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arXiv 2101.05342astro-ph.GA
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高亮度致密蓝星系的亮度函数到z=1的演化

The Evolution of the Luminosity Function for Luminous Compact Blue Galaxies to z=1

L. R. Hunt, D. J. Pisano, S. M. Crawford, M. A. Bershady, G. D. Wirth

摘要:

明亮的致密蓝星系(LCBG)是一种致密的恒星形成星系,在本星系中很少被观测到,但在z=1处却很丰富。在宇宙回望时间内,LCBG数密度的增加大致遵循了同一时期宇宙恒星形成率密度的增加。我们使用公开可用的数据在COSMOS领域研究的最大的均匀样本的LCBG的演变,迄今为止,推导出他们的光度函数在四个红移箱的范围$0.1\leq~z\leq1$。我们发现,在这个红移范围内,特征光度(M $^{*}$)增加了$\sim$ 0.2等,数密度增加了四倍。虽然LCBG只占$18\%$的星系比$z\sim0.2$的M $_{B}=-$ 18.5更亮,但它们大致构成$54\%$的z $\sim$ 0.9。数量密度的强烈演化表明,LCBG是一个重要的星系群,以更好地了解自$z\sim1$以来宇宙恒星形成率密度的下降。

英文摘要:

Luminous Compact Blue Galaxies (LCBGs) are compact, star-forming galaxies that are rarely observed in the local universe but abundant at z=1. This increase in LCBG number density over cosmic lookback time roughly follows the increase in the star formation rate density of the universe over the same period. We use publicly available data in the COSMOS field to study the evolution of the largest homogeneous sample of LCBGs to date by deriving their luminosity function in four redshift bins over the range $0.1\leq~z\leq1$. We find that over this redshift range, the characteristic luminosity (M$^{*}$) increases by $\sim$0.2 mag, and the number density increases by a factor of four. While LCBGs make up only about $18\%$ of galaxies more luminous than M$_{B}=-$18.5 at $z\sim0.2$, they constitute roughly $54\%$ at z$\sim$0.9. The strong evolution in number density indicates that LCBGs are an important population of galaxies to study in order to better understand the decrease in the star formation rate density of the universe since $z\sim1$.

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