Analysis of synthetic oviabsorption associated with galaxy groups in simba and tng50 simulations

Abstract

We compare O vi absorption in synthetic spectra from galaxy groups in the SIMBA and TNG50 cosmological hydrodynamic simulations against those observed from the Cosmic Origins Spectrograph (COS)-IGrM survey. We select 14 galaxy groups from each simulation with (Formula presented) 12.89≤log(Mhalo/M⊙)≤13.61, closely matching COS-IGrM, and create 90,000 synthetic spectra per group. We demonstrate the utility of synthetic absorption spectroscopy when comparing simulations with QSO absorption-based observations. We investigate absorber properties such as radial distributions and kinematics with respect to the group and nearest galaxy. The O vi covering fractions (fOVI) in TNG50 (20.62% ± 2.56%) and SIMBA (5.98% ± 0.82%) are both systematically lower than COS-IGrM (44% ± 5%). A kinematic analysis reveals that the vast majority (∼95%) of absorbers in both of the simulations are gravitationally bound. In TNG50, strong absorbers ( (Formula presented) logNOV I>15 ) are located near star-forming galaxies ( (Formula presented) logsSFR>−11 ) within ∼200 kpc, suggesting a physical connection to stellar feedback, whereas SIMBA shows no comparable trend. Furthermore, in TNG50, the occurrence of O vi absorbers at small impact parameters increases with the stellar mass of the nearest galaxy, but shows no dependence on the total stellar mass of the group. In contrast, SIMBA shows no clear correlation with the nearest galaxy’s stellar mass, although groups with higher total stellar mass exhibit a higher detection rate at larger impact parameters. Differences observed in simulations may arise from feedback models and resolution effects. Finally, we show absorber analysis methodology is an important factor when comparing simulations with absorption spectroscopy observations.