We use a sample of star-forming field and protocluster galaxies at z=2.0–2.5 with Keck/MOSFIRE K-band spectra, a wealth of rest-frame ultraviolet (UV) photometry, and Spitzer/MIPS and Herschel/PACS observations, to dissect the relation between the ratio of infrared (IR) to UV luminosity (IRX) versus UV slope (β) as a function of gas-phase metallicity (∼8.2–8.7). We find no significant dependence of the IRX-β trend on environment. However, we find that at a given β, IRX is highly correlated with metallicity, and less correlated with mass, age, and specific star formation rate (sSFR). We conclude that, of the physical properties tested here, metallicity is the primary physical cause of the IRX-β scatter, and the IRX correlation with mass is presumably due to the mass dependence on metallicity. Our results indicate that the UV attenuation curve steepens with decreasing metallicity, and spans the full range of slope possibilities from a shallow Calzetti-type curve for galaxies with the highest metallicity in our sample (∼8.6) to a steep Small Magellanic Cloud (SMC)-like curve for those with ∼8.3. Using a Calzetti (SMC) curve for the low (high) metallicity galaxies can lead to up to a factor of 3 overestimation (underestimation) of the UV attenuation and obscured star formation rate. We speculate that this change is due to different properties of dust grains present in the interstellar medium of low- and high-metallicity galaxies.

我们使用z = 2.0–2.5的恒星形成场和原星系团样本，以及Keck/MOSFIRE K波段光谱、大量的静止帧紫外 (UV) 光度测量以及 Spitzer/MIPS 和 Herschel/PACS 观测，以剖析红外 (IR) 与紫外光度 (IRX) 之比与紫外斜率 ( β ) 作为气相金属丰度 (~ 8.2–8.7)的函数之间的关系。我们发现 IRX- β趋势对环境没有显着依赖性。然而，我们发现在给定的β 下，IRX 与金属丰度高度相关，而与质量、年龄和特定恒星形成率 (sSFR) 的相关性较小。我们得出的结论是，在这里测试的物理特性中，金属丰度是 IRX-的主要物理原因β散射以及 IRX 与质量的相关性可能是由于质量对金属丰度的依赖性。我们的结果表明，UV 衰减曲线随着金属丰度的降低而变陡，并跨越从我们样本中金属丰度最高的星系（~ 8.6）的浅 Calzetti 型曲线到陡峭的小麦哲伦星云（SMC）的全部斜率可能性～8.3 的曲线。对低（高）金属丰度星系使用 Calzetti (SMC) 曲线可能导致紫外线衰减和恒星形成率被高估（低估）3 倍。我们推测这种变化是由于低金属度和高金属度星系的星际介质中存在的尘埃颗粒的不同特性造成的。