Kavli Affiliate: Mark Vogelsberger
| First 5 Authors: Zihao Wang, Xuejian Shen, Mark Vogelsberger, Hui Li, Rahul Kannan
| Summary:
Star formation in galaxies is inherently complex, involving the interplay of
physical processes over a hierarchy of spatial scales. In this work, we
investigate the connection between global (galaxy-scale) and local
(cloud-scale) star formation efficiencies (SFEs) at high redshifts ($zgtrsim
3$), using the state-of-the-art cosmological zoom-in simulation suite
THESAN-ZOOM. We find that the galaxy-scale average SFE, $langle epsilon^{rm
gal}_{rm ff} rangle$, scales with $M_{rm halo}^{1/3},(1+z)^{1/2} sim
V_{rm vir}$, consistent with expectations from feedback-regulated models. On
cloud scales, we identify giant molecular clouds (GMCs) in a broad sample of
high-redshift starbursts spanning a wide range of halo masses and redshifts.
Star formation in these systems is predominantly hosted by filamentary GMCs
embedded in a dense and highly turbulent interstellar medium (ISM). GMCs
exhibit remarkably universal properties, including mass function, size,
turbulence, and surface density, regardless of the environment in which they
are identified. The global gas depletion time (and the Kennicutt-Schmidt
relation) is determined by the GMC mass fraction in the ISM, while the
cloud-scale SFE shows little variation. In particular, we find a nearly
constant gas surface density of $Sigma_{rm GMC} approx 70,{rm
M}_{odot},{rm pc}^{-2}$ across different host galaxies. Nevertheless, we
identify two regimes where phases with high SFE can arise. First, stars may
form efficiently in the shock fronts generated by feedback from a preceding
starburst. Second, the increasing background dark matter surface density with
redshift may contribute to the gravitational potential of clouds at $z gtrsim
8$ and confine them in high-SFE phases over extended periods.
| Search Query: ArXiv Query: search_query=au:”Mark Vogelsberger”&id_list=&start=0&max_results=3