DancingGalaxies · Dancing with giants: dynamics of dwarf satellite galaxies
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2019-05-01 → 2021-04-30
- EU contribution
- €177,599
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Dancing with giants: dynamics of dwarf satellite galaxies
The goal of the project was to determine what the population of satellite galaxies of the Milky Way tells us about the assembly history of our galaxy and also about the nature of dark matter. This was motivated by previous observations that the Milky Way satellites are in tension with the predictions of the standard cosmological model. The Milky Way system is the one we have the largest amount of data for and likely encodes critical information for answering two fundamental problems in physics: what is the nature of dark matter and dark energy?, the two major components of the Universe. The project led to the most up-to-date measurement of the dark matter distribution in our galaxy, from the inner few kiloparsecs up to the edge of the halo, at roughly 220 kiloparsecs. This has been possible by using state-of-the-art hydrodynamical simulations to design models for the distribution of dark matter when accounting for galaxy formation physics. It also showed that the Milky Way dark matter halo is twisted, that is it experiences a sudden 90 degrees reorientation at the edge of the Milky Way stellar disc. Such twists are typically produced due to a reorientation in the past filaments that feed the Milky Way and only a small fraction of haloes in the standard cosmological model experience such a process. It highlights that our galaxy is a special place with its own unique formation history.
Data: CORDIS, © European Union
Project objective
Giant galaxies like our own are surrounded by a large number of dwarf galaxy satellites that perform a complex orbital dance. Theoretical models predict that this dance should be composed of randomly oriented elliptical orbits, but Milky Way (MW) observations reveal the opposite: most satellites orbit in the same plane and have orbits that are more circular than expected. This discrepancy is a major problem that lacks an answer. It could signal a fundamental breakdown of the current cosmological model or, alternatively, that the MW is very atypical, a 1 in 1000 system. Studies of satellite orbits cannot yet be carried out for other galaxies, so the only option is to examine the MW in more detail. My proposed research will deliver ground-breaking new insights into the anomalous dynamics of satellites, and, through this, uncover the formation history of our galaxy. First, I will investigate the phenomena that give rise to the atypical orbits of the MW satellites. Two key drivers are the accretion of satellites along cosmic web filaments and the geometry of the dark matter halo of the central galaxy. Secondly, using state-of-the-art galaxy formation models, I will perform detailed simulations to predict the distribution of faint satellites and the stellar halo of our galaxy. These contain vital clues to the root cause of the anomalous satellite orbits problem. I will compare the model predictions to MW observations to make an unprecedented test of the current cosmological paradigm. The same simulations are essential to understand how representative are the MW satellites and stellar halo, and thus the extent to which they can be used to test the nature of dark matter and galaxy formation models.The proposed research combines my two areas of expertise, large scale structure and satellite galaxies, with the world-leading galaxy formation models and simulations of Prof. Schaye's group, and, together, they provide the ideal setting to make this project a major success.
Original text from CORDIS.
Participants
- UNIVERSITEIT LEIDEN · LeidenCoordinatorNetherlands
Links
Data: CORDIS, © European Union