3D spectroscopy with VLT/GIRAFFE: I- the true Tully Fisher relationship at z~0.6

TL;DR

This study uses VLT/GIRAFFE integral field spectroscopy to analyze the Tully-Fisher relationship at z~0.6, revealing that most galaxies have perturbed kinematics, which affects previous measurements of its evolution.

Contribution

First detailed analysis of the Tully-Fisher relation at intermediate redshift using integral field spectroscopy, highlighting the impact of complex kinematics on its observed evolution.

Findings

Only 35% of galaxies are rotating disks with stable kinematics.

The Tully-Fisher relation's slope, zero point, and scatter show no evolution since z=0.6.

Large scatter in previous studies is due to galaxies with disturbed kinematics.

Abstract

A precise derivation of the evolution of the Tully Fisher is crucial to understand the interplay between dark matter and baryonic matter in cosmological models, Using 15 deployable integral field units of FLAMES/GIRAFFE at VLT, we have recovered the velocity fields of 35 galaxies at intermediate redshift (0.4 < z < 0.75). This facility is able to recover the velocity fields of almost all the emission line galaxies with Iab <=22.5 and W_0(OII)>=15A In our sample, we find only 35% rotating disks. These rotating disks produce a Tully-Fisher relationship (stellar mass or M_K versus V_max) which has apparently not evolved in slope, zero point and scatter since z=0.6. The only evolution found is a brightening of the B band luminosity of a third of the disks, possibly due to an enhancement of the star formation. The very large scatters found in previously reported Tully-Fisher relationships at moderate redshifts are caused by the numerous (65%) galaxies with perturbed or complex kinematics. Those galaxies include minor or major mergers, merger remnants and/or inflow/outflows and their kinematics can be easily misidentified by slit spectroscopy. Their presence suggests a strong evolution in the dynamical properties of galaxies during the last 7 Gyrs.