APM z>4 QSO Survey: Distribution and Evolution of High Column Density HI Absorbers

Details APM z>4 QSO Survey: Distribution and Evolution of High Column Density HI Absorbers APM z>4 QSO Survey: Distribution and Evolution of High Column Density HI Absorbers

1996-08-22

arxiv.org/abs/astro-ph/9608146v1

Astronomy and Astrophysics

Astrophysics

To appear in MNRAS. Latex file (10 pages of text) plus 14 separate postscript figure files. Requires mn.sty. Postscript versio

Scientific paper

Eleven candidate damped Lya absorption systems were identified in 27 spectra of the quasars from the APM z>4 survey covering the redshift range 2.83.5). High resolution echelle spectra (0.8A FWHM) have been obtained for three quasars, including 2 of the highest redshift objects in the survey. Two damped systems have confirmed HI column densities of N(HI) >= 10^20.3 atoms cm^-2, with a third falling just below this threshold. We have discovered the highest redshift damped Lya absorber known at z=4.383 in QSO BR1202-0725. The APM QSOs provide a substantial increase in the redshift path available for damped surveys for z>3. We combine this high redshift sample with other quasar samples covering the redshift range 0.008 < z < 4.7 to study the redshift evolution and the column density distribution function for absorbers with log N(HI)>=17.2. In the HI column density distribution f(N)=kN^-beta we find evidence for breaks in the power law, flattening for 17.2< log N(HI)<21 and steepening for log N(HI)>21.2. The column density distribution function for the data with log N(HI)>=20.3 is better fit with the form f(N)=(f*/N*)(N/N*)^-beta exp(-N/N*). Significant redshift evolution in the number density per unit redshift is evident in the higher column density systems with an apparent decline in N(z) for z>3.5.

Affiliated with

Also associated with

No associations

Rating

APM z>4 QSO Survey: Distribution and Evolution of High Column Density HI Absorbers 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 APM z>4 QSO Survey: Distribution and Evolution of High Column Density HI Absorbers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and APM z>4 QSO Survey: Distribution and Evolution of High Column Density HI Absorbers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-162013