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Date and Time of the Query: 2019-06-26 T17:30:11 PDT
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For refcode 1993ApJ...419..553B:
Retrieve 13 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
1993ApJ...419..553B KILOPARSEC-SCALE RADIO EMISSION IN SEYFERT GALAXIES: EVIDENCE FOR STARBURST-DRIVEN SUPERWINDS? S. A. BAUM, C. P. O'DEA, D. DALLACASSA, A. G. DE BRUYN, AND A. PEDLAR Received 1993 March 31; accepted 1993 July 2 ABSTRACT We report the results of a pilot program to search for kiloparsec- scale radio emission in 13 Seyfert galaxies, using the Westerbork Synthesis Radio Telescope. While it has been known for some time now that Seyfert galaxies generally contain nuclear, subkiloparsec-scale radio sources, this is the first systematic attempt to image larger scale radio emission in Seyfert galaxies. These observations reveal the presence of kiloparsec-scale, diffuse, sometimes bubble-like radio emission in 12 of these sources. This large-scale, "extra-nuclear" radio emission is randomly oriented with respect to the small-scale nuclear radio source axis but tends to align with the minor axis of the host galaxy disk. We find that the ratio of nuclear to extra-nuclear radio flux density varies greatly-in some sources the nuclear emission dominates and in others the extra-nuclear component contributes the majority of the source's radio flux density. The radio flux density of the extra-nuclear radio emission agrees roughly with the flux density predicted from the 60 micron flux density, using the empirical relationship between radio and far-IR flux densities found for star-forming regions. The radio morphology and orientation of the extra-nuclear radio emission we have detected in these Seyfert galaxies, its radio luminosity, and the correlation of that luminosity with the far-IR luminosity of the galaxy all suggest that this radio emission may be the manifestation of a circumnuclear starburst. In this model, the starburst generates the cosmic-ray electrons responsible for the extra-nuclear radio emission and then sweeps the radio-emitting plasma out along the minor axis of the galaxy disk in a starburst-driven superwind. We have found extra-nuclear, minor axis radio emission both in Seyfert galaxies whose radio and far-IR properties appear to be dominated by a starburst and Seyfert galaxies in which an AGN dominates the radio and far-IR emission. We present independent evidence taken from the literature that minor axis radio emission and starbursts are not uncommon in Seyfert galaxies. Thus, while the relative importance of the AGN and starburst components seems to vary greatly from Seyfert to Seyfert, circumnuclear starbursts and starburst-driven winds may be a common feature of Seyfert galaxies. Subject headings: galaxies: Seyfert - galaxies: stellar content - radio continuum: galaxies - stars: formation
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