Chary 2007 Spitzer对3个高红移伽玛暴宿主星系的观测

主要内容:
三个z～5的宿主星系的观测，表明这三个星系的光度比那里的平均光度要低三倍，说明在GOODS的深度巡天中并没有包括所有的恒星形成中的星系。这对恒星形成率的估计很有帮助。

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文章信息:
Spitzer Observations of Gamma-Ray Burst Host Galaxies: A Unique Window into High Redshift Chemical Evolution and Star-formation

Authors: Ranga-Ram Chary, Edo Berger, Len Cowie

(Submitted on 17 Aug 2007)

Abstract: We present deep Spitzer 3.6 micron observations of three z~5 GRB host galaxies. Our observations reveal that z~5 GRB hosts are a factor of 3 less luminous than the median rest-frame V-band luminosity of spectroscopically confirmed z~5 galaxies in the GOODS fields and the UDF. The strong connection between GRBs and massive star formation implies that not all star-forming galaxies at these redshifts are currently being accounted for in deep surveys and GRBs provide a unique way to measure the contribution to the star-formation rate density from galaxies at the faint end of the galaxy luminosity function. By correlating the co-moving star-formation rate density with co-moving GRB rates at lower redshifts, we estimate a lower limit to the star-formation rate density of 0.12+/-0.09 and 0.09+/-0.05 M_sun/yr/Mpc^3 at z~4.5 and z~6, respectively. Finally, we provide evidence that the average metallicity of star-forming galaxies evolves as (stellar mass density)^(0.69+/-0.17) between $z\sim5$ and $z\sim0$, probably indicative of the loss of a significant fraction of metals to the intergalactic medium, particularly in low-mass galaxies.

arXiv:0708.2440 [ps, pdf, other]