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Title: How did galaxies accumulate so much dust within one billion years?
Plain: Some galaxies seen less than a billion years after the Big Bang already contain tens of millions of Suns' worth of dust. Supernovae alone seem unable to make that much in the time available.
Precise: Galaxies and quasar hosts at $z > 6$ contain dust masses of about $1\mathrm{e}7 \text{ to } 1\mathrm{e}8\,M_{\mathrm{sun}}$. Determine the dominant source: supernova condensation (net yields after reverse-shock destruction of about $0.01 \text{ to } 0.1\,M_{\mathrm{sun}}$ per supernova), asymptotic giant branch stars, or grain growth in the interstellar medium, and the required growth timescale.
Settled by: Dust-to-gas and dust-to-metal ratios for a large sample at $z > 6$ with independent dust temperatures, compared with chemical evolution models.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: open
Status note: (empty)
Posed since: (empty)