Simultaneous long-term monitoring of LS I +61{\deg}303 by OVRO and Fermi-LAT

TL;DR

This study presents nine years of simultaneous radio and gamma-ray observations of LS I +61°303, confirming known periodicities and revealing an offset in long-term modulation between the two wavelengths, suggesting different emission regions.

Contribution

It provides the first long-term simultaneous radio and gamma-ray monitoring of LS I +61°303, revealing an offset in long-term modulation between the two wavelengths.

Findings

Confirmed periodicities at radio and gamma-ray wavelengths.

Discovered an offset in long-term modulation between radio and gamma-ray data.

Suggested different emission locations along the jet.

Abstract

Previous long-term monitorings of the gamma-ray-loud X-ray binary LS I +61{\deg}303 have revealed the presence of a long-term modulation of ~4.5 years. After nine years of simultaneous monitoring of LS I +61{\deg}303 by the Owens Valley Radio Observatory and the Fermi-LAT, two cycles of the long-term period are now available. Here we perform timing-analysis on the radio and the gamma-ray light curves. We confirm the presence of previously detected periodicities at both radio and GeV gamma-ray wavelengths. Moreover, we discover an offset of the long-term modulation between radio and gamma-ray data which could imply different locations of the radio (15 GHz) and GeV emission along the precessing jet.