利用JWST在宇宙正午时期大质量尘埃遮蔽星系中基于Pa$\alpha$、Br$\alpha$和Br$\beta$的恒星形成与星云消光研究
Star Formation and Nebular Attenuation from Pa$α$, Br$α$, and Br$β$ in Massive Dust-obscured Galaxies at Cosmic Noon using JWST
- The University of Texas at Austin（德克萨斯大学奥斯汀分校）
- University of Maryland, College Park（马里兰大学帕克分校）
- University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校）
- Tufts University（塔夫茨大学）
- Space Telescope Science Institute（太空望远镜科学研究所）
- University of Arizona（亚利桑那大学）
- California Institute of Technology（加州理工学院）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究利用JWST近红外复合线测量宇宙正午大质量尘埃遮蔽星系的恒星形成率，量化星云消光，发现红外光度法高估SFR约2.5倍，揭示恒星形成历史可能下降或受AGN影响。
AI中文摘要：
近红外氢复合线可以提供可靠的恒星形成率，如果尘埃消光效应随波长增加而持续减弱的话。为了量化近红外消光并最终在宇宙恒星形成高峰期测量准确的恒星形成率（SFRs），我们展示了在$z\sim 1-2$的27个发光红外星系中Pa$\alpha$、Br$\alpha$和Br$\beta$的探测结果，这些星系包括纯恒星形成星系以及尘埃遮蔽的活动星系核（AGN）。利用JWST MIRI（中红外仪器）LRS（低分辨率光谱仪）和斯皮策太空望远镜IRS的联合光谱，我们通过一个由13个在Pa$\alpha$发射（$1.87\\, \mu$m）中探测到的星系、14个在Br$\alpha$（$4.05\\, \mu$m）中探测到的星系和12个在Br$\beta$（$2.63\\, \mu$m）中探测到的星系组成的子样本量化了我们样本的恒星形成率。通过结合单个星系中的多条近红外复合线，我们计算了星云消光，发现$A_\lambda\sim3$星等在$\sim2\\,\mu$m处，$A_\lambda\sim1$星等在$\sim4\\,\mu$m处。星云线追踪了约10百万年时间尺度上的恒星形成，我们将其与总红外光度（$L_{\rm IR}$）进行比较，后者探测了过去约100百万年内的恒星形成。使用常见转换从$L_{\rm IR}$测量的SFRs系统性地高于从消光校正的星云线测量推导出的SFRs，因子约为2.5。这可能表明恒星形成历史在下降或保持静态，并伴有过去的爆发，或者对$\rm SFR_{\rm IR}$存在系统效应，例如来自演化恒星群的尘埃加热和/或活动星系核的影响。
英文摘要：
Near-infrared hydrogen recombination lines can provide robust star-formation rates if the effects of dust attenuation continue to diminish towards longer wavelengths. To quantify near-infrared attenuation and ultimately measure accurate star-formation rates (SFRs) at the height of cosmic star-formation, we present Pa$α$, Br$α$, and Br$β$ detections in $27$ luminous infrared galaxies at $z\sim 1-2$, including pure star-forming galaxies as well as dust-obscure Active Galactic Nuclei (AGN). Using combined spectra from the JWST MIRI (Mid-Infrared Instrument) LRS (Low Resolution Spectrometer) and the Spitzer Space Telescope IRS we quantify the star formation rates of our sample using a sub-sample of 13 galaxies detected in Pa$α$ emission ($1.87\, μ$m), 14 galaxies detected in Br$α$ ($4.05\, μ$m), and 12 galaxies detected in Br$β$ ($2.63\, μ$m). By combining multiple near-infrared recombination lines in individual galaxies we calculate nebular attenuation, finding $A_λ\sim3$ mag at $\sim2\,μ$m and $A_λ\sim1$ mag at $\sim4\,μ$m. Nebular lines trace the SFR on $\sim 10$ Myr timescales, which we compare to the total infrared luminosity ($L_{\rm IR}$) which probes the star formation over the last $\sim 100$ Myr. SFRs measured from $L_{\rm IR}$ using common conversions are systematically higher than the SFRs derived from attenuation-corrected nebular line measurements by a factor of $\sim2.5$. This could be indicative of a declining or static star formation history with a past burst or systematic effects on $\rm SFR_{\rm IR}$ such as dust heating from evolved stellar populations, and/or an active galactic nucleus.
