Abstract
Feedback from active galactic nuclei (AGN) has become a major component in simulations of
galaxy evolution, in particular for massive galaxies. AGN jets have been shown to provide a
large amount of energy and are capable of quenching cooling flows. Their impact on the host
galaxy, however, is still not understood. Subgrid models of AGN activity in a galaxy evolution
context so far have been mostly focused on the quenching of star formation. To shed more light
on the actual physics of the ‘radio mode’ part of AGN activity, we have performed simulations
of the interaction of a powerful AGN jet with the massive gaseous disc (1011 M) of a
high-redshift galaxy. We spatially resolve both the jet and the clumpy, multi-phase interstellar
medium (ISM) and include an explicit star formation model in the simulation. Following the
system over more than 107 yr, we find that the jet activity excavates the central region, but
overall causes a significant change to the shape of the density probability distribution function
and hence the star formation rate due to the formation of a blast wave with strong compression
and cooling in the ISM. This results in a ring- or disc-shaped population of young stars. At later
times, the increase in star formation rate also occurs in the disc regions further out since the
jet cocoon pressurizes the ISM. The total mass of the additionally formed stars may be up to
1010 M for one duty cycle. We discuss the details of this jet-induced star formation (positive
feedback) and its potential consequences for galaxy evolution and observable signatures.
galaxy evolution, in particular for massive galaxies. AGN jets have been shown to provide a
large amount of energy and are capable of quenching cooling flows. Their impact on the host
galaxy, however, is still not understood. Subgrid models of AGN activity in a galaxy evolution
context so far have been mostly focused on the quenching of star formation. To shed more light
on the actual physics of the ‘radio mode’ part of AGN activity, we have performed simulations
of the interaction of a powerful AGN jet with the massive gaseous disc (1011 M) of a
high-redshift galaxy. We spatially resolve both the jet and the clumpy, multi-phase interstellar
medium (ISM) and include an explicit star formation model in the simulation. Following the
system over more than 107 yr, we find that the jet activity excavates the central region, but
overall causes a significant change to the shape of the density probability distribution function
and hence the star formation rate due to the formation of a blast wave with strong compression
and cooling in the ISM. This results in a ring- or disc-shaped population of young stars. At later
times, the increase in star formation rate also occurs in the disc regions further out since the
jet cocoon pressurizes the ISM. The total mass of the additionally formed stars may be up to
1010 M for one duty cycle. We discuss the details of this jet-induced star formation (positive
feedback) and its potential consequences for galaxy evolution and observable signatures.
| Original language | English |
|---|---|
| Pages (from-to) | 438-449 |
| Number of pages | 12 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 425 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Sept 2012 |
Keywords
- hydrodynamics, methods: numerical, ISM: clouds, galaxies: jets, galaxies: ISM, galaxies: star formation