Investigating Particle Acceleration in the Wolf-Rayet Bubble G2.4+1.4

Abstract

The supersonic winds produced by massive stars carry a large amount of kinetic power. In numerous scenarios such winds have been proven to produce shocks in which relativistic particles are accelerated emitting non-thermal radiation. Here, we report the first detection of non-thermal emission from a single stellar bubble, G2.4+1.4, associated with a WO star. We observed this source with the uGMRT in Band 4 ($550-850$ MHz) and Band 5 ($1050-1450$ MHz). We present intensity and spectral index maps for this source that are consistent with synchrotron emission (average spectral index, $\alpha =-0.83\pm 0.10$). The fraction of the available kinetic wind power that is converted into cosmic ray acceleration is estimated to be of the order of a few per cent. This finding constitutes an observational breakthrough and gives new insight on the non-thermal physical processes taking place in the environments of isolated massive stars. In particular, our results show that non-runaway isolated massive stars are capable of accelerating relativistic particles and are therefore confirmed as sources of Galactic cosmic rays.

arXiv comment9 pages, 3 figures, accepted for publication in ApJL

References in corpus (17)

• Radio emission from Supernova Remnants
• The radio emission from the Galaxy at 22 MHz
• Catalogue of particle-accelerating colliding-wind binaries
• The Galactic WC and WO stars: The impact of revised distances from Gaia DR2 and their role as massive black hole progenitors
• Non-thermal emission processes in massive binaries
• GMRT observations of X-shaped radio sources
• Detection of nonthermal emission from the bow shock of a massive runaway star
• Diffuse gamma-ray emission in the vicinity of young star cluster Westerlund 2
• Non-thermal processes in bowshocks of runaway stars. Application to Zeta Oph
• Deciphering the ionized gas content in the massive star forming complex G75.78+0.34
• On the X-ray temperature of hot gas in diffuse nebulae
• WISE morphological study of Wolf-Rayet nebulae
• Particle acceleration in supernova-remnant shocks
• Detection of non-thermal emission from the massive protostellar jet HH80-81 at low radio frequencies using GMRT
• Particle acceleration in the Herbig-Haro objects HH 80 and HH 81
• Runaway massive stars as variable gamma-ray sources
• Multi-zone non-thermal radiative model for stellar bowshocks

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• On the ring nebulae around runaway Wolf-Rayet stars
• On the bipolarity of Wolf-Rayet nebulae
• And then they were two: detection of non-thermal radio emission from the bow shocks of two runaway stars
• Probing the physical conditions and star formation processes in the Galactic HII region S305
• The high-energy emission from HD~93129A near periastron
• Non-thermal emission in hyper-velocity and semi-relativistic stars
• The integrated radio spectrum of G2.4$+$1.4
• Low-frequency spectra of neutron star + OB supergiant binaries: Does wind density drive persistent and flaring modes of accretion?
• Diffuse Hot Plasma in the Interstellar Medium and Galactic Outflows