Revisiting LS I +61 303 with VLBI astrometry

Abstract

We conducted multi-epoch VLBA phase reference observations of LS I +61 303 in order to study its precessing radio jet. Compared to similar observations in 2006, we find that the observed elliptical trajectory of emission at 8.4 GHz repeats after the 9-year gap. The accurate alignment of the emission patterns yields a precession period of 26.926 +- 0.005 d, which is consistent with that determined by Lomb-Scargle analysis of the radio light curve. We analytically model the projection on the sky plane of the peak position of a precessing, synchrotron-emitting jet, which traces an elliptical trajectory on the sky. Comparing the simulation with the VLBA astrometry we improve our knowledge of the geometry of the system.We measure the LS I +61 303 absolute proper motion to be -0.150 +- 0.006 mas/yr eastward and -0.264 +- 0.006 mas/yr northward. Removing Galactic rotation, this reveals a small, < 20 km/s, non-circular motion, which indicates a very low kick velocity when the black hole was formed.

10 pages, 10 Figures, 1 Table, MNRAS accepted 2017 November 19

References in corpus (8)

• Gaia Data Release 1: Catalogue validation
• A Parallax Distance to the Microquasar GRS 1915+105 and a Revised Estimate of its Black Hole Mass
• Investigating stellar-mass black hole kicks
• Accretion vs colliding wind models for the gamma-ray binary LS I +61 303: an assessment
• Periodic very high energy gamma-ray emission from LS I +61 303 observed with the MAGIC telescope
• VLBA images of the precessing jet of LSI+61303
• Long-term OVRO monitoring of LSI+61303: confirmation of the two close periodicities
• Understanding the periodicities in radio and GeV emission from LS I+61303

Cited by in corpus (5)

• Precession-induced Variability in AGN Jets and OJ 287
• 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
• Opacity effect on core-shift and the spectral properties of jets
• Rapid X-ray variability of the gamma-ray binary LS I+61 303