First Comparison of Ionization and Metallicity in Two Lines of Sight Toward HE 1104-1805 AB at z=1.66

Details First Comparison of Ionization and Metallicity in Two Lines of Sight Toward HE 1104-1805 AB at z=1.66 First Comparison of Ionization and Metallicity in Two Lines of Sight Toward HE 1104-1805 AB at z=1.66

1998-06-10

arxiv.org/abs/astro-ph/9806143v2

Astronomy and Astrophysics

Astrophysics

LaTeX, 49 pages including 10 figures, minor changes introduced. Now in press at ApJ (1999 March 10 issue)

Scientific paper

10.1086/306879

Using new HST/FOS, NTT/EMMI, and Keck/HIRES spectra of the gravitationally-lensed double QSO HE 1104-1805 AB (z=2.31, \theta=3.2), and assuming UV photoionization by a metagalactic radiation field, we derive physical conditions (ionization levels, metal abundances and cloud sizes along the lines of sight) in five CIV+MgII absorption systems clustered around z=1.66 along the two lines of sight. Three of these systems are associated with a damped Ly-alpha (DLA) system with logN(HI)=20.85, which is observed in A. The other two systems are associated with a Lyman-limit system with logN(HI)=17.57 (B). The CIV and MgII line profiles in A resemble those in the B spectra, and span \Delta v=360 km/s. Assuming that the relative metal abundances in these absorption systems are the same as observed in the DLA system, we find that the observed N(CIV)/N(MgII) ratios imply ionization parameters of log\Gamma=-2.95 to -2.35. Consequently, these clouds should be small (0.5-1.6 kpc with a hydrogen density n_H<=0.01 cm-3) and relatively highly ionized. The absorption systems to B are found to have a metallicity 0.63 times lower than the metallicity of the gas giving rise to the DLA system, Z(DLA)= 0.1*Z(solar). We detect OVI at z=1.66253 in both QSO spectra, but no associated NV. Our model calculations lead us to conclude that the CIV clouds should be surrounded by large (>= 100 kpc) highly ionized low-density clouds (n_H\sim e-4 cm-3), in which OVI, but only weak CIV absorption occurs. In this state, log\Gamma>=-1.2 reproduces the observed ratio of N(OVI)/N(NV)>60. These results are discussed in view of the disk/halo and hierarchical structure formation models.

Affiliated with

Also associated with

No associations

Rating

First Comparison of Ionization and Metallicity in Two Lines of Sight Toward HE 1104-1805 AB at z=1.66 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with First Comparison of Ionization and Metallicity in Two Lines of Sight Toward HE 1104-1805 AB at z=1.66, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and First Comparison of Ionization and Metallicity in Two Lines of Sight Toward HE 1104-1805 AB at z=1.66 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-611458