THE VLT SINFONI Mg II PROGRAM FOR LINE EMITTERS (SIMPLE). II. BACKGROUND QUASARS PROBING Z similar to 1 GALACTIC WINDS
Résumé
The physical properties of galactic winds are of paramount importance for our understanding of galaxy formation. Fortunately, they can be constrained using background quasars passing near star-forming galaxies (SFGs). From the 14 quasar-galaxy pairs in our Very Large Telescope (VLT)/SINFONI Mg II Program for Line Emitters sample, we reobserved the 10 brightest galaxies in Ha with the VLT/SINFONI with 0”.7 seeing and the corresponding quasar with the VLT/UVES spectrograph. Applying geometrical arguments to these 10 pairs, we find that four are likely probing galactic outflows, three are likely probing extended gaseous disks, and the remaining three are not classifiable because they are viewed face-on. In this paper we present a detailed comparison between the line-of-sight kinematics and the host galaxy emission kinematics for the pairs suitable for wind studies. We find that the kinematic profile shapes (asymmetries) can be well reproduced by a purely geometrical wind model with a constant wind speed, except for one pair (toward J2357-2736) that has the smallest impact parameter b = 6 kpc and requires an accelerated wind flow. Globally, the outflow speeds are similar to 100 km s(-1) and the mass ejection rates (or M-out) in the gas traced by the low-ionization species are similar to the star formation rate (SFR), meaning that the mass loading factor, eta = M-out /SFR, is approximate to 1.0. The outflow speeds are also smaller than the local escape velocity, which implies that the outflows do not escape the galaxy halo and are likely to fall back into the interstellar medium.