NOAO >   Observing Info >   Approved Programs >   2003A-0134

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Proposal Information for 2003A-0134


PI: Henrique R. Schmitt, National Radio Astronomy Observatory, hschmitt@aoc.nrao.edu
Address: 1003 Lopezville, Socorro, NM 87801, USA

CoI: Roberto Cid Fernandes, Univ. Fed. de Santa Catarina - Brazil
CoI: Thaisa Storchi-Bergmann, Univ. Fed. do Rio Grande do Sul - Brazil

Title: The circumnuclear stellar population and black hole masses of Seyfert galaxies

Abstract: Recent optical and UV studies have been very succesful in detecting starbursts around the nuclei of Seyfert 2 galaxies (Sy2). While these findings have substantially advanced our understanding of the \it Starburst-AGN connection, there are still several key missing pieces in this puzzle. About 1/3 of nearby Sy2's present an UV-excess whose nature simply cannot be determined based on optical-UV diagnostics of their inner stellar populations. Also, such diagnostics fail miserably for Sy1's due to the blinding glare of the nucleus. We propose to use CaII triplet observation, combined with HST ultraviolet, optical and near-infrared observations to determine the nature of the circumnuclear stellar populations for a sample of Sy galaxies. This will be done using the HST images and by means of the mass-to-light ratio at ~ 8500 Ainferred from medium resolution spectroscopy of the CaII absorption triplet. This provides a powerful discriminant between young and old populations, circumventing the difficulties faced in the optical- UV. The data will also allow us to assess implications for unification theories and to estimate nuclear black-hole masses, thus contributing to build a more complete picture of the Starburst-AGN connection.


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