Understanding the periodicities in radio and GeV emission from LS I+61303

Abstract

Accretion models predict two ejections along the eccentric orbit of LS I +61 303: one major ejection at periastron and a second, lower ejection towards apastron. We develop a physical model for LS I +61 303 in which relativistic electrons are ejected twice along the orbit. The ejecta form a conical jet that is precessing with P2. The jet radiates in the radio band by the synchrotron process and the jet radiates in the GeV energy band by the external inverse Compton and synchrotron self-Compton processes. We compare the output fluxes of our physical model with two available large archives: OVRO radio and Fermi Large Area Telescope (LAT) GeV observations, the two databases overlapping for five years. The larger ejection around periastron passage results in a slower jet, and severe inverse Compton losses result in the jet also being short. While large gamma-ray emission is produced, there is only negligible radio emission. Our results are that the periastron jet has a length of 3.0 10^6 rs and a velocity beta ~ 0.006, whereas the jet at apastron has a length of 6.3 10^7 rs and beta ~ 0.5.

A&A in press, 11 pages, 7 figures

References in corpus (8)

• Gamma-ray binaries: pulsars in disguise ?
• Accretion vs colliding wind models for the gamma-ray binary LS I +61 303: an assessment
• INTEGRAL and XMM-Newton observations of LSI +61 303
• VLBA images of the precessing jet of LSI+61303
• Long-term periodicity in LSI+61303 as beat frequency between orbital and precessional rate
• Evidence of coupling between the thermal and nonthermal emission in the gamma-ray binary LS I +61 303
• Discovery of a periodical apoastron GeV peak in LS I +61°303
• Long-term OVRO monitoring of LSI+61303: confirmation of the two close periodicities

Cited by in corpus (5)

• Revisiting LS I +61 303 with VLBI astrometry
• Evidence for periodic accretion-ejection in LSI+61303
• Radio QPO in the $\gamma$-ray-loud X-ray binary LS I +61${}^{\circ }$303
• A Precessing Jet Scenario for the Multi-Wavelength Long-Term Modulation of LS I +61${}^{\circ }$303
• Owens Valley Radio Observatory monitoring of LS I +61°303 completes three cycles of the super-orbital modulation