The Evolution of Dust in the Early Universe with Applications to the Galaxy SDSS J1148+5251

Abstract

Dusty hyperluminous galaxies in the early universe provide unique environments for studying the role of massive stars in the formation and destruction of dust. At redshifts above ~6, when the universe was less than ~1 Gyr old, dust could have only condensed in the explosive ejecta of Type II supernovae (SNe), since most of the progenitors of the asymptotic giant branch stars, the major alternative source of interstellar dust, did not have time to evolve off the main sequence since the onset of star formation. In this paper we present analytical models for the evolution of the gas, dust, and metals in high-redshift galaxies, with a special application to SDSS J1148+5251 (hereafter J1148+5251), a hyperluminous quasar at z = 6.4. We find that an average SN must condense at least 1 M☉ of dust to account for the observed dust mass in J1148+5251. Observationally, it is in excess of the largest dust yield of 0.02 M☉ found thus far in the ejecta of any SN. If future observations find this to be a typical SN dust yield, then additional processes, such as accretion onto preexisting grains or condensation around the active galactic nucleus, will need to be invoked to account for the large amount of dust in this and similar objects. The galaxy's star formation history is still uncertain, and current observations of the gas, metal, and dust contents of J1148+5251 can be reproduced by either an intensive and short burst of star formation (ψ 103 M☉ yr-1) with a duration of 108 yr or a much lower star formation rate (ψ ≈ 100 M☉ yr-1) occurring over the lifetime of the galaxy.