The MAGIC highlights of the gamma ray binary LS I +61 303

TL;DR

This study presents the first detailed analysis of TeV gamma-ray emission from LS I +61 303, revealing its periodic nature, spectral characteristics, and correlated X-ray and gamma-ray outbursts, advancing understanding of particle acceleration in such systems.

Contribution

The paper provides the first comprehensive multiwavelength observational campaign of LS I +61 303, demonstrating its periodic TeV emission and correlation with X-ray activity, offering new insights into emission mechanisms.

Findings

Periodic TeV gamma-ray emission at phase 0.6-0.7

No spectral variation along the orbit

Correlated X-ray and TeV outbursts

Abstract

The discovery of emission of TeV gamma rays from X-ray binaries has triggered an intense effort to better understand the particle acceleration, absorption, and emission mechanisms in compact binary systems. Here we present the pioneering effort of the MAGIC collaboration to understand the very high energy emission of the prototype system LS I +61 303. We report on the variable nature of the emission from LS I +61 303 and show that this emission is indeed periodic. The system shows regular outburst at TeV energies in phase phi=0.6-0.7 and detect no signal at periastron (phi~ 0.275). Furthermore we find no indication of spectral variation along the orbit of the compact object and the spectral energy distribution is compatible with a simple power law with index Gamma=2.6+-0.2_(stat)+-0.2_(sys). To answer some of the open questions concerning the emission process of the TeV radiation we conducted a multiwavelength campaign with the MAGIC telescope, XMM-Newton, and Swift in September 2007. We detect a simultaneous outburst at X-ray and TeV energies, with the peak at phase 0.62 and a similar shape at both wavelengths. A linear fit to the strictly simultaneous X-ray/TeV flux pairs provides r=0.81 -0.21 +0.06. Here we present the observations and discuss the implications of the obtained results to the emission processes in the system.