The Origin of Dust in High-Redshift Quasars: The Case of J1148+5251.

Two distinct scenarios have been proposed to explain the origin of dust observed in the high-redshift (z = 6.4) quasar J1148+5251. The first scenario suggests that because of the relatively young age of the universe (∼890 Myr), only massive stars could have produced the large amount of dust observed in this object. The second scenario assumes a significantly older galactic age, so that most of the dust could have formed in lower-mass AGB stars that would have sufficient time to evolve off the main sequence. In this contribution we offer a critical analysis of both scenarios, and briefly discuss alternative suggestions for the origin of dust in this object. [ABSTRACT FROM AUTHOR]