Vol. 610
In section 1. Letters to the Editor

Discovery of a dual AGN at z~3.3 with 20 kpc separation

by B. Husemann, G. Worseck, F. Arrigoni Battaia, and T. Shanks A&A 610, L7


In the standard CDM cosmological model, galaxies form through mergers in a hierarchical scenario. Since each galaxy nucleus hosts a super massive black hole, a large number of dual AGN, with separations of a few kpc, is expected. However they have been elusive up to now. Thanks to MUSE on the VLT, the authors report the detection of one of the closest pairs of AGN known at z > 3. The object, dubbed Jil, meaning “neighbor” in the Klingon language (Star Trek universe) is a narrow-line emitter within the 120kpc-wide Ly-alpha nebula of the luminous radio-quiet QSO LBQS 0302-0019 at z = 3.3. Jill emits several high ionization narrow emission lines (HeII, CIV, CIII) and is only 20 kpc away from the QSO in projection. Emission-line diagnostics confirm that the source is likely powered by photoionization of an obscured AGN three orders of magnitude fainter than the QSO.