PICS: Deciphering galaxy formation with planetary nebulae - Insights from models and simulations

Planetary nebulae (PNe) have been used for decades as easily detectable tracers in the outskirts of galaxies under the assumption that they directly follow the underlying stellar light. However, the planetary nebula luminosity function (PNLF) still lacks a solid theoretical explanation for its properties, in particular for the brightest PNe that are visible. I will present the first model for PNe in hydrodynamical cosmological simulations (PICS), where PN populations are modeled through small-scale physics within simulated galaxies of diverse evolutionary pathways, resolving much of the tension between theory and observations. By applying PICS to simulated galaxies from the Magneticum Pathfinder cosmological simulation suite, I will show how the resulting PNe can be used to decipher the assembly history of a galaxy by combining the PNLF with their spatial and kinematic properties. A key finding for this is that both the brightest PNe and the shape of the dim PNLF are directly connected to the underlying star formation history and metallicity as the PNe trace different stellar populations. In particular, I will discuss how the dimmer PNe can be used to extract details of the mass accretion history, for which deep and high-resolution observations are necessary. To this end, I will finally show how deep MUSE surveys targeting local galaxies such as GECKOS are capable of detecting these PNe and can benefit from the information gained from them.