Speaker
Description
Understanding how galaxies evolve over cosmic time is a central goal of modern astrophysics and requires a detailed understanding of the baryon cycle. More than 80% of the baryons associated with galaxies reside in the circumgalactic medium (CGM), making it a key driver of galaxy evolution. Quasar absorption line surveys of distant galaxies show that approximately 20-25% of galaxy halos exhibit both low and high ionization gas, suggesting the presence of density variations within the CGM. While such systems are commonly modeled using discrete two-phase media, maintaining pressure equilibrium between the phases remains challenging.
In this work, we adopt a globule model with a continuous density profile, consisting of a high density core and a low density surface in equilibrium with the ambient medium. Using Cloudy photoionization calculations, we reproduce absorption in cool gas clouds that also exhibit high-ionization species. For the first time, we show that for density slopes in the range 1.75-2.25, the ambient density is constrained to be between $10^{-6}$ and $10^{-5}\,\mathrm{cm^{-3}}$. In future work, we will quantify the fraction of such systems explained by globule structures, with implications for multiphase gas formation and pressure support in the CGM.
| Participate the oral/poster presentation award competition | Yes |
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