I thought that z= 7.5 was the maximum for galaxies to form after re ionization but this paper puts it at z=8.38, can galaxies have formed this early? arXiv:1703.02039 [pdf, other] Dust in the reionization era: ALMA observations of a z=8.38 Galaxy Nicolas Laporte, Richard S. Ellis, Frederic Boone, Franz E. Bauer, David Quénard, Guido W. Roberts-Borsani, Roser Pelló, Ismael Pérez-Fournon, Alina Streblyanska Comments: Accepted for publication in ApJL Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO) We report on the detailed analysis of a gravitationally-lensed Y-band dropout, A2744_YD4, selected from deep Hubble Space Telescope imaging in the Frontier Field cluster Abell 2744. Band 7 observations with the Atacama Large Millimeter Array (ALMA) indicate the proximate detection of a significant 1mm continuum flux suggesting the presence of dust for a star-forming galaxy with a photometric redshift of z≃8. Deep X-SHOOTER spectra confirms the high redshift identity of A2744_YD4 via the detection of Lyman α emission at a redshift z=8.38. The association with the ALMA detection is confirmed by the presence of [OIII] 88μm emission at the same redshift. Although both emission features are only significant at the 4 σ level, we argue their joint detection and the positional coincidence with a high redshift dropout in the HST images confirms the physical association. Analysis of the available photometric data and the modest gravitational magnification (μ≃2) indicates A2744_YD4 has a stellar mass of ∼ 2×109 M⊙, a star formation rate of ∼20 M⊙/yr and a dust mass of ∼6×106 M⊙. We discuss the implications of the formation of such a dust mass only ≃200 Myr after the onset of cosmic reionisation.