论文标题
HEII Lyman Alpha和Beta传输尖峰的Z> 3.5的HEII电源扩展的新证据
New Evidence for Extended HeII Reionization at z>3.5 from HeII Lyman Alpha and Beta Transmission Spikes
论文作者
论文摘要
We present new high-resolution (R~14,000) spectra of the two brightest HeII-transparent quasars in the far-UV (FUV) at z>3.5, HE2QSJ2311-1417 (z=3.70) and HE2QSJ1630+0435 (z=3.81), obtained with the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST).在主要饱和的HEII吸收光谱中，两种视线均显示出几个孤立的分辨率（最大FWHM> 50 km/s的全宽度）在HEII ly $α$和heii ly $β$中的传输峰值。此类尖峰的发生率随着红移的增加而降低，但两种视线在z> 3.5处显示出明显的尖峰，这表明在z> 3.5层间培养基（IgM）中存在完全离子的区域。我们采用一种自动算法来比较检测到的HEII传输尖峰的数量与从立方（100/h CMPC）的输出创建的模拟光谱的预测数（100/h CMPC）^3光学上的NYX流体动力学模拟，假设有一系列UV背景光合率$γ_\ Mathrm {Heii} $ {Heii} $。从Ly $α$和ly $β$传输尖峰的发生率中，我们推断出类似的光电离速率为$γ_\ Mathrm {heii} = 2.0^{+0.6} _ { - 0.5} \ times 10^{ - 15} $ s $ s $ s $ s $^{ - 1} $ $γ_\ mathrm {heii} = 0.9 \ pm0.3 \ times 10^{ - 15} $ s $ s $^{ - 1} $ at 3.460 <z <3.685。由于传输尖峰表明沿两条视线的Z> 3.5处完全离子化区域，因此我们的观察结果提供了进一步的证据，表明HEII电离在这些红移下取得了显着进展。
We present new high-resolution (R~14,000) spectra of the two brightest HeII-transparent quasars in the far-UV (FUV) at z>3.5, HE2QSJ2311-1417 (z=3.70) and HE2QSJ1630+0435 (z=3.81), obtained with the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). In the predominantly saturated HeII absorption spectra, both sightlines show several isolated resolved (full width at half maximum FWHM>50 km/s) transmission spikes in HeII Ly$α$ and HeII Ly$β$. The incidence of such spikes decreases with increasing redshift, but both sightlines show significant spikes at z>3.5, signaling the presence of fully ionized regions in the z>3.5 intergalactic medium (IGM). We employ an automated algorithm to compare the number of detected HeII transmission spikes to predictions from mock spectra created from the outputs of a cubic (100/h cMpc)^3 optically thin Nyx hydrodynamical simulation, assuming a range of UV background photoionization rates $Γ_\mathrm{HeII}$. From the incidence of Ly$α$ and Ly$β$ transmission spikes we infer similar photoionization rates of $Γ_\mathrm{HeII}=2.0^{+0.6}_{-0.5}\times 10^{-15}$s$^{-1}$ at 3.51<z<3.66 and $Γ_\mathrm{HeII}=0.9\pm0.3 \times 10^{-15}$s$^{-1}$ at 3.460<z<3.685, respectively. Because the transmission spikes indicate fully ionized regions at z>3.5 along both lines of sight, our observations provide further evidence that HeII reionization had substantially progressed at these redshifts.
