Extraplanar gas and gas accretion in spiral galaxies
Filippo FRATERNALI
Université de Bologne
Résumé :
Over the last years, evidence has been accumulating
that nearby spiral galaxies are surrounded by massive haloes
of cold gas, which rotate more slowly than their discs
and show inflow motions. Such extraplanar (halo) gas is
observed in galaxies with different properties
(such as masses and SFRs) and it is analogous to the
Intermediate and High Velocity Clouds of the Milky Way.
The peculiar kinematics of the extraplanar gas cannot
be explained by supernova outflows (galactic fountains)
alone, instead it appears to be the result of interactions
between fountain gas and accreting material. The amount
of infall needed to reproduce the data is of the
order of the SFR of the host galaxy. This suggests that spiral
galaxies are accreting a significant mass of gas from the
intergalactic medium and are still growing today.
