Ultra deep sub-kpc view of nearby massive compact galaxies

TL;DR

This study uses ultra-deep, high-resolution imaging to analyze nearby massive compact galaxies, revealing their detailed structure, lack of faint extended envelopes, and similarities to high-redshift counterparts, providing insights into galaxy formation.

Contribution

First detailed high-resolution structural analysis of nearby massive compact galaxies, linking their properties to early universe galaxy formation processes.

Findings

No faint extended envelope detected in these galaxies.

Galaxies are elongated and resemble S0 types.

Shared properties with high-z compact galaxies, including stellar age.

Abstract

Using Gemini North telescope ultra deep and high resolution (sub-kpc) K-band adaptive optics imaging of a sample of 4 nearby (z~0.15) massive (~10^{11}M_sun) compact (R<1.5 kpc) galaxies, we have explored the structural properties of these rare objects with an unprecedented detail. Our surface brightness profiles expand over 12 magnitudes in range allowing us to explore the presence of any faint extended envelope on these objects down to stellar mass densities ~10^{6} M_sun/kpc^{2} at radial distances of ~15 kpc. We find no evidence for any extended faint tail altering the compactness of these galaxies. Our objects are elongated, resembling visually S0 galaxies, and have a central stellar mass density well above the stellar mass densities of objects with similar stellar mass but normal size in the present universe. If these massive compact objects will eventually transform into normal size galaxies, the processes driving this size growth will have to migrate around 2-3x10^{10}M_sun stellar mass from their inner (R<1.7 kpc) region towards their outskirts. Nearby massive compact galaxies share with high-z compact massive galaxies not only their stellar mass, size and velocity dispersion but also the shape of their profiles and the mean age of their stellar populations. This makes these singular galaxies unique laboratories to explore the early stages of the formation of massive galaxies.