KROSS: The KMOS Redshift One Spectroscopic Survey
I will present results from the KMOS Redshift One Spectroscopic Survey (KROSS). Using the K-band Multi-object Spectrograph (KMOS) at the Very Large Telescope (VLT), KROSS has gathered integral-field data for ~800 star-forming galaxies at a redshift z~1, when the universe was roughly half its current age and forming the bulk of its stars. KROSS aims to study the spatially-resolved dynamics, star formation properties and metallicities of those middle-aged galaxies. First, I will quantify the dynamical state of the galaxies, thus constraining their likely mass growth mechanisms (e.g. mergers versus secular evolution), painting a picture of galaxies that are both gas-rich and highly turbulent. Second, I will describe the properties of the galaxies departing from the star formation main sequence, revealing that star formation in highly star-forming galaxies is also more concentrated and arises from lower metallicity gas. Third, I will present the observed and baryonic Tully-Fisher (luminosity - rotation velocity) relation, thus constraining the mass-to-light ratios and luminous+dark masses of the galaxies. Fourth, by degrading and analogously analysing integral-field data of hundreds of local galaxies from the Sydney-AAO Multi-object Integral-field Spectrograph (SAMI) survey, I will derive a comparison Tully-Fisher relation at z=0, thus constraining the luminous+dark mass growth of disk galaxies over the last 7 billions years. Lastly, I will probe the behaviour of the galaxy rotation curves at large radii, showing that contrary to recent claims the curves remain flat or slightly rising in the vast majority of galaxies. This in turn suggests that the galaxies' dark matter haloes were already in place at z~1, supporting the cold dark matter (CDM) paradigm of galaxy formation.
Date: Thursday, 10 January 2019 Time: 11:30 Where: Université de Montréal Pavillon Roger-Gaudry, Local D-460 Contact: René Doyon