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Spectroscopically and spatially resolved optical line emission in the Superantennae (IRAS 19254−7245)


  • Based on observations collected at the European Organization for Astronomical Research in the Southern hemisphere, Chile [080.B-0085].



We present Visible Multi-Object Spectrograph integral-field spectroscopic observations of the ultraluminous infrared galaxy (ULIRG) pair IRAS 19254−7245 (the Superantennae). We resolve Hα, [N ii], [O i] and [S ii] emission both spatially and spectroscopically, and separate the emission into multiple velocity components. We identify spectral line emission characteristic of star formation associated with both galaxies, broad spectral line emission from the nucleus of the southern progenitor and potential outflows with shock-excited spectral features near both nuclei. We estimate that ≲10 per cent of the 24 μm flux density originates from star formation, implying that most of the 24 μm emission originates from the active galactic nuclei in the southern nucleus. We also measure a gas consumption time of ∼1 Gyr, which is consistent with other measurements of ULIRGs.