Low Intensity AGN Activity in Giant LSB Galaxies

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Session 46 -- Seyfert Galaxies and LINERS
Display presentation, Thursday, January 13, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[46.12] Low Intensity AGN Activity in Giant LSB Galaxies

P.Knezek (UMich), J.Schombert (IPAC/Caltech)

We have completed a spectroscopic survey of the nuclei of 50 giant LSB galaxies selected to be massive in HI gas (M$_{HI} >$ 10$^{10}$ M$_{\odot}$). We find that 65\% of the sample have low intensity nuclear emission that is unrelated to star formation, but is strongly correlated with the presence of a stellar bulge. For objects with high S/N, we obtain ratios of H$\alpha$/N[II] which indicate that a majority of the nuclear activity more closely resembles that observed in LINER systems, rather than Seyfert phenomenon. Furthermore, we measure a mean FWHI for the sample of 1000 km/s, which is slightly narrower than that found for a standard BLR Seyfert. Since these systems were selected to have a high total gas mass, the low intensity of the activity may indicate that the low surface density of the disk material results in a low fueling rate for the central engine. LSB galaxies preferentially inhabit low density galaxy environments. Thus, perhaps the correlation of the bulge with low-level AGN activity indicates that an initial perturbation which causes the formation of a bulge also provides a means of fueling an AGN at a low rate. In order to have strong AGN activity, and a high stellar density, however, a trigger from galaxy interactions is necessary.

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