The Proximity Effect, the UV Background and the Statistics of the Lyman-Alpha Lines at High Resolution
The Proximity Effect, the UV Background and the Statistics of the Lyman-Alpha Lines at High Resolution
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高分辨率莱曼-阿尔法线的邻近效应、紫外背景和统计
DOI：
10.1086/177492
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
S. Savaglio
中科院分区：
文献类型：
--
作者：
E. Giallongo;S. Cristiani;S. D’odorico;A. Fontana;S. Savaglio
我们介绍了ESO NTT望远镜拍摄的六个高红移qso的高分辨率（R \simeq 28000）光谱结果，这些光谱可以详细研究红移区间z=2.8-4.1的Ly-alpha种群。Ly-alpha谱线的典型多普勒参数位于b=20 \div 30 km/s区间，对应于温度T>24000K，其数量级为15的一小部分% in the range 10 =13.3) in the redshift interval z=1.7-4.1. A Maximum Likelihood analysis has been applied to estimate SIMULTANEOUSLY the best fit parameters of the Ly-alpha$ statistics AND of the UV background. After correcting for the blanketing of weak lines, we confirm that the column density distribution is best represented by a double power-law with a break at logN_{HI}\simeq14, with a slope beta_s=1.8 for higher column densities and a flatter slope beta_f=1.4 below the break. A value J_{LL}= 5 \pm1 \times10^{-22} erg/cm^2/s/Hz/sr is derived for the UV background in the redshift interval z=1.7-4.1, consistent with the predicted QSO contribution. No evidence is found for redshift evolution of the UVB in the same redshift interval. The comoving volume density distributions of protogalactic Damped and Lyman Lymit systems and Ly-alpha clouds with log N_{HI}>= 14 and radii R\simeq 200 kpc are found to be similar, suggesting a possible common association with galaxies.
We present results from high resolution (R\simeq 28000) spectra of six high- redshift QSOs taken at the ESO NTT telescope that allow the detailed study of the Ly-alpha population in the redshift interval z=2.8-4.1. The typical Doppler parameters found for the Ly-alpha lines lie in the interval b=20\div30 km/s, corresponding to temperatures T>24000K, with a fraction of the order 15% in the range 10 =13.3) in the redshift interval z=1.7-4.1. A Maximum Likelihood analysis has been applied to estimate SIMULTANEOUSLY the best fit parameters of the Ly-alpha$ statistics AND of the UV background. After correcting for the blanketing of weak lines, we confirm that the column density distribution is best represented by a double power-law with a break at logN_{HI}\simeq14, with a slope beta_s=1.8 for higher column densities and a flatter slope beta_f=1.4 below the break. A value J_{LL}= 5 \pm1 \times10^{-22} erg/cm^2/s/Hz/sr is derived for the UV background in the redshift interval z=1.7-4.1, consistent with the predicted QSO contribution. No evidence is found for redshift evolution of the UVB in the same redshift interval. The comoving volume density distributions of protogalactic Damped and Lyman Lymit systems and Ly-alpha clouds with log N_{HI}>= 14 and radii R\simeq 200 kpc are found to be similar, suggesting a possible common association with galaxies.