Optical IFU Observations of GOALS Sample with KOOLS-IFU on Seimei Telescope: Initial results of 9 U/LIRGs at $z <$ 0.04

TL;DR

This study uses IFU observations to analyze ionized gas and AGN activity in 9 local U/LIRGs, revealing merger-stage-dependent outflow strengths that suggest galaxy mergers influence black hole growth.

Contribution

First spatially-resolved IFU study of local U/LIRGs covering various merger stages, linking outflow strength to merger progression.

Findings

AGN-driven outflows are stronger in galaxy centers.

Outflow strength increases with merger stage.

Galaxy mergers may promote black hole growth.

Abstract

We present ionized gas properties of 9 local ultra/luminous infrared galaxies (U/LIRGs) at $z <$ 0.04 through IFU observations with KOOLS-IFU on Seimei Telescope. The observed targets are drawn from the Great Observatories All-sky LIRG Survey (GOALS), covering a wide range of merger stages. We successfully detect emission lines such as H$\beta$, [OIII]$\lambda$5007, H$\alpha$, [NII]$\lambda\lambda$6549,6583, and [SII]$\lambda\lambda$6717,6731 with a spectral resolution of $R$ = 1500-2000, which provides (i) spatially-resolved ($\sim$200-700 pc) moment map of ionized gas and (ii) diagnostics for active galactic nucleus (AGN) within the central $\sim$3--11 kpc in diameter for our sample. We find that [OIII] outflow that is expected to be driven by AGN tends to be stronger (i) towards the galactic center and (ii) as a sequence of merger stage. In particular, the outflow strength in the late-stage (stage D) mergers is about 1.5 times stronger than that in the early-state (stage B) mergers, which indicates that galaxy mergers could induce AGN-driven outflow and play an important role in the co-evolution of galaxies and supermassive black holes.