First results from 3D-arcsec resolution cm-images of RCW 49/Westerlund 2

BENAGLIA, P.; B. S. KORIBLASKI; C. S. PERI; J. MARTÍ; J. R. SANCHEZ-SUTIL; S. M. DOUGHERTY

Rodas

Workshop; Massive Stars: From α to Ω; 2013

Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing

The HII region RCW 49 and its ionizing cluster conform a large and complex system, widely studied at infrared and optical wavelengths. Very recently, the system was proposed as the counterpart of an unidentified gamma-ray source; two Fermi (GeV-energies) sources were detected in spatial superposition. Available 843 MHz and interferometric data at 1.4 and 2.4 GHz showed two shells. Yet the relation of the radio source with the high energy sources has not been firmly established. We search for evidence of non-thermal radio emission to shed light on the nature of the high energy sources. We implemented cm-observations using the new receivers of the Australia Telescope Compact Array, at 5.5 and 9.0 GHz, with extensive uv-coverage. Archival lower frequency radio data have been re-reduced, and analysed together with data at other energy ranges (optical, infrared, X-rays, gamma-rays). We present here the deepest radio continuum images of RCW 49 ever obtained. They show star forming pillars and filaments. The radio emission mimics the NIR emission. Analysis of spectral index maps indicates the presence of non-thermal emission. The radio results favor distance of ~6 kpc for the complex, and make likely the association with the gamma-ray emission.