The Origins of the Circumgalactic Medium in the FIRE Simulations

Understand

We use a particle tracking analysis to study the origins of the circumgalactic medium (CGM), separating it into (1) accretion from the intergalactic medium (IGM), (2) wind from the central galaxy, and (3) gas ejected from other galaxies.

• Our sample consists of 21 FIRE-2 simulations, spanning the halo mass range log(Mh/Msun) ~ 10-12 , and we focus on z=0.25 and z=2.
• Owing to strong stellar feedback, only ~L* halos retain a baryon mass >~50% of their cosmic budget.
• Metals are more efficiently retained by halos, with a retention fraction >~50%.