The evolution of merger fraction of galaxies at <i>z</i> &lt; 0.6 depending on the star formation mode in the <i>AKARI</i> NEP-Wide Field
Eunbin Kim, Ho Seong Hwang, Woong-Seob Jeong, Seong Jin Kim, D. Burgarella, Tomotsugu Goto, T. Hashimoto, Young-Soo Jo, Jong Chul Lee, Matthew A. Malkan, Chris Pearson, Hyunjin Shim, Yoshiki Toba, Simon C-C Ho, D. Santos, Hiroyuki Ikeda, Helen K. Kim, T. Miyaji, Hideo Matsuhara, Nagisa Oi, Toshinobu Takagi, Ting-Wen Wang
Abstract
ABSTRACT We study the galaxy merger fraction and its dependence on star formation mode in the 5.4 deg2 of the North Ecliptic Pole-Wide Field. We select 6352 galaxies with AKARI 9 $\mu$m detections, and identify mergers among them using the Gini coefficient and M20 derived from the Subaru/Hyper Suprime-Cam (HSC) optical images. We obtain the total infrared luminosity and star formation rate of galaxies using the spectral energy distribution templates based on one band, AKARI$9\, \mu$m. We classify galaxies into three different star formation modes (i.e. starbursts, main-sequence, and quiescent galaxies) and calculate the merger fractions for each. We find that the merger fractions of galaxies increase with redshift at z &lt; 0.6. The merger fractions of starbursts are higher than those of main-sequence and quiescent galaxies in all redshift bins. We also examine the merger fractions of far-infrared-detected galaxies that have at least one detection from Herschel/Spectral and Photometric Imaging Receiver (SPIRE). We find that Herschel-detected galaxies have higher merger fraction compared to non-Herschel-detected galaxies, and both Herschel-detected and non-Herschel-detected galaxies show clearly different merger fractions depending on the star formation modes.