发表机构
Institute for Astronomy, University of Edinburgh; Astrophysics, Department of Physics, University of Oxford（爱丁堡大学天体物理研究所; 牛津大学物理系天体物理学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究依托JWST的JELS巡天，通过窄带测定z~6.1再电离时代的Hα光度函数，得到恒星形成率密度并探讨其金属丰度依赖性，凸显窄带巡天对探测暗弱Hα天体的重要性。
AI 中文摘要
星系中的近期恒星形成活动可通过Hα发射线实现最优追踪，特定红移下的Hα光度函数（LF）是探测宇宙恒星形成的可靠探针。我们利用詹姆斯·韦伯空间望远镜发射线巡天（JELS）筛选出的39个Hα发射体，首次通过窄带测定得到了再电离时代（EoR）z~6.1处的Hα光度函数。观测得到的和尘埃校正后的光度函数与近期无狭缝光谱测量结果大致相符，但与宇宙学模拟的预测存在显著差异，这可能反映了发射线与尘埃建模的差异。结合多个光度函数数据集的拟合有助于约束高红移处Hα光度函数的暗端斜率（-1.79<α_Hα<-1.62），但它随红移的演化仍存在不确定性。对JELS尘埃校正后的Hα光度函数进行积分，得到恒星形成率密度：假设连续谱与线消光比η_dust=A_cont(6563Å)/A_Hα=1时，log₁₀(ρ_SFR_Hα / (M☉ yr⁻¹ Mpc⁻³))=-1.93⁺⁰.¹⁴₋₀.₁₂；当η_dust=0.44时，该值为-2.00⁺⁰.¹⁶₋₀.₁₀。尽管尘埃校正存在不确定性，两种测量结果在误差范围内与此前采用光度函数积分极限（L_Hα,lim）和恒星形成率校准常数κ_Hα标准假设的结果一致。我们探究了κ_Hα的金属丰度依赖性，发现ρ_SFR_Hα相较于基准结果降低了0.43 dex，且不再与z~6处通过紫外测定的ρ_SFR一致。本研究凸显了窄带巡天在探测暗弱Hα天体、为再电离时代宇宙恒星形成活动提供新约束方面的重要性。
英文摘要
The recent star-formation activity in galaxies can be optimally traced by the H$α$ emission line, with the resulting H$α$ luminosity function (LF) at a given epoch providing a reliable probe of cosmic star formation. We present the first narrow-band determined H$α$ LF into the Epoch of Reionization (EoR) at $z\sim6.1$, using 39 H$α$ emitters selected from the JWST Emission Line Survey (JELS). The observed and dust-corrected LFs are broadly consistent with recent slitless spectroscopic measurements but show notable discrepancies with predictions from cosmological simulations, likely reflecting differences in emission-line and dust modelling. Fits combining multiple LF datasets help constrain the high-redshift faint-end slope of the H$α$ LF ($-1.79<α_{\rm{Hα}}<-1.62$), but there remains uncertainty in its evolution with redshift. Integrating the JELS dust-corrected H$α$ LFs yields a star-formation rate density of $\log_{10}(ρ_{\rm{SFR_{Hα}}}\,/\,\rm{M_{\odot}\,yr^{-1}\,Mpc^{-3}})=-1.93\,^{+0.14}_{-0.12}$ or $-2.00\,^{+0.16}_{-0.10}$, assuming a continuum-to-line extinction ratios $η_{\rm{dust}}=A_{\rm{cont}}(\rm{6563\,\mathring{A}})/A_{\rm{Hα}}=1$ and 0.44, respectively. Both measurements are consistent within uncertainties with previous results using standard assumptions for the LF integration limit ($L_{\rm{Hα,\,lim}}$) and SFR calibration constant $κ_{\rm{Hα}}$, despite the uncertainties in the dust corrections. We explore the metallicity dependence of $κ_{\rm{Hα}}$ and find $ρ_{\rm{SFR_{Hα}}}$ decreases 0.43 dex compared to the fiducial result and is no longer consistent with UV-determined $ρ_{\rm{SFR}}$ at $z\sim6$. This work highlights the importance of narrow-band surveys in probing the faint H$α$ population and providing new constraints on cosmic star-formation activity into the EoR.
Comments21 pages, 8 figures, submitted to the Monthly Notices of the Royal Astronomical Society (MNRAS)
