A SINFONI integral field spectroscopy survey for galaxy counterparts to damped Lyman α systems - II. Dynamical properties of the galaxies towards Q0302-223 and Q1009-0026

Details of the processes through which galaxies convert their gas into stars need to be studied in order to obtain a complete picture of galaxy formation. One way to tackle these phenomena is to relate the HI gas and the stars in galaxies. Here, we present dynamical properties of damped and subdamped Lyman alpha (DLA) systems identified in H alpha emission with VLT/SINFONI at near-infrared wavelengths. While the DLA towards Q0302 - 223 is found to be dispersion-dominated, the sub-DLA towards Q1009 - 0026 shows clear signatures of rotation. We use a proxy to circular velocity to estimate the mass of the halo in which the sub-DLA resides and find M-halo = 10(12.6) M-circle dot. We also derive dynamical masses of these objects, and find M-dyn = 10(10.3) and 10(10.9) M-circle dot. For one of the two systems (towards Q0302 - 223), we are able to derive a stellar mass of M-* = 10(9.5) M-circle dot from a spectral energy distribution fit. The gas fraction in this object is one-third, comparable to similar objects at these redshifts. Our work illustrates that detailed studies of quasar absorbers can offer entirely new insights into our knowledge of the interaction between stars and the interstellar gas in galaxies.