An $H\alpha$ Imaging Survey of the all (Ultra-)Luminous Infrared Galaxies at $Dec. \ge -30^{\circ}$ in the GOALS Sample

TL;DR

This study provides a comprehensive $H\alpha$ imaging survey of 148 (U)LIRGs from the GOALS sample, revealing how galaxy interactions influence star formation distribution and infrared properties.

Contribution

It presents the first complete $H\alpha$ imaging analysis of a well-defined (U)LIRG sample, linking star formation morphology to galaxy interaction stages.

Findings

Star-forming regions become more compact with advanced merging stages.

Higher infrared luminosity correlates with more disturbed galaxy morphology.

Warmer IR colors are associated with more advanced mergers.

Abstract

This paper presents the result of $H\alpha$ imaging for luminous infrared galaxies (LIRGs) and ultra-luminous infrared galaxies (ULIRGs). \textbf{It is } a \textbf{complete subsample of Great Observatories All-sky LIRG Survery (GOALS) with $Dec. \ge -30^{\circ}$}, \textbf{and} consists 148 galaxies with $log(L_{IR}/L_{\odot}) \ge 11.0$. All the $H\alpha$ images were carried out using the 2.16-m telescope \textbf{at the Xinglong Station of the} National Astronomy Observatories, Chinese Academy of Sciences\textbf{ (NAOC),} during the year from 2006 to 2009. We obtained pure $H\alpha$ luminosity for each galaxy and corrected the luminosity for $[NII]$ emission, filter transmission and extinction. We also classified these galaxies based on their morphology and interaction. We found that the distribution of star-forming \textbf{regions} in these galaxies is related to this classification. As the merging process advanced, these galaxies tend to have a more compact distribution of star-forming region, higher \textbf{$L_{IR}$} and warmer IR-color ($f_{60}/f_{100}$). \textbf{These} results imply that the degree of dynamical disturbance plays an important role in determining the distribution of star-forming region.