Neutral gas density in Damped Lyman Alpha systems
| dc.creator | Trenti, M. | |
| dc.creator | Stiavelli, M. | |
| dc.date | 2006-06-28 | |
| dc.date.accessioned | 2026-07-07T10:39:26Z | |
| dc.date.available | 2026-07-07T10:39:26Z | |
| dc.description | We estimate the intrinsic neutral gas density in Damped Lyman Alpha systems ($Ω_{HI}^{(DLA)}$) in the redshift range $ 2.2 \lesssim z \lesssim 5$ from the DLA SDSS DR_3 sample of optically selected quasars. We take into account self-consistently the obscuration on background quasars due to the dust present in Damped Lyman Alpha systems. We model the column density and redshift distribution of these systems by using both a non-parametric and a parametric approach. Under conservative assumptions on the dust content of Damped Lyman $α$ systems, we show that selection effects lead to underestimating the intrinsic neutral gas density by at least $15\%$ with respect to the observed neutral gas density. Over the redshift range $[2.2;5.5]$ we find $Ω_{HI}^{(DLA)}=0.97^{+0.08+0.28}_{-0.06-0.15} \cdot 10^{-3}$, where the first set of error bars gives the $1σ$ random errors and the second set gives the modeling uncertainty dependent on the fraction of metals in dust - from 0\% to 50\%. This value compares with $Ω_{HI}^{(DLA)}=0.82^{+0.05}_{-0.05}$ ($1σ$ error bars), which is obtained when no correction for dust is introduced. In the model with half of the metals mass in dust we cannot constraint $Ω_{HI}^{(DLA)}$ at a confidence level higher than $90\%$. In this case there is indeed a probability of about $10\%$ that the intrinsic column density distribution of DLA systems is a power law $f(N_{HI}) \propto 1/N_{HI}^{~1.95}$. In contrast, with $25 \%$ of the metals in dust - the most realistic estimate - a power law is ruled out at $99.5\%$ of confidence level. | |
| dc.description | 32 pages, 8 figures, accepted for publication in the Astrophysical Journal | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0606693 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0606693 | |
| dc.identifier | Astrophys.J.651:51-60,2006 | |
| dc.identifier | doi:10.1086/507423 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/181025 | |
| dc.subject | Astrophysics | |
| dc.title | Neutral gas density in Damped Lyman Alpha systems | |
| dc.type | text |