Mass Assembly of High-z Galaxies with MASSIV

TL;DR

The MASSIV survey studied 84 distant star-forming galaxies at redshifts 0.8 to 1.9, revealing their dynamical states, merger activity, and metallicity gradients to understand galaxy evolution during this epoch.

Contribution

This study provides the first comprehensive analysis of galaxy kinematics, mergers, and metallicity gradients in a representative sample at z~1.

Findings

42% of galaxies are rotating disks

About 58% show complex kinematics

Positive metallicity gradients observed

Abstract

MASSIV (Mass Assembly Survey with SINFONI in VVDS) is a sample of 84 distant star-forming galaxies observed with the SINFONI Integral Field Unit (IFU) on the VLT. These galaxies are selected inside a redshift range of 0.8 < z < 1.9, i.e. where they are between 3 and 5 billion years old. The sample aims to probe the dynamical and chemical abundances properties of representative galaxies of this cosmological era. On the one hand, close environment study shows that about a third of the sample is involved in major mergers. On the other hand, kinematical analysis revealed that 42% of the sample is rotating disks, in accordance with higher redshift samples. The remaining 58% show complex kinematics, suggesting a dynamical support based on dispersion, and about half of these galaxies is involved in major mergers. Spheroids, unrelaxed merger remnants, or extremely turbulent disks might be an explanation for such a behavior. Furthermore, the spatially resolved metallicity analysis reveals positive gradients, adding a piece to the puzzle of galaxies evolution scenarios.