Thiago Goncalves (Caltech)

Ionized Gas in Lyman Break Analogs: Probing Extreme Star-Forming Galaxies at High Resolution

Supercompact ultraviolet-luminous galaxies (ScUVLGs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming objects in the low-redshift universe (z~0.2), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman-break galaxies (LBGs), motivating the detailed study of ScUVLGs as potential local analogs to this high-redshift galaxy population. Strong hydrogen emission lines and compact sizes make ScUVLGs ideal candidates for integral-field spectrography. We present results for 12 ScUVLGs observed with Keck/OSIRIS with an AO-assisted spatial resolution of less than 200pc. We detect satellite companions, diffuse emission and velocity shear, all with high signal-to-noise ratios. We artificially redshift our data to z ~ 2.2 to allow for a direct comparison with observations of high-z LBGs and find striking similarities between both samples. This suggests that the same physical processes may be responsible for the observed properties of star forming galaxies in the early universe. We also find a strong correlation of observable properties with stellar mass, in which more massive galaxies show greater resemblance to a disk-like structure. We believe this indicates an evolutionary sequence in which galaxies settle into a colder dynamical structure while consuming the gas reservoir to form stars.