Using numerical simulations, we aim at a deeper theoretical understanding of the origin and evolution of complex
stellar and gaseous structures in galactic nuclei as well as their interaction with central black holes. One of our primary
focus will be the physics of nearby galactic nuclei that show Seyfert activities, together with the currently inactive Milky
Way and Andromeda galaxy as well as the puzzle of the anti-hierarchical black hole growth.
Main topics and goals
Gas and dust structure and nuclear star formation
- origin of the thick turbulent (clumpy) gas tori?
- effects of turbulence in tori: thermal state, geometry,
angular momentum transport, fueling of the SMBH?
- turbulence driver: radiative heating and pressure, jets
and winds, rotation and shear or star formation?
- star formation in tori: nuclear stellar clusters or rings?
- mass accretion and ejection mechanisms in the nucleus?
- evolutionary sequence including inactive states?
- origin of the anti-hierarchical black hole growth?
The quiescent nucleus of the Milky Way
- why currently inactive? How to trigger active phases?
- origin of the hot bubble, the circumnuclear stellar
disks (former torus?) and mini-spiral?
The nucleus of the Andromeda Galaxy
- origin of the outer eccentric old (P1+P2) stellar disks?
- inner young disk (P3) the result of mass loss of stars
of the P1+P2 disk?
Origin of the anti-hierarchical growth of black holes
We calculate black hole growth rates,
based on merger trees from
cosmological dark matter simulations
with the GADGET-2 code. These will
be confronted with the observed
quasar luminosity evolution (quasar
downsizing). Michaela Hirschmann
Star formation in the galactic center
A molecular cloud is put into the potential of a
supermassive black hole. We study
disruption, disk-phase and fragmentation.
Such a scenario might lead to a stellar
disk, as seen in our own galactic center.
The picture shows the capturing of a
cloud of 10^5 solar masses after 0.5
Myrs by a black hole of 10^6 solar masses.
Radiation driven turbulence in molecular tori
Radiation from AGN might drive turbulence within the torus, which
could keep it thick. We aim to perform 3D hydrodynamic
simulations with radiative transfer to address this. The example
gives an impression how a density slice looks like, and an
integration of the total optical depth due to hydrogen and dust
extinction at a wavelength just shortward of the Lyman edge.
Turbulence in AGN tori
We study the characteristics of turbulence
in AGN tori, stirred by discrete energy
input mechanisms like supernova
explosions or stellar winds and determine
the timescales of the decay of the
thickness of the resulting density
distribution. Below, a cut along a
meridional plane is displayed after 10 orbits.
This study will show us, whether long term
stirring processes are needed.
For further information, we refer to the individual pages of the members of
© Physics of galactic nuclei Group at MPE
last update: 25/01/2010