SEMINAR Antonino Marasco: ‘Positive‘ stellar feedback in nearby disc galaxies: gas accretion triggered by the galactic fountain

by Dr Antonino Marasco (INAF/OAPD)

Thursday 23 Feb 2023, 11:30 → 12:30 Europe/Rome

Sala Jappelli (Osservatorio Astronomico di Padova)

Disc galaxies like the Milky Way require a continuous supply of low-metallicity gas to replenish the material used to form stars. While the exact nature of this supply remain elusive, insights can be obtained by studying the interface region between the disc and the halo, where a combination of inflow and outflow features are expected to occur.

In this first part of the talk I will use deep HI observations from the HALOGAS survey to show that virtually all nearby disc galaxies are surrounded by thick HI envelopes, known as extra-planar gas (EPG), with properties (distribution and kinematics) consistent with an origin from stellar feedback triggering a large-scale gas circulation: that is, a galactic fountain.

In the second part, I show that a dynamical model of a galactic fountain can reproduce remarkably well the distribution and kinematics of the EPG in the Milky Way and in the nearby galaxy NGC 2403. The data are consistent with a scenario where the fountain clouds, ejected from the disc by stellar feedback, interact with the pre-existing hot (T~106 K) and metal-poor (Z~0.1 Z⦿) circum-galactic medium, triggering the condensation and subsequent accretion of the latter onto the disc. This ‘fountain-driven’ accretion mechanism may be the main mode by which disc galaxies at low redshift accrete fresh gas to sustain their star formation.

 

 

The seminar will be held on google.meet link:

ID riunione

meet.google.com/bpv-uzpq-wpr

 

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