Philip F. Hopkins, Alexander B. Gurvich, Xuejian Shen, Zachary Hafen, Michael Y. Grudic

| Summary:

[[{“value”:”As they grow, galaxies can transition from irregular/spheroidal with ‘bursty’
star formation histories (SFHs), to disky with smooth SFHs. But even in
simulations, the direct physical cause of such transitions remains unclear. We
therefore explore this in a large suite of numerical experiments re-running
portions of cosmological simulations with widely varied physics, further
validated with existing FIRE simulations. We show that gas supply,
cooling/thermodynamics, star formation model, Toomre scale, galaxy dynamical
times, and feedback properties do not have a direct causal effect on these
transitions. Rather, both the formation of disks and cessation of bursty star
formation are driven by the gravitational potential, but in different ways.
Disk formation is promoted when the mass profile becomes sufficiently
centrally-concentrated in shape (relative to circularization radii): we show
that this provides a well-defined dynamical center, ceases to support the
global ‘breathing modes’ which can persist indefinitely in less-concentrated
profiles and efficiently destroy disks, promotes orbit mixing to form a
coherent angular momentum, and stabilizes the disk. Smooth SF is promoted by
the potential or escape velocity (not circular velocity) becoming sufficiently
large at the radii of star formation that cool, mass-loaded
(momentum-conserving) outflows are trapped/confined near the galaxy, as opposed
to escaping after bursts. We discuss the detailed physics, how these conditions
arise in cosmological contexts, their relation to other correlated phenomena
(e.g. inner halo virialization, vertical disk ‘settling’), and observations.”}]] 

| Search Query: ArXiv Query: search_query=au:”Fangzhou Jiang”&id_list=&start=0&max_results=10

[[{“value”:”Read More“}]]