Friday

Rotation curves are a major tool for studying the distribution of mass within galaxies. In particular, their shapes provide fundamental constraints on the fraction of dark matter within galaxies. Recent results based on the analysis of average rotation curves suggest that galaxies at cosmic noon have a negligible dark matter fraction. While potentially dependent on the stacking technique adopted, these results might pose challenges to lambda-CDM models if confirmed. Analysis of the rotation curves in distant galaxies on an individual basis are therefore needed.

Integral Field Unit (IFU) observations are the essential tool for measuring dark matter fractions, as these can provide the full kinematic information required to derive accurate rotation curves and study the dynamical mass distribution in galaxies.

In my talk, I will show new results from KURVS, a Large Programme that exploits the combined IFU and multiplexing capabilities of KMOS to obtain rotation curves of z~1.5 individual galaxies out to large radii, owing to ~100 hours of integration time at the Very Large Telescope. I will discuss how the unprecedented signal-to-noise ratio of these Halpha maps allows us to provide robust constraints on the shape of individual rotation curves up to ~15 kpc.

These high-quality rotation curves show flat or rising profiles, in broad agreement with predictions from lambda-CDM models.