Kavli Affiliate: Mark Vogelsberger
| First 5 Authors: Yang Ni, Hui Li, Mark Vogelsberger, Laura V. Sales, Federico Marinacci
| Summary:
In this work, we trace the complete life cycle of individual GMCs in
high-resolution Milky Way-mass galaxy simulations to determine how different
stellar feedback mechanisms and galactic-scale processes govern cloud
lifetimes, mass evolution, and local star formation efficiency (SFE). We
identify GMCs in simulated galaxies and track their evolution using cloud
evolution trees. Via cloud evolution trees, we quantify the lifetimes and SFE
of GMCs. We further apply our diagnostics on a suite of simulations with
varying star formation and stellar feedback subgrid models and explore their
impact together with galactic environments to the GMC life cycles. Our analysis
reveals that GMCs undergo dynamic evolution, characterized by continuous gas
accretion, gravitational collapse, and star formation, followed by disruption
due to stellar feedback. The accretion process sustains the gas content
throughout most of the GMC life cycles, resulting in a positive correlation
between GMC lifetimes and their maximum masses. The GMC lifetimes range from a
few to several tens of Myr, with two distinct dynamical modes: (1) GMCs near
the galactic center experience strong tidal disturbances, prolonging their
lifetimes when they remain marginally unbound; (2) those in the outer regions
are less affected by tides, remain gravitationally bound, and evolve more
rapidly. In all model variations, we observe that GMC-scale SFE correlates with
the baryonic surface density of GMCs, consistent with previous studies of
isolated GMCs. Additionally, we emphasize the critical role of galactic shear
in regulating GMC-scale star formation and refine the correlation between local
SFE and surface density by including its effects. These findings demonstrate
how stellar feedback and galactic-scale dynamics jointly shape GMC-scale star
formation in realistic galactic environments.
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