Damped lyman alpha systems at z<1.65: the expanded sdss hst sample
Damped lyman alpha systems at z<1.65: the expanded sdss hst sample
复制标题
DOI：
10.1086/498132
复制
发表时间：
2005-09
期刊：
影响因子：
--
通讯作者：
S. Rao;D. Turnshek;Daniel. B. Nestor U. Pittsburgh;U. Florida
中科院分区：
文献类型：
--
作者：
S. Rao;D. Turnshek;Daniel. B. Nestor U. Pittsburgh;U. Florida
我们给出了我们的HST Cycle 11对低红移(z0.1A)的测量结果。(2)具有0.3A W2796~2的MgII系统的平均N(HI)。(4)在0.5<；z<；5.0的不确定范围内，Omega_(Dla)是不变的。(5)N(HI)分布的斜率随红移变化不大。然而，由于我们的样品中较高比例的高N(HI)体系，低红移分布稍微平坦一些。(6)利用MGII测量统计的精度，我们发现可能存在欧米茄{DLA}从z=0.5下降到z=0的证据。我们重申Hopkins，Rao和Turnshk的结论，DLA调查可能遗漏了很高的中性气柱，因为它们的截面很小，因此Omega_{DLA}可能不包括宇宙中的大部分中性气体质量。(节选)
We present results of our HST Cycle 11 Survey for low-redshift (z 0.1 A. (2) The mean N(HI) of MgII systems with 0.3 A \le W2796 ~ 2. (4) Omega_{DLA} is constant for 0.5<z<5.0 to within the uncertainties. This is larger than Omega_{gas}(z=0) by a factor of ~2. (5) The slope of the N(HI) distribution does not change significantly with redshift. However, the low redshift distribution is marginally flatter due to the higher fraction of high N(HI) systems in our sample. (6) Finally, using the precision of MgII survey statistics, we find that there may be evidence of a decreasing Omega_{DLA} from z=0.5 to z=0. We reiterate the conclusion of Hopkins, Rao, & Turnshek that very high columns of neutral gas might be missed by DLA surveys because of their very small cross sections, and therefore, that Omega_{DLA} might not include the bulk of the neutral gas mass in the Universe. (Abridged)