The fate of Lyman photons in local Starburst: new ACS/HST images

We review the imaging and spectroscopic properties of the Lyman alpha emission in starburst galaxies. The Lyman alpha photons escape is largely driven by kinematical and orientation effects related to the presence of large scale expanding shells of neutral hydrogen. The various Lyman alpha profiles can be linked to the evolutionary state of the starburst. Our recent Lyman alpha imaging study using the HST-ACS is presented here: it highlights the presence of diffuse extended emission of low intensity leaking out the diffuse HI components. The similarities with the line profiles observed on high redshift galaxies is an important fact that cautions the use of Lyman alpha to derive the cosmic star formation rate and constrains the search for high redshift galaxies.