MHD simulations of the ISM: The importance of the galactic magnetic field on the ISM "phases"

Autor(en)

Miguel A. de Avillez, Dieter Breitschwerdt

Abstrakt

We have carried out 1.25 pc resolution MHD simulations of the ISM, on a Cartesian grid of 0 = (x, y) = 1 kpc size in the galactic plane and -10 = z = 10 kpc into the halo, thus being able to fully trace the time-dependent evolution of the galactic fountain. The simulations show that large scale gas streams emerge, driven by SN explosions, which are responsible for the formation and destruction of shocked compressed layers. The shocked gas can have densities as high as 800 cm-3 and lifetimes up to 15 Myr. The cold gas is distributed into filaments which tend to show a preferred orientation due to the anisotropy of the flow induced by the galactic magnetic field. Ram pressure dominates the flow in the unstable branch 102 <T = 103.9 K, whereas for T = 100 K (stable branch) magnetic pressure takes over. Near supernovae thermal and ram pressures determine the dynamics of the flow. Up to 80% of the mass in the disk is concentrated in the thermally unstable regime 102 <T = 10 3.9 K with ~30% of the disk mass enclosed in the T = 10 3 K gas. The hot gas in contrast is controlled by the thermal pressure, since magnetic field lines are swept towards the dense compressed walls.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Universidade de Évora

Journal

Astrophysics and Space Science

Band

292

Seiten

207-214

Anzahl der Seiten

8

ISSN

0004-640X

DOI

https://doi.org/10.1023/B:ASTR.0000045019.24124.91

Publikationsdatum

2004

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/a4b6e42a-6330-46f2-a6a7-1c48e9800db6