Speaker
Description
The investigation of the large-scale distribution of neutral hydrogen (HI) within the cosmic web is fundamental in comprehending the intricate processes governing galaxy formation and evolution. Evidently, the star formation rate observed throughout cosmic history necessitates galaxies to continually replenish their gas reservoir. Theoretical simulations predict that this replenishment primarily occurs via accretion of pristine gas situated within the Inter Galactic Medium (IGM). Nonetheless, the detection and comprehensive characterization of these HI clouds have proven to be formidable endeavors, due to their faint luminosity, compact nature, and sparse distribution. By applying the spectral stacking technique to data from the MeerKAT Observations of Nearby Galactic Objects: Observing Southern Emitters (MHONGOOSE) survey and to state-of-art cosmological simulations, I found a substantial difference in the amount of neutral gas surrounding the mock galaxies and the observed galaxies. In particular, the gas detected via spectral stacking the cosmological simulations is not found in the MHONGOOSE data, suggesting that simulations overpredict the column density of the neutral medium in the outskirt of galaxies. In the talk I will also focus on the limitation of the stacking technique and the need of deeper observations in order to detect the emission of the pristine gas predicted to fueling the star formation over cosmic time.
