11 research outputs found

    High-resolution radio observations of Seyfert galaxies in the extended 12-micron sample - II. The properties of compact radio components

    Full text link
    We discuss the properties of compact nuclear radio components in Seyfert galaxies from the extended 12-micron AGN sample of Rush et al.(1993). Our main results can be summarised as follows. Type 1 and type 2 Seyferts produce compact radio components which are indistinguishable in strength and aspect, indicating that their central engines are alike as proposed by the unification model. Infrared IRAS fluxes are more closely correlated with low-resolution radio fluxes than high-resolution radio fluxes, suggesting that they are dominated by kiloparsec-scale, extra-nuclear emission regions; extra-nuclear emission may be stronger in type 2 Seyferts. Early-type Seyfert galaxies tend to have stronger nuclear radio emission than late-type Seyfert galaxies. V-shaped extended emission-line regions, indicative of `ionisation cones', are usually found in sources with large, collimated radio outflows. Hidden broad lines are most likely to be found in sources with powerful nuclear radio sources. Type 1 and type 2 Seyferts selected by their IRAS 12-micron flux densities have well matched properties

    Parsec-scale radio structures in the nuclei of four Seyfert galaxies

    Full text link
    We present 18-cm radio maps of four Seyfert nuclei, Mrk 1, Mrk 3, Mrk 231 and Mrk 463E, made with the European VLBI Network (EVN). Linear radio structures are present in three out of four sources on scales of ~100 pc to ~1 kpc, and the 20-mas beam of the EVN enables us to resolve details within the radio structures on scales of <10 pc. Mrk 3 was also imaged using MERLIN and the data combined with the EVN data to improve the sensitivity to extended emission. We find an unresolved flat-spectrum core in Mrk 3, which we identify with the hidden Seyfert 1 nucleus in this object, and we also see marked differences between the two highly-collimated radio jets emanating from the core. The western jet terminates in a bright hotspot and resembles an FRII radio structure, whilst the eastern jet has more in common with an FRI source. In Mrk 463E, we use the radio and optical structure of the source to argue that the true nucleus lies approximately 1 arcsec south of the position of the radio and optical brightness peaks, which probably represent a hotspot at the working surface of a radio jet. The EVN data also provide new evidence for a 100-pc radio jet powering the radio source in the Type 1 nucleus of Mrk 231. However, the Seyfert 2 galaxy Mrk 1 shows no evidence for radio jets down to the limits of resolution (~10 pc). We discuss the range of radio source size and morphology which can occur in the nuclei of Seyfert galaxies and the implications for Seyfert unification schemes and for radio surveys of large samples of objects.Comment: 23 pages, 7 postscript figures (supplied as separate files), uses AAS aaspp4 LaTeX style file, to appear in the 10 June 1999 issue of The Astrophysical Journa

    A Survey of Kiloparsec-Scale Radio Outflows in Radio-Quiet Active Galactic Nuclei

    Get PDF
    Seyfert galaxies commonly host compact jets spanning 10-100 pc scales, but larger structures (KSRs) are resolved out in long baseline, aperture synthesis surveys. We report a new, short baseline Very Large Array (VLA) survey of a complete sample of Seyfert and LINER galaxies. Out of all of the surveyed radio-quiet sources, we find that 44% (19 / 43) show extended radio structures at least 1 kpc in total extent that do not match the morphology of the disk or its associated star-forming regions. The KSR Seyferts stand out by deviating significantly from the far-infrared - radio correlation for star-forming galaxies, and they are more likely to have a relatively luminous, compact radio source in the nucleus; these results argue that KSRs are powered by the AGN rather than starburst. KSRs probably originate from jet plasma that has been decelerated by interaction with the nuclear ISM. We demonstrate the jet loses virtually all of its power to the ISM within the inner kiloparsec to form the slow KSRs.Comment: to appear in the Astronomical Journal, Vol 132 (projected

    Measurement of the Ωc0\Omega_c^0 lifetime at Belle II

    No full text
    We report on a measurement of the Ωc0\Omega_c^0 lifetime using Ωc0→Ω−π+\Omega_c^0 \to \Omega^-\pi^+ decays reconstructed in e+e−→ccˉe^+e^-\to c\bar{c} data collected by the Belle II experiment and corresponding to 207 fb−1207~{\rm fb^{-1}} of integrated luminosity. The result, τ(Ωc0)=243±48(stat)±11(syst) fs\rm\tau(\Omega_c^0)=243\pm48( stat)\pm11(syst)~fs, agrees with recent measurements indicating that the Ωc0\Omega_c^0 is not the shortest-lived weakly decaying charmed baryon

    Measurement of the Ωc0\Omega_c^0 lifetime at Belle II

    No full text
    We report on a measurement of the Ωc0\Omega_c^0 lifetime using Ωc0→Ω−π+\Omega_c^0 \to \Omega^-\pi^+ decays reconstructed in e+e−→ccˉe^+e^-\to c\bar{c} data collected by the Belle II experiment and corresponding to 207 fb−1207~{\rm fb^{-1}} of integrated luminosity. The result, τ(Ωc0)=243±48(stat)±11(syst) fs\rm\tau(\Omega_c^0)=243\pm48( stat)\pm11(syst)~fs, agrees with recent measurements indicating that the Ωc0\Omega_c^0 is not the shortest-lived weakly decaying charmed baryon
    corecore