arXiv 1209.34732012-09-16astro-ph.COastro-ph.IM

UV连续谱作为星系恒星形成率指示器的精度

The accuracy of the UV continuum as an indicator of the star formation rate in galaxies

Stephen M. Wilkins, Violeta Gonzalez-Perez, Cedric G. Lacey, Carlton M. Baugh

备注：: 7 pages, 9 figures, accepted in MNRAS
DOI：: 10.1111/j.1365-2966.2012.22092.x

摘要：

静止坐标系内禀紫外光度常被用作星系瞬时恒星形成率（SFR）的指标。虽然它在一般是一个强大的指标，正在进行的恒星形成活动，校准的紫外线光度SFR（$B_ν$）的精确值，是敏感的各种物理性质，如最近的恒星形成和金属富集的历史，随着恒星初始质量函数的选择。这些属性的恒星形成星系人口的分布，然后表明，通过一个单一的校准是不合适的，除非适当的资格与校准的不确定性。我们调查的援助下，{ \sc galform}半解析模型的星系形成，UV-SFR校准的分布获得了真实的恒星形成和金属富集的历史。在$z=0$中，我们发现当初始质量函数固定（到Kennicutt IMF）时，中值校准是$B_{\rm fuv}=0.9$，其中${\rm SFR}/[{\rm M_{\odot}\,yr^{-1}}]=B_ν\times 10^{-28}\times L_ν/[{\rm ergs\,s^{-1}\,Hz^{-1}}]$。然而，分布$B_{\rm fuv}$的宽度表明，对于一个单一的对象有大约20%的{ \em内在}的不确定性（在$z=0$，上升到$\simeq 30%$在$z=6$）的恒星形成率推断FUV光度没有额外的限制，恒星形成的历史或金属丰度。我们还发现，校准$B_{\rm fuv}$的中值与恒星形成率和红移（在$z>3$）提高的影响，从紫外线的恒星形成率的正确测定。

英文摘要：

The rest-frame intrinsic UV luminosity is often used as an indicator of the instantaneous star formation rate (SFR) in a galaxy. While it is in general a robust indicator of the ongoing star formation activity, the precise value of the calibration relating the UV luminosity to the SFR ($B_ν$), is sensitive to various physical properties, such as the recent star formation and metal enrichment histories, along with the choice of stellar initial mass function. The distribution of these properties for the star-forming galaxy population then suggests that the adoption of a single calibration is not appropriate unless properly qualified with the uncertainties on the calibration. We investigate, with the aid of the {\sc galform} semi-analytic model of galaxy formation, the distribution of UV-SFR calibrations obtained using realistic star formation and metal enrichment histories. At $z=0$, we find that when the initial mass function is fixed (to the Kennicutt IMF), the median calibration is $B_{\rm fuv}=0.9$ where ${\rm SFR}/[{\rm M_{\odot}\,yr^{-1}}]=B_ν\times 10^{-28}\times L_ν/[{\rm ergs\,s^{-1}\,Hz^{-1}}]$. However, the width of the distribution $B_{\rm fuv}$ suggests that for a single object there is around a 20% {\em intrinsic} uncertainty (at $z=0$, rising to $\simeq 30%$ at $z=6$) on the star formation rate inferred from the FUV luminosity without additional constraints on the star formation history or metallicity. We also find that the median value of the calibration $B_{\rm fuv}$ is correlated with the star formation rate and redshift (at $z>3$) raising implications for the correct determination of the star formation rate from the UV.

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