A large population of galaxies 9 to 12 billion years back in the history of the Universe
A large population of galaxies 9 to 12 billion years back in the history of the Universe
复制标题
宇宙历史上 9 至 120 亿年前的大量星系
作者：
O. Fèvre;S. Paltani;S. Arnouts;S. Charlot;S. Foucaud;O. Ilbert;O. Ilbert;H. McCracken;G. Zamorani;D. Bottini;B. Garilli;V. Brun;D. Maccagni;J. Picat;R. Scaramella;M. Scodeggio;L. Tresse;G. Vettolani;A. Zanichelli;C. Adami;S. Bardelli;M. Bolzonella;A. Cappi;P. Ciliegi;T. Contini;P. Franzetti;I. Gavignaud;L. Guzzo;A. Iovino;B. Marano;C. Marinoni;A. Mazure;B. Meneux;R. Merighi;R. Pelló;A. Pollo;L. Pozzetti;M. Radovich;E. Zucca;M. Arnaboldi;M. Bondi;A. Bongiorno;G. Busarello;L. Gregorini;F. Lamareille;G. Mathez;Y. Mellier;P. Merluzzi;V. Ripepi;D. Rizzo
为了了解星系的演化，我们需要尽可能准确地知道在不同的时期宇宙中存在着多少星系。到目前为止，年轻宇宙中的星系主要是通过它们预期的光学颜色来识别的，但这留下了一种可能性，即大量星系群体仍然没有被发现，因为它们的颜色是恒星、气体、尘埃或活动星系核的复杂混合的结果。在这里，我们报告了一项流量受限的I波段星系调查的结果，回顾时间为90亿到120亿年。我们发现了970个光谱红移在1.4到5之间的星系。这一群体比之前估计的大1.6到6.2倍，而且差异朝着更亮的星等增加。强烈的紫外线连续体(在星系的其余部分)表明，恒星的形成速度每年超过10-100个太阳质量。因此，代表恒星体积平均产量的宇宙恒星形成率比以前在红移3到4的时候测得的要高。
To understand the evolution of galaxies, we need to know as accurately as possible how many galaxies were present in the Universe at different epochs. Galaxies in the young Universe have hitherto mainly been identified using their expected optical colours, but this leaves open the possibility that a significant population remains undetected because their colours are the result of a complex mix of stars, gas, dust or active galactic nuclei. Here we report the results of a flux-limited I-band survey of galaxies at look-back times of 9 to 12 billion years. We find 970 galaxies with spectroscopic redshifts between 1.4 and 5. This population is 1.6 to 6.2 times larger than previous estimates, with the difference increasing towards brighter magnitudes. Strong ultraviolet continua (in the rest frame of the galaxies) indicate vigorous star formation rates of more than 10–100 solar masses per year. As a consequence, the cosmic star formation rate representing the volume-averaged production of stars is higher than previously measured at redshifts of 3 to 4.