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Seminars at FGG

The role of star-formation driven outflows in galaxy evolution: data are needed!

Speaker: Lucia Guaita (Stockholm University)

Date and time: 2014-02-27 11:30

Star-forming galaxies are frequently characterized by strong Lyman alpha line in emission. Lyman alpha photons are easily absorbed by dust, generally not-negligible in star-forming regions. Special kinematics and neutral Hydrogen (HI) conditions of the interstellar medium are the most plausible ways Lyman alpha photons can escape even moderately-dusty galaxies. To quantify the interstellar medium kinematics, we focus on the measurement of the velocity offsetsbetween rest-frame UV, tracing HI flows, and optical, representing galaxy systemic redshifts, emission lines. The star-forming galaxies at z~2-3 we studied typically show velocity offsets of the order of 70-270 km/sec. However, star-forming galaxies with weak Lyman alpha emission tend to present velocity offsets of several hundreds of km/sec. If this offsets are really related to strong star-formation driven outflows, we could expect them to play a significant role in galaxy evolution. For example they could remove gas and metals from the interstellar medium preventing subsequent phases of star formation. Rest-frame UV together with rest-frame optical data are needed to carry on this hypothesis. I will focus on our recent survey and on how DOLORES data, I will obtain next week, would be the icing on the cake.