Speaker
Description
The diffuse intragroup light (IGL) is a pervasive feature of galaxy groups consisting of an extended low-surface-brightness component that permeates the intergalactic medium of these galaxy associations. It is believed to form from stars removed from the outermost regions of the galaxies, or that have formed in situ due to the numerous close interactions during the initial phases of galaxy group formation. We used controlled numerical simulations to investigate the formation and evolution of IGL in galaxy groups during the pre-virialization phase. Our simulations involved groups of varying total mass and number of members, allowing us to explore how the IGL evolves over cosmic time and its potential in understanding the assembly history of these systems. By employing a surface brightness cutoff to distinguish between galactic and intergalactic light, our study reveals that the emergence of this diffuse faint component typically begins around the turnaround epoch and persists steadily thereafter. We analyzed the correlation between the mass and fraction of IGL and various group properties, finding a sublinear relationship between the mass of IGL and the brightest group galaxy, suggesting intertwined formation histories with potentially differing growth rates and distinct driving mechanisms. Additionally, we observed a negative correlation between the IGL fraction and the group’s velocity dispersion, indicating that IGL formation efficiency is primarily influenced by internal group dynamics. Lower velocity dispersion may enhance IGL formation through increased gravitational interaction effectiveness. Furthermore, our analysis of the 3D density profiles of IGL compared to those of the total system mass revealed significant similarities, suggesting that IGL serves as a reliable tracer of the gravitational potential of host groups, even when these galaxy aggregations are not in dynamic equilibrium.
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