VLT/SINFONI Integral Field Spectroscopy of The Super-antennae

TL;DR

This study uses integral field spectroscopy to analyze the molecular and ionized gas in the ULIRG IRAS 19254-7245, revealing details about its kinematics, excitation mechanisms, and the presence of an embedded AGN.

Contribution

First detailed integral field spectroscopic analysis of the ULIRG IRAS 19254-7245, providing insights into its gas excitation, kinematics, and nuclear activity.

Findings

H- and K-band spectroscopy reveals a warped disc with specific orientation.

Detection of high-ionization lines indicating active galactic nucleus presence.

H2 excitation by UV fluorescence in the core and shock excitation further out.

Abstract

We present the results of H- and K-band VLT/SINFONI integral field spectroscopy of the ULIRG IRAS 19254-7245 (The Super-antennae), an interacting double galaxy system containing an embedded AGN. Deep K-band spectroscopy reveals PaAlpha arising in a warped disc with position angle of 330 degree and an inclination i=40-55 degree. The kinemetric parameters derived for H2 are similar to PaAlpha. Two high-ionization emission lines, [SiVI] and [AlIX], are detected and we identify as [NiII] the line observed at 1.94 micron. Diluting non-stellar continuum, which was previously detected, has decayed, and the H-band continuum emission is consistent with pure stellar emission. Based on H2 emission line ratios it is likely that at the central 1-kpc region H2 is excited by UV fluorescence in dense clouds while shock excitation is dominant further out. This scenario is supported by very low PaAlpha to H2 line ratio detected outside the nuclear region and non-thermal ortho/para ratios (~2.0 - 2.5) close to the nucleus.