Mauro Giavalisco (Uni Massachusetts)

The Evolution of Galaxies: Quenching and Structural Transformations
Wann Am 10.01.2019 von 14:30 bis 15:30
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  • Kolloquium
Wo SH Lecture Hall
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Both in the present-day Universe and earlier on, approximately z~3, we have documented profound structural differences between quiescent and star-forming galaxies. The former are predominantly dynamically hot systems and have spheroidal morphology, the latter host their star formation in rotating disks (thinner and colder today, apparently thicker and hotter at high redshifts). At high redshift (z>1) and up to when quiescent systems can be reliably identified (z~3-4), dynamical information becomes more uncertain, at least in passive systems, but this dicothomy seems to persist at least morphologically. The recent discovery that disks at high redshift (2<z<3) might be strongly baryon-dominated, while their z=0 counterparts with comparable mass are dark-matter dominated, appears to add to the puzzle. Do galaxies transform their structures, both baryonic and dark, as they quench? And why? So far, galaxy transformations at high redshift (z>2) have mostly focused on the growth of the core stellar mass density, e.g. at r<1 kpc. These very central volumes are the sink of all the dissipative processes that take place during star formation and while they inform us, in an integral way, on the accretion history of the galaxy of both the dissipative (gas, via cold and hot accretion) and non-dissipative (stars and dark matter, via adiabatic contractions) components, they are baryon-dominated even in today disks and do not contain information on if and how the large-scale structure of galaxies evolves, dark matter included. Here I show novel evidence that the spatial distribution of the bulk of the stars (rest-frame from 4000 to 6400 Ang), i.e. one of the two non-dissipative components, of massive galaxies at 1.5<z<3 systematically evolves with time as the galaxies form stars (primarily) and perhaps even after they quench.