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KROSS: The KMOS Redshift One Spectroscopic Survey

Speaker:Prof. Martin Bureau
Affiliation:University of Oxford
Date:May 25, 2017 (Thursday)
Time:2:30 p.m.
Venue:Room 522, 5/F, Chong Yuet Ming Physics Building, HKU


I will present results from the KMOS Redshift One Spectroscopic Survey (KROSS). Using the Kband 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. Last, 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. This unique comparison also highlights that the systematic effects associated with sample selection and analysis methods are as large as the effects expected from cosmological evolution, and thus that most other results can safely be ignored.
Coffee and tea will be served 20 minutes prior to the seminar.

Anyone interested is welcome to attend.