Is the stellar system WR 11 a gamma-ray source?

Abstract

Many early-type stars are in systems; some of them have been indicated as putative high-energy emitters. The radiation is expected to be produced at the region where two stellar winds collide. Compelling evidence of such emission was found only for the colliding-wind binary (CWB) Eta Car, which was associated to a GeV source. Very recently, the closest CWB, WR 11, was proposed as a counterpart of a 6sigma emission excess, measured with the Fermi LAT satellite. We looked for evidence to support or reject the hypothesis that WR 11 is responsible of the gamma-ray excess. Archive radio interferometric data at 1.4 and 2.5 GHz taken with the Australia Telescope Compact Array along sixteen different dates were reduced. The sizes of the field-of-view at 2.5 GHz and of the central region of the Fermi LAT excess are alike. We analyzed the emission of the field of WR 11, characterized the radio sources detected and derived their spectral indices, to investigate their nature. Eight sources with fluxes above 10 mJy were detected at both frequencies. All but one (WR 11) showed negative spectral indices. Four of them were identified with known objects, including WR 11. A fifth source, labeled here S6, could be a promising candidate to produce gamma-ray emission, besides the CWB WR 11.

The paper has been accepted for publication in PASA; 11 pages

References in corpus (12)

• A Spitzer view of protoplanetary disks in the gamma Velorum cluster
• The Gaia-ESO Survey: Kinematic structure in the Gamma Velorum Cluster
• Detection of Gamma-ray Emission from the Eta-Carinae Region
• γ^2 Velorum: Orbital Solution and Fundamental Parameter Determination with SUSI
• Direct constraint on the distance of y2 Velorum from AMBER/VLTI observations
• Unveiling the nature of the unidentified gamma-ray sources V: analysis of the radio candidates with the kernel density estimation
• The Fermi LAT view of the colliding wind binaries
• Simulating three-dimensional nonthermal high-energy photon emission in colliding-wind binaries
• High-energy particle transport in 3D hydrodynamic models of colliding-wind binaries
• On the origin of γ-ray emission in η Carina
• Very Large Array and Jansky Very Large Array observations of the compact radio sources in M8
• Radio detections towards unidentified variable EGRET sources

Cited by in corpus (6)

• A model for the non-thermal emission of the very massive colliding-wind binary HD 93129A
• Hints of gamma-ray orbital variability from gamma^2 Velorum
• Colliding-wind binary systems: Diffusive shock acceleration and non-thermal emission
• Hints about the multiplicity of WR 133 based on multiepoch radio observations
• Investigation of the WR 11 field at decimeter wavelengths
• On the orbital variability of gamma-ray emission in ${\gamma }^2$ Velorum