Adaptive Optics Imaging of Lyman Break Galaxies as Progenitors of Spheroids in the Local Universe

TL;DR

This study uses adaptive optics imaging to analyze the stellar mass distribution of z~3 Lyman Break Galaxies, revealing their potential evolution into spheroids in the local universe through mergers.

Contribution

It provides high-resolution K-band observations of LBGs, showing their disk-like structures and dense stellar mass profiles, suggesting a pathway to spheroid formation.

Findings

K-band peaks show offsets from optical images in some LBGs.

z~3 LBGs and DRGs have flat, disk-like profiles with n<2.

Surface stellar mass densities are 3-6 times higher than local disk galaxies.

Abstract

In order to reveal the stellar mass distribution of z~3 galaxies, we are conducting deep imaging observations of U-dropout Lyman Break Galaxies (LBGs) with Adaptive Optics (AO) systems in K-band, which corresponds to rest-frame V-band of z~3 galaxies. The results of the Subaru intensive-program observations with AO36/NGS/IRCS indicate that 1) the K-band peaks of some of the LBGs brighter than K=22.0 mag show significant offset from those in the optical images, 2) the z~3 Mv* LBGs and serendipitously observed Distant Red Galaxies (DRGs) have flat profiles similar to disk galaxies in the local universe (i.e., Sersic with n<2), and 3) the surface stellar mass densities of the Mv* LBGs are 3-6 times larger than those of disk galaxies at z=0-1. Considering the lack of n>2 systems among the luminous z~3 LBGs and DRGs, and their strong spatial clustering, we infer that the dense n<2 disk-like structures evolve into the n>2 spheroids of nearby galaxies through relaxations due to major merger events.