Speaker
Description
Understanding how galaxies evolved from turbulent compact systems to stable rotating discs remains a fundamental question in extragalactic astronomy. Studies of galaxy kinematics at z<3 have painted a picture where most star-forming galaxies exhibit disc-like kinematics that fuel an inside-out growth of galaxies and drive scaling relations between various properties such as star formation rate and metallicity. With the arrival of the James Webb Space Telescope (JWST) and the unprecedented sensitivity and resolution of its Near Infrared Camera (NIRCam), we are now able to push this analysis to higher redshifts well into the Epoch of Reionisation. NIRCam’s grism mode yields 2D spectra of every galaxy in the field of view of the instrument, allowing for the study of the emission lines of distant star-forming galaxies on spatially resolved scales. Harnessing this powerful instrument, I have developed a novel tool, GEKO (Grism Emission-line Kinematics tOol), which forward models and fits grism data using Bayesian inference to recover galaxy kinematics and intrinsic emission line maps.
In this talk, I will present GEKO and its first applications to H-alpha and OIII emitters (at redshifts z=5-6.5 and z=7-8 respectively) in the FRESCO survey, showing how the combination of this tool and the large surveys obtained with JWST will allow us to paint the first picture of galaxy kinematics and disc formation at high redshifts. I will then present a more complete analysis of a sub-sample of FRESCO Halpha emitters in the z=5.5-6.5 range that have OIII and Hbeta lines falling in the CONGRESS survey. In fact, with the combination of these two datasets, we were able to compute star-formation rate and metallicity gradients for these galaxies, shedding light on the link between the spatially resolved fundamental metallicity relation (FMR) constraints and galaxy kinematics. Finally, I will discuss the implications of this comprehensive study for our understanding of the baryon cycle at high-redshift and its impact on the properties of these ionising sources.
