LARS XV. Spatially resolved Halpha kinematics

We calculate shearing velocities, v_s, and intrinsic velocity dispersions, {sigma}_v_ (empirically corrected for beam-smearing effects), as global kinematical measures for each galaxy. The sample is characterised by highly turbulent motions (30km/s<~{sigma}_v_<~80km/s) and more than half of the sources show dispersion-dominated kinematics. We uncover clear trends between Ly{alpha} observables and global kinematical statistics: EW_Ly{alpha}_ and L_Ly{alpha}_ correlate with {sigma}_v_, while f_esc_ anti-correlates with v_s_ and v_s_/{sigma}_v_.

Moreover, we find, that galaxies with EW_Ly{alpha}_>=20{AA} are characterised by higher {sigma}_v_ and lower v_s_/{sigma}_v_ than galaxies below this threshold. We discuss the statistical importance of v_s_, {sigma}_v_, and v_s_/{sigma}_v_ for regulating the Ly{alpha} observables in comparison to other galaxy parameters. It emerges that {sigma}_v_ is the dominating parameter for regulating EW_Ly{alpha}_ and that is as important as nebular extinction, gas covering fraction, and ionising photon production efficiency in regulating f_esc_.

A simple scenario where the starburst age is simultaneously regulating turbulence, EW_Ly{alpha}_, and f_esc_ is not supported by our observations. However, we show that the small-scale distribution of dust appears to be influenced by turbulence in some galaxies. In support of our observational result, we discuss how turbulence is theoretically expected to play a significant role in modulating f_esc_.