Discovery of diffuse radio emission in the galaxy cluster A1689

Aims. The aim of this work is to investigate the possible presence of extended diffuse synchrotron radio emission associated with the intracluster medium of the complex galaxy cluster A1689. Methods. The radio continuum emission of A1689 has been investigated by analyzing archival observations at 1.2 and 1.4GHz obtained with the Very Large Array in different configurations. Results. We report the detection of an extended, diffuse, low-surface brightness radio emission located in the central region of A1689. The surface brightness profile of the diffuse emission at 1.2GHz indicates a central radio brightness of similar or equal to 1.7 mu Jy/arcsec(2) and the 3 sigma radio isophothes reveal the largest linear size to be 730 kpc. Given its central location, the low-level surface brightness, and the comparatively large extension, we classify the diffuse cluster-wide emission in A1689 as a small radio halo.