ASTRO
In the literature: open
How did galaxies accumulate so much dust within one billion years?
In plain words
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 statement
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.
What would settle it
Dust-to-gas and dust-to-metal ratios for a large sample at $z > 6$ with independent dust temperatures, compared with chemical evolution models.