Near Infrared Continuum and 3.3microns Polycyclic Aromatic Hydrocarbon Imaging of The Starburst Ring in The Type 1 Seyfert Galaxy NGC 7469

April 1994 • 1994AJ....107.1274M

Authors • Mazzarella, J. M. • Voit, G. M. • Soifer, B. T. • Matthews, K. • Graham, J. R. • Armus, L. • Shupe, D.

Abstract • High resolution near-infrared images of the type 1 Seyfert galaxy NGC 7469 have been obtained to probe its dusty nuclear environment. Direct J, H, and K images are relatively featureless, but residual images created by subtracting a smooth model based on best-fitting elliptical isophotes reveal a tight inner spiral whose high surface-brightness portions correspond to a previously detected 3"(1 kpc) diameter ring of radio continuum emission. The inner infrared spiral arms extended ~14" NW and SE from the nucleus, and the NW arm joins up with large-scale spiral structure visible in the R band. The residual images also show a bar-like structure aligned with the brightest infrared/radio hotspots at PA~50^deg^. Three infrared hotspots are detected which align remarkably well with 6 cm radio continuum sources. The near-infrared ring and the hotspots are visible in the residual images, and in a high-resolution direct K-band image restored to an effective resolution of 0.65" FWHM using the Richardson-Lucy algorithm. The infrared hotspots have luminosities of νL_nu_ (2.2 microns)~10^8^L_sun_(M_K_~ -16 mag), suggesting they are either giant H II regions or individual supernovae. The two brightest regions may be associated with enhanced star formation triggered by orbit crowding of gas where spiral arms emerge from an inner bar. Narrowband ({DELTA}λ/λ~1.5%) imaging in the 3.28 micron dust emission feature and surrounding continuum confirms the 3" diameter 3.28 micron emission region detected previously using multiaperture photometry. The extended polycyclic aromatic hydrocarbon (PAH) emission is slightly elongated and aligned with published [O III] line emission and 12.5 micron continuum emission, apparently tracing the starburst. The presence of ~25% of the total 3.28 micron PAH emission within R < 1" demonstrates that a starburst within the central few hundred parsecs must supply a significant fraction of the infrared continuum from the nucleus, and there is apparently sufficient shielding material between the starburst and the AGN to preserve the PAHs along our line of sight to the nucleus.

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• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=1994AJ....107.1274M
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