Speaker
Description
Metal absorption lines are powerful tools for probing the gas content in the universe and illuminating the gas flows around galaxies. Absorption that arises from different ionization states of chemical elements provides insight into various gaseous structures and environments – low-ionization lines trace the cooler, denser regions near galaxies, while high-ionization lines illuminate the hotter, more diffuse regions of the universe. I generate a suite of synthetic quasar absorption-line observations from the TNG100 cosmological simulation at various redshifts to examine the cosmic evolution of gas and metal absorption lines. Using these, I compute the absorber path densities for low- (e.g., MgII), intermediate- (e.g., SiIII), and high-ionization species (e.g., CIV, OVI) and find that TNG100 qualitatively reproduces observed trends – the path densities of different ions evolve with redshift at different rates. Path densities of high-ionization species also peak at lower redshifts compared to their low-ionization counterparts. Quantitatively, TNG100 slightly overpredicts the path densities of various absorbers, suggesting an excess of metal-enriched gas. I further explore this discrepancy using mock absorption-line observations of the CGM of selected galaxies. They support the notion that TNG100 may be overproducing absorbers, potentially due to an overly efficient circulation and redistribution of metals via galactic outflows. I show that these results potentially reflect the implementation of feedback mechanisms—such as AGN-driven winds or supernova feedback—in TNG100 and their implications for modeling gas flows in galaxy evolution.
