Cosmological Feedback from High‐Redshift Dwarf Galaxies

We model how repeated supernova explosions in high-redshift dwarf starburstgalaxies drive superbubbles and winds out of the galaxies. We compute theefficiencies of metal and mass ejection and energy transport from the galacticpotentials, including the effect of cosmological infall of external gas. Thestarburst bubbles quickly blow out of small, high-redshift, galactic disks, butmust compete with the ram pressure of the infalling gas to escape intointergalactic space. We show that the assumed efficiency of the star formationrate dominates the bubble evolution and the metal, mass, and energy feedbackefficiencies. With star formation efficiency f*=0.01, the ram pressure ofinfall can confine the bubbles around high-redshift dwarf galaxies withcircular velocities v_c>52 km/s. We can expect high metal and mass ejectionefficiencies, and moderate energy transport efficiencies in halos withv_c~30-50 km/s and f*~0.01 as well as in halos with v_c~100 km/s and f*>>0.01.Such haloes collapse successively from 1-2 sigma peaks in LambdaCDM Gaussiandensity perturbations as time progresses. These dwarf galaxies can probablyenrich low and high-density regions of intergalactic space with metals to10^-3-10^-2 Zsun as they collapse at z~8 and z<5 respectively. They also may beable to provide adequate turbulent energy to prevent the collapse of othernearby halos, as well as to significantly broaden Lyman-alpha absorption linesto v_rms~20-40 km/s. We compute the timescales for the next starbursts if gasfreely falls back after a starburst, and find that, for star formationefficiencies as low as f*<0.01, the next starburst should occur in less thanhalf the Hubble time at the collapse redshift. This suggests that episodic starformation may be ubiquitous in dwarf galaxies.Comment: Accepted for ApJ v613, 60 pages, 15 figure