articleMonthly Notices of the Royal Astronomical SocietyMay 25, 2023Closed access

Efficient formation of massive galaxies at cosmic dawn by feedback-free starbursts

University of California, Santa Cruz · Hebrew University of Jerusalem · +1 more institution

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Abstract

ABSTRACT JWST observations indicate a surprising excess of luminous galaxies at z ∼ 10 and above, consistent with efficient conversion of the accreted gas into stars, unlike the suppression of star formation by feedback at later times. We show that the high densities and low metallicities at this epoch guarantee a high star formation efficiency (SFE) in the most massive dark-matter haloes. Feedback-free starbursts (FFBs) occur when the free-fall time is shorter than ∼$1\, {\rm Myr}$, below the time for low-metallicity massive stars to develop winds and supernovae. This corresponds to a characteristic density of ∼$3\!\times \!10^3\, {\rm cm}^{-3}$. A comparable threshold density permits a starburst by allowing…

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