@article{oai:soar-ir.repo.nii.ac.jp:00015849,
 author = {Misawa,  T and Tytler,  D and Iye,  M and Paschos,  P and Norman,  M and Kirkman,  D and O'Meara,  J and Suzuki,  N and Kashikawa,  N},
 issue = {6},
 journal = {ASTRONOMICAL JOURNAL},
 month = {Dec},
 note = {Using H I absorption alone, we attempt to separate H I absorption lines in quasar spectra into two categories: higher density lines (HDLs) and lower density lines (LDLs), and we discuss the difference in their physical properties. We deblend and fit all H I lines with Voigt profiles and make an unbiased sample of H I lines covering a wide column density range (12<log N-H I [cm(-2)]<19). To reduce the influence of line blending, we simultaneously fit several Lyman series lines. As a result of a two-point correlation analysis, we found that higher column density H I lines are clustering at Deltav<200 km s(-1), whereas lower ones cluster at &UDelta;v<100 km s(-1). We define HDLs as H I lines with 15<log N-H I<19 and all H I lines within 200 km s(-1) of a line with log N-H I>15 and LDLs as all others with 12<log N-H I<15. We found that the HDLs have smaller minimum b-values for a given column density than the LDLs. This difference is successfully reproduced by our hydrodynamic simulation. The LDLs seem to be cool or shock-heated diffuse intergalactic medium gas, whereas the HDLs are likely to be cooler dense gas near to galaxies., Article, ASTRONOMICAL JOURNAL. 128(6):2954-2961 (2004)},
 pages = {2954--2961},
 title = {HI gas in higher density regions of the intergalactic medium},
 volume = {128},
 year = {2004}
}