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Accueil > Seminar on 2021.03.01 by Eduardo (...) > Cool Gas Flows Around Star-Forming (...)

Cool Gas Flows Around Star-Forming Galaxies at 0.3 < z < 1.4

Kate Rubin (Max-Planck-Institut für Astronomie, Heidelberg)

Galactic-scale outflows power the “baryon cycle” : they recycle gas from star-forming regions into the circumgalactic medium, and likely play a key role in determining the frequency and morphology of galactic gas accretion (or re-accretion). However, the relationship between outflow properties and the star formation activity in distant galaxies remains poorly constrained. In addition, empirical evidence for the inflow of gas onto distant systems has remained elusive. We present an analysis of absorption line profiles for the MgII 2796,2803 and FeII 2586,2600 transitions in individual spectra of ∼100 star-forming galaxies at 0.3 < z < 1.4 selected from the GOODS fields and the Extended Groth Strip. We identify outflows (inflows) of cool (T∼104 K) gas via the blueshift (redshift) of the absorption lines. We detect outflows in ∼65% of this sample, and find evidence for gas inflow into at least six of the galaxies. Using high resolution HST/ACS imaging to estimate galaxy orientation, we find that the detection rate of outflows increases with decreasing galaxy inclination. Moreover, five of the six bona-fide inflow galaxies have disk-like morphologies and are viewed nearly edge-on, suggesting that inflow is more likely to occur along the disk plane. We identify a weak positive correlation between the equivalent width of absorption due to outflows and host galaxy star formation rate (SFR), but find no correlation between outflow velocity and SFR or SFR surface density. Finally, we find that the measured outflow velocities do not exceed the escape velocity for most of the galaxies in our sample, suggesting that the gas will likely be re-accreted as in a galactic fountain.