The elaboration of spiral galaxies: morpho-kinematics analyses of their progenitors with IMAGES

TL;DR

This study uses advanced integral field spectroscopy and multi-wavelength observations to analyze the morpho-kinematics of distant galaxy progenitors, revealing the significant role of mergers and disk rebuilding in galaxy evolution.

Contribution

It provides detailed kinematic and morphological analyses of 100 massive galaxies at intermediate redshifts, supporting the hierarchical galaxy formation scenario.

Findings

Half of the galaxies 6 Gyrs ago had peculiar velocity fields.

Merger processes significantly influence galaxy evolution.

Disk rebuilding is crucial for the formation of present-day spirals.

Abstract

The IMAGES project aims at measuring the velocity fields of a representative sample of 100 massive galaxies at z=0.4-0.75, selected in the CDFS, the CFRS and the HDFS fields. It uses the world-unique mode of multiple integral field units of FLAMES/ GIRAFFE at VLT. The resolved-kinematics data allow us to sample the large scale motions at ~ few kpc scale for each galaxy. They have been combined with the deepest HST/ACS, Spitzer (MIPS and IRAC) and VLT/FORS2 ever achieved observations. Most intermediate redshift galaxies show anomalous velocity fields: 6 Gyrs ago, half of the present day spirals were out of equilibrium and had peculiar morphologies. The wealth of the data in these fields allow us to modelize the physical processes in each galaxy with an accuracy almost similar to what is done in the local Universe. These detailed analyses reveal the importance of merger processes, including their remnant phases. Together with the large evolution of spiral properties, this points out the importance of disk survival and strengthens the disk rebuilding scenario. This suggests that the hierarchical scenario may apply to the elaboration of disk galaxies as it does for ellipticals.