Speaker
Description
Gas deposition processes in the galaxy play a critical role for the promotion of thin discs, e.g. the hot mode accretion allows the mixing of gas in the circum-galactic medium (CGM), leading to a more coherent accretion, and enhancing the disc formation. But there is no consensus on how the gas accretion proceses affect the CGM or how are manifested in models.
In this work we use five models of the VINTERGATAN simulation suite to study the evolution of the CGM in Milky Way-mass halos, focusing on the mechanisms of gas filling and draining over cosmic time. Three of the models are obtained with the novel Genetic Modification Technique (GMT), which allows us to investigate how controlled changes in the assembly history of galaxies, e.g. the timing of merger and masses, influence the development of the CGM.
Three of our models, one is a GMT-model, show short-timescale depletions of the gas fraction in the CGM before and after the virialization of the CGM. These depletions can account for a loss of 10-20% over a few giga-years. The depletions are driven by thermal instabilities, hot and cold accretion and hot-diffuse outflows (exceeding the virial radius). Also, and suggested by the MGT-models, these depletions can be manifested when the mass of last major merger is changed. This finding confronts the idea of a static post-virialization hot CGM. Finally, the virialization epoch occurs at redshift z>2, much earlier than other models such as the FIRE simulations. Hence, we study the features of the baryonic cycle to enable this early virialization.
