Very Large Baseline Array observations of Mrk 6: probing the jet-lobe connection

P. Kharb, C.P. O'Dea, S.A. Baum, M.J. Hardcastle, D. Dicken, J. H. Croston, B. Mingo, J. Noel-Storr

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We present the results of high-resolution VLBI (very long baseline interferometry) observations at 1.6 and 4.9 GHz of the radio-loud Seyfert galaxy, Mrk 6. These observations are able to detect a compact radio core in this galaxy for the first time. The core has an inverted spectral index (α1.6 4.9 = +1.0 ± 0.2) and a brightness temperature of 1 × 108 K. Three distinct radio components, which resemble jet elements and/or hotspots, are also detected. The position angles of these elongated jet elements point not only to a curved jet in Mrk 6, but also towards a connection between the AGN and the kpc-scale radio lobes/bubbles in this galaxy. Firmer constraints on the star formation rate provided by new Herschel observations (SFR <0.8 M⊙ yr-1) make the starburst-wind-powered bubble scenario implausible. From plasma speeds, obtained via prior Chandra X-ray observations, and ram pressure balance arguments for the interstellar medium and radio bubbles, the north-south bubbles are expected to take 7.5 × 106 yr to form, and the east-west bubbles 1.4 × 106 yr. We suggest that the jet axis has changed at least once in Mrk 6 within the last ≈107 yr. A comparison of the nuclear radio-loudness of Mrk 6 and a small sample of Seyfert galaxies with a subset of low-luminosity FR I radio galaxies reveals a continuum in radio properties.
Original languageEnglish
Pages (from-to)2976-2987
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date17 Apr 2014
Publication statusPublished - 1 Jun 2014


  • Galaxies: active
  • Galaxies: individual: mrk 6
  • Galaxies: jets
  • Galaxies: seyfert
  • Techniques: high angular resolution
  • Techniques: interferometric


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