Seminar: Modes of star formation in cosmological simulations of Milky Way-like galaxies
- Date: 23 March 2023, 14:00–15:00
- Location: Ångström Laboratory, 80101Å
- Type: Seminar
- Lecturer: Álvaro Segovia Otero, Lund University
- Contact person: Anish Amarsi
The current theory describing the process of star formation is still incomplete. It strives to connect, and trace as a function of redshift, the local properties of star forming regions and the global parameters characterising a galaxy and its surroundings: from giant molecular clouds in isolated nearby discs to gas clumps in interacting galaxies at high redshift. JWST and ALMA are currently providing us with unprecedented data of this process, however, both observations and theory must go hand in hand. In my talk I will use VINTERGATAN, a high resolution cosmological zoom-in simulation of a Milky Way-like galaxy, to pinpoint the physics that determine galactic scale star formation over cosmic time. I will demonstrate the crucial role played by mergers and galaxy interactions in shaping properties of the interstellar medium (ISM), including gas kinematics, and density distribution. The key role played by tidal compression will be highlighted. A picture emerges at high redshift where the galaxy shifts between quiescent periods and starbursts, enabled by the presence of an assembled galactic disc, and seen as drastic changes in the gas depletion times. We find that on scales of individual clouds, the turbulent state and density distribution of the gas results in a constant average star formation efficiency (per free-fall time) of a few percent, with a spread of many orders of magnitude across the galaxy at any given time. This indicates that the most relevant drivers of variations in a galaxy's global depletion time are changes to the gas density distributions, and not the levels of turbulence.
---
We shall leave for lunch at around 12:15. There will be fika after the seminar.