Salvaterra R, Valle M Della, Campana S, Chincarini G, Covino S, D'Avanzo P, Fernández-Soto A, Guidorzi C, Mannucci F, Margutti R, Thöne C C, Antonelli L A, Barthelmy S D, De Pasquale M, D'Elia V, Fiore F, Fugazza D, Hunt L K, Maiorano E, Marinoni S, Marshall F E, Molinari E, Nousek J, Pian E, Racusin J L, Stella L, Amati L, Andreuzzi G, Cusumano G, Fenimore E E, Ferrero P, Giommi P, Guetta D, Holland S T, Hurley K, Israel G L, Mao J, Markwardt C B, Masetti N, Pagani C, Palazzi E, Palmer D M, Piranomonte S, Tagliaferri G, Testa V
INAF, Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy.
Nature. 2009 Oct 29;461(7268):1258-60. doi: 10.1038/nature08445.
Gamma-ray bursts (GRBs) are produced by rare types of massive stellar explosion. Their rapidly fading afterglows are often bright enough at optical wavelengths that they are detectable at cosmological distances. Hitherto, the highest known redshift for a GRB was z = 6.7 (ref. 1), for GRB 080913, and for a galaxy was z = 6.96 (ref. 2). Here we report observations of GRB 090423 and the near-infrared spectroscopic measurement of its redshift, z = 8.1(-0.3)(+0.1). This burst happened when the Universe was only about 4 per cent of its current age. Its properties are similar to those of GRBs observed at low/intermediate redshifts, suggesting that the mechanisms and progenitors that gave rise to this burst about 600,000,000 years after the Big Bang are not markedly different from those producing GRBs about 10,000,000,000 years later.
伽马射线暴（GRBs）由罕见类型的大质量恒星爆炸产生。它们迅速衰减的余辉在光学波长下通常足够明亮，以至于在宇宙学距离上也能被探测到。迄今为止，已知GRB的最高红移为z = 6.7（参考文献1，针对GRB 080913），而星系的最高红移为z = 6.96（参考文献2）。在此，我们报告对GRB 090423的观测及其红移的近红外光谱测量结果，z = 8.1（-0.3）（+0.1）。这次爆发发生时，宇宙年龄仅约为其当前年龄的4%。其性质与在低/中等红移处观测到的GRB相似，这表明在大爆炸后约6亿年产生此次爆发的机制和前身与约100亿年后产生GRB的机制和前身并无显著差异。
