Infrared and radio study of the W43 cluster

Resolved binaries and non-thermal emission

¹ Dpto. de Ing. Mecánica y Minera, EPSJ, Universidad de Jaén, Campus Las Lagunillas s/n, Edif. A3, 23071 Jaén, Spain
e-mail: peter@ujaen.es
² Departamento de Física, EPSJ, Universidad de Jaén, Campus Las Lagunillas s/n, Edif. A3, 23071 Jaén, Spain
e-mail: ajmunoz@ujaen.es, jmarti@ujaen.es, esayaso@ujaen.es
³ Grupo de Investigación FQM-322, Universidad de Jaén, Campus Las Lagunillas s/n, Edif. A3, 23071 Jaén, Spain
e-mail: jrssutil@ujaen.es
⁴ Instituto Argentino de Radioastronomía (CCT La Plata, CONICET), C.C.5, (1894) Villa Elisa, Buenos Aires, Argentina
e-mail: jcombi@fcaglp.unlp.edu.ar

Received: 20 May 2011
Accepted: 1 July 2011

Abstract

Context. The recent detection of very high-energy (VHE) gamma-ray emission from the direction of the W43 star-forming region prompted us to investigate its stellar population in detail in an attempt to see wether or not it is possible an association.

Aims. We search for the possible counterpart(s) of the gamma-ray source or any hints of them, such as non-thermal synchrotron emission as a tracer of relativistic particles often involved in plausible physical scenarios for VHE emission.

Methods. We data-mined several archival databases with different degrees of success. The most significant results came from radio and near-infrared archival data.

Results. The previously known Wolf-Rayet star in the W43 central cluster and another cluster member appear to be resolved into two components,suggesting a likely binary nature. In addition, extended radio emission with a clearly negative spectral index is detected in coincidence with the W43 cluster. These findings could have important implications for possible gamma-ray emitting scenarios, which we also briefly discuss.