Bibcode
Monreal-Ibero, A.; Colina, L.; Arribas, S.
Bibliographical reference
Science Perspectives for 3D Spectroscopy, Eso Astrophysics Symposia European Southern Observatory, Volume . ISBN 978-3-540-73490-1. Springer-Verlag Berlin Heidelberg, 2007, p. 221
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2007
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Description
In this contribution we present the analysis of the ionization structure
of a sample of six low-z Ultraluminous Infrared Galaxies using Integral
Field Spectroscopy. We discuss the possible ionizing mechanisms
responsible, focussing especially on the external regions (d ˜ 2 -
10 kpc). The observed line ratios are better explained by the presence
of shocks with velocities of 150 to 500 km s-1. This is
supported by the existence of a positive correlation between the
ionization state and the velocity dispersion, especially when using the
[O i]λ6300/Ha ratio. We discuss the origin of these shocks. We
find no evidence for signatures of superwinds in the extranuclear
regions. We propose as an alternative explanation the existence of
tidally induced large-scale gas flows caused by the merging process
itself as the mechanism causing these shocks. Finally, there is one
galaxy where the line ratios in the external regions cannot be explained
by shocks.