2006A&A...458..427J


Query : 2006A&A...458..427J

2006A&A...458..427J - Astronomy and Astrophysics, volume 458, 427-439 (2006/11-1)

The evolution of Lyman α absorbers in the redshift range 0.5<z<1.9.

JANKNECHT E., REIMERS D., LOPEZ S. and TYTLER D.

Abstract (from CDS):

We investigate the evolution and the statistical properties of the Lyα absorbers of the intergalactic medium (IGM) in the largely unexplored redshift range z=0.5-1.9. We use high-resolution (R≥30000) UV (STIS) and optical (VLT/UVES and Keck/HIRES) spectra of nine bright quasars with zem<1.94. The Lyα lines detected in the lines of sight (LOS) towards these quasars are evaluated with a software package which determines simultaneously the quasar continuum and the line profiles. The main results for the combined Lyα line sample are summarized as follows: (o) The evolution of the number density of the absorbers can be described by the power law (dn)/(dz)∝(1+z)γ. The number density of the low column density lines (NHI=(1012.90-1014.00)cm–2) decreases with decreasing z with γ=0.74±0.31 in the interval z=0.7-1.9. A comparison with results at higher redshifts shows that it is decelerated in the explored redshift range and turns into a flat evolution for z->0. The stronger absorbers (NHI>1013.64cm–2) thin out faster (γ=1.50±0.45). The break in their evolution predicted for z=1.5-1.7 cannot be seen down to z=0.7. On the other hand, a comparison with values from the literature for the local number density gives a hint that this break occurs at lower redshift. (o) The distribution of the column densities of the absorbers is complete down to NHI=1012.90cm–2. It can be approximated by a single power law with the exponent β=1.60±0.03 over almost three orders of magnitude. β is redshift independent. (o) The Lyα lines with lower column densities as well as the higher column density lines show marginal clustering with a 2σ significance over short distances (Δv<200km/s and Δv<100km/s, respectively). We do not see any difference in the clustering with either column density or redshift. (o) The distribution of the Doppler parameters has a mean value of <b≥(34±22)km/s. This value is typical for the analyzed region. It does not change significantly with z.

Abstract Copyright:

Journal keyword(s): cosmology: observations - intergalactic medium

VizieR on-line data: <Available at CDS (J/A+A/458/427): table1.dat linelist.dat>

Nomenclature: List: [JRL2006] QSO J1634+7031 abs N.NNNNNNN N=1325.

Simbad objects: 9

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Number of rows : 9
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 QSO B0117+2118 QSO 01 20 17.2642359528 +21 33 46.197696168     16.1     ~ 123 0
2 QSO J0143-3917 QSO 01 43 33.6332389872 -39 17 00.066827076     16.28     ~ 26 0
3 4C -04.06 QSO 02 35 07.3418452008 -04 02 05.317096956   16.61 16.46 16.2   ~ 197 1
4 HE 0429-4901 ? 04 30.4 -48 55           ~ 4 0
5 HE 0515-4414 QSO 05 17 07.6238702856 -44 10 55.579731312 14.74 15.49 15.16     ~ 107 0
6 QSO B0747+4259 QSO 07 50 54.6474995592 +42 52 19.233881796   16.43 16.23     ~ 49 0
7 QSO B1630+3744 QSO 16 32 01.1117931960 +37 37 49.980505332   16.50 16.30     ~ 169 0
8 QSO B1634+7037 QSO 16 34 28.9917184368 +70 31 32.393436960   14.90 14.66     ~ 263 0
9 QSO J2227-2243 QSO 22 27 56.9352929832 -22 43 02.601281856     17.60     ~ 18 0

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2022.05.26-11:30:48

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