Name: Damian Mast

Institution: Observatorio astronomico de Cordoba

e-mail: damianmast(no-spam)gmail.com

Partner Contry: ARG

Science Meeting: Yes

User Meeting: Yes

NGO Staff Meeting: None Selected

Presentation: Yes

Format: Oral

Title: Unveiling the nature of the nearby starburst nucleus. CIRPASS and NIRI spectroscopy of M83

Co-author: Diaz Rubin Dottori Horacio Rodrigues Irapuan Agaero Maria Paz

Co-authors' Institutions: GEMINI Observatory, La Serena, Chile Dpt. of Astronomy, IF-UFRGS, Porto Alegre, Brazil IP&D-Universidade do Vale do Paraiba, Sao Paulo, Brazil Observatorio Astronomico de Cordoba-UNC, Cordoba, Argentina

Abstract:The huge star formation events that occur at some galactic centers do not provide enough clues as to their origin, since the morphological signatures of the triggering mechanism are smeared out in the timescale of a few orbital revolutions of the galaxy core. We performed a spectroscopy study using 3D J-band and Long Slit K-band observations. These spectra allow us to analyze the kinematical behaviour of the gaseous and stellar components. Our high spatial resolution three-dimensional near-infrared spectroscopy reveals that a hidden mass concentration is located exactly at the youngest end of a giant star-forming arc. This location, the inferred average cluster ages, and the dynamical times clearly indicate that the interloper has left behind a spur of violent star formation in M83, in a transient event lasting less than one orbital revolution. The study of the origin (bar funneling or cannibalized satellite) and fate (black hole merging or giant stellar cluster) of this sys! tem could provide clues to the question of core growing and morphological evolution in grand-design spiral galaxies. In particular, our TreeSPH numerical modeling (see the corresponding contribution in this meeting) suggests that the two nuclei could coalesce, forming a single massive core of 1E7 solar masses in about 60 million years or less. On the other hand, using the several stellar absorption and emission lines present in the Long Slit spectra, we can perform a better characterization of the underlying stellar population, minimizing dust effects. The main result is a pronounced rotational motion of the k-giant population, with an amplitud of 200 km sec-1 in the central 15 arcsec, and a Sigma-drop of the radial velocity dispersion in the central 3 arcsec. These last results indicate that the intermediate age stellar population would be arranged in a thin massive circumnuclear disk.