{\bf Superwind Outflows in Seyfert Galaxies? : Large-Scale Radio Maps of an Edge-On Sample}

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Session 23 -- Low-Luminosity AGNs
Display presentation, Tuesday, June 13, 1995, 9:20am - 6:30pm

[23.04] {\bf Superwind Outflows in Seyfert Galaxies? : Large-Scale Radio Maps of an Edge-On Sample}

E. Colbert, J. Gallimore (STScI \& UMD), S. Baum, C. O'Dea (STScI)

\catcode`\@=11 \def\gapprox{\mathrel{\mathpalette\@versim>}} \def\lapprox{\mathrel{\mathpalette\@versim<}} \def\@versim#1#2{\lower2.45pt\vbox{\baselineskip0pt\lineskip0.9pt \ialign{$\m@th#1\hfil##\hfil$\crcr#2\crcr\sim\crcr}}} \catcode`\@=12 Large-scale galactic winds (superwinds) are commonly found flowing out of the nuclear region of ultraluminous infrared and powerful starburst galaxies. Stellar winds and supernovae from the nuclear starburst provide the energy to drive these superwinds. The outflowing gas escapes along the rotation axis, sweeping up and shock-heating clouds in the halo, which produces optical line emission, radio synchrotron emission, and X-rays. These features can most easily be studied in edge-on systems, so that the wind emission is not confused by that from the disk.

We have begun a systematic search for superwind outflows in Seyfert galaxies. In an earlier optical emission-line survey, we found extended minor axis emission and/or double-peaked emission line profiles in $\gapprox$30\% of the sample objects. We present here large-scale (6cm VLA C-config) radio maps of 11 edge-on Seyfert galaxies, selected (without bias) from a distance-limited sample of 23 edge-on Seyferts. These data have been used to estimate the frequency of occurrence of superwinds. Preliminary results indicate that four (36\%) of the 11 objects observed and six (26\%) of the 23 objects in the distance-limited sample have extended radio emission oriented perpendicular to the galaxy disk. This emission may be produced by a galactic wind blowing out of the disk. Two (NGC~2992 and NGC~5506) of the nine objects for which we have both radio and optical data show good evidence for a galactic wind in both datasets. We suggest that galactic winds occur in $\gapprox$30\% of all Seyferts. A goal of this work is to find a diagnostic that can be used to distinguish between large-scale outflows that are driven by starbursts and those that are driven by an AGN. The presence of starburst-driven superwinds in Seyferts, if established, would have important implications for the connection between starburst galaxies and AGN.

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