Galactic Wind Signatures around High‐Redshift Galaxies

Abstract

We carry out cosmological chemodynamical simulations with different strengths of supernova (SN) feedback and study how galactic winds from star-forming galaxies affect the features of hydrogen (H I) and metal (C IV and O VI) absorption systems in the intergalactic medium at high redshift. We find that the outflows tend to escape to low-density regions, and hardly affect the dense filaments visible in H I absorption. As a result, the strength of H I absorption near galaxies is not reduced by galactic winds, but even slightly increases. We also find that a lack of H I absorption for lines of sight (LOSs) close to galaxies, as found by Adelberger et al., can be created by hot gas around the galaxies induced by accretion shock heating. In contrast to H I, metal absorption systems are sensitive to the presence of winds. The models without feedback can produce the strong C IV and O VI absorption lines in LOSs within 50 kpc from galaxies, while strong SN feedback is capable of creating strong C IV and O VI lines out to about twice that distance. We also analyze the mean transmissivity of H I, C IV, and O VI within 1 h-1 Mpc from star-forming galaxies. The probability distribution of the transmissivity of H I is independent of the strength of SN feedback, but strong feedback produces LOSs with lower transmissivity of metal lines. In addition, strong feedback can produce strong O VI lines even in cases where H I absorption is weak. We conclude that O VI is probably the best tracer for galactic winds at high redshift.