A, 410, L1

9. Orbital phases for LS I +61 303 Massi 2004

10. Evolution of some parameters with the orbital phase with n=3.2 (Gregory & Neish 2002).

11. The model is dependent on the accretion rate and hence instrinsically time dependent Accretion rate onto the compact object

12. Some assumptions • Magnetic field is determined from equipartition with the kinetic energy of the jet, hence it is phase dependent. • Protons are accelerated by shocks in the inner jet to a power law of index p. Radiative losses are negligible so size constraints impose the upper limit on the proton energy. • There is a phenomenological “mixing factor” which accounts for the fraction of relativistic protons that interact with cold protons (typically fm~0.1).

13. Main parameters for the model

14. Photon-photon absorption due to the star Dubus 2006

15. Photon-photon absorption

16. Total photon-photon absorption

17. Light curve @ 200 GeV

18. Spectral energy distribution at different phases

19. Cascades close to the periastron passage qj=1

20. Synchroton emission from secondary pairs

21. Neutrino emission The estimated neutrino flux from LS I +61 303 on Earth is 4-5 muon-type neutrinos per km-squared per year (Christinasen, Orellana & Romero 2006). It could be detectable by IceCube . Ice top 1400 m Southern Hemisphere ICECUBE 2400 m

22. Conclusions Jet models where the jet power depends on a variable accretion rate will produce variable gamma-ray emission. In the case of LS I +61 303, opacity effects due to the radiation fields of the primary star and the circumstellar disk result in a maximum at f ~0.5. This is independent of the gamma-ray production mechanism. A hadronic model for the gamma-ray emission at high-energies cannot be ruled out by the current observations. Future neutrino observations of LSI +61 303 could be crucial to establish the nature of the radiative mechanism in the source.