Husemann, B. and Bielby, R. and Jahnke, K. and Arrigoni-Battaia, F. and Worseck, G. and Shanks, T. and Wardlow, J. and Scholtz, J. (2018) Cosmic dance at z ~ 3 : Detecting the host galaxies of the dual AGN system LBQS 0302–0019 and Jil with HAWK-I+GRAAL. Astronomy and Astrophysics, 614: L2. ISSN 1432-0746
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Abstract
We recently discovered that the luminous radio-quiet quasi-stellar objects (QSO) LBQS 0302-0019 at z = 3.286 is likely accompanied by an obscured AGN at 20 kpc projected distance, which we dubbed Jil. It represents the tightest candidate system of an obscured and unobscured dual AGN at z > 3. To verify the dual AGN scenario, we obtained deep Ks band (rest-frame V band) imaging with the VLT/HAWK-I+GRAAL instrument at 0.″4 resolution during science verification in January 2018. We detect the individual host galaxies of the QSO and Jil with estimated stellar masses of log(M⋆/M⊙) = 11.4 ± 0.5 and log(M⋆/M⊙) = 0.9 ± 0.5, respectively. Near-IR spectra obtained with Very Large Telescope-K-band Multi Object Spectrograph (VLT-KMOS) reveal a clear [O III] λ5007 line detection at the location of Jil that does not contribute significantly to the Ks band flux. Both observations therefore corroborate the dual AGN scenario. A comparison to Illustris simulations suggests a parent halo mass of log(Mhalo/M⊙) = 13.2 ± 0.5 for this interacting galaxy system, corresponding to a massive dark matter halo at that epoch. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme(s) 60.A-9471(A) and 100.A-0134(B).