An OSIRIS Study of the Gas Kinematics in a Sample of UV-Selected Galaxies: Evidence of "Hot and Bothered" Starbursts in the Local Universe

Abstract

We present data from Integral Field Spectroscopy for three supercompact UV-Luminous Galaxies (ScUVLGs). As nearby (z ~ 0.2) compact (R ₅₀ ~ 1-2 kpc) bright Paschen-α sources, with unusually high star formation rates (SFR = 3-100 M _sun yr^-1), ScUVLGs are an ideal population for studying detailed kinematics and dynamics in actively star-forming galaxies. In addition, ScUVLGs appear to be excellent analogs to high-redshift Lyman Break Galaxies (LBGs), and our results may offer additional insight into the dynamics of LBGs. Previous work by our team has shown that the morphologies of these galaxies exhibit tidal features and companions, and in this study we find that the dynamics of ScUVLGs are dominated by disturbed kinematics of the emission line gas—suggesting that these galaxies have undergone recent feedback, interactions, or mergers. While two of the three galaxies do display rotation, v/σ<1—suggesting dispersion-dominated kinematics rather than smooth rotation. We also simulate how these observations would appear at z ~ 2. Lower resolution and loss of low surface brightness features cause some apparent discrepancies between the low-z (observed) and high-z (simulated) interpretations and quantitatively gives different values for v/σ, yet simulations of these low-z analogs manage to detect the brightest regions well and resemble actual high-z observations of LBGs.