Absorption features of high-redshift galactic winds

Abstract

The environment of high-redshift galaxies is characterized by both wind-driven outflowing gas and gravitationally infalling streams. To investigate such galaxy-IGM interplay we have generated synthetic optical absorption line spectra piercing the volume surrounding a starbursting analog of a Lyman Break Galaxy selected in a z ≈ 3 output from a SPH simulation, including a detailed treatment of mechanical feedback from winds. Distributions for several observable species (Hi, Ciii, Civ, Siii, Siiii, Siiv, Ovi, Ovii, and Oviii) have been derived by post-processing the simulation outputs. The hot wind material is characterized by the presence of high-ionization species such as Ovi, Ovii, and Oviii (the latter two observable only in X-ray bands); the colder (T < 10^5.5 K) infalling streams can be instead identified by the combined presence of Siii, Siiii, and Ciii optical absorption together with Ovi that surrounds the cooler gas clumps. Considering both line profile and Pixel Optical Depth analysis of the synthetic spectra. We conclude that it may be difficult to clearly identify wind-blowing galaxies and their complex gaseous environment at high redshift in optical QSO absorption-line spectra based solely on the observed ion absorption patterns.