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Gravitational Lensing by Damped LY alpha Absorbers
Smette, A.; Claeskens, Jean-François; Surdej, Jean
1999In Carilli, C. L.; Radford, S. J. E.; Menten, K. M. et al. (Eds.) Highly Redshifted Radio Lines, ASP Conf. Series Vol. 156
 

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Keywords :
(COSMOLOGY:) OBSERVATIONS; (COSMOLOGY:) DARK MATTER; (COSMOLOGY:) GRAVITATIONAL LENSING; (GALAXIES:) QUASARS: ABSORPTION LINES; GALAXIES: EVOLUTION; GALAXIES: SPIRAL
Abstract :
[en] Spiral galaxies are thought to be the main responsible for the damped Ly-alpha (DLA) systems seen in QSO spectra. They can also act as gravitational lenses, affecting quantities derived in DLA surveys. Assuming that z > 0 spiral galaxies are similar to local ones, we find that, at z 0.5, the number density of DLA systems may be over-estimated by up to 90% and the HI cosmological density (Omega[SUB]HI[/SUB]) by up to 170% in a survey using bright b[SUB]q[/SUB] = 16, z[SUB]q[/SUB] ga 2 QSOs and in the absence of important extinction by dust. Applying our model to existing surveys, we find that Omega[SUB]HI[/SUB] is significantly over-estimated only in the z < 1.7 ones (by 34%). Furthermore, statistical tests indicate that these surveys are indeed affected by gravitational lensing at a 2.3% confidence level. If luminosity functions for flat-spectrum radio-sources and optically selected QSOs are similar in shape and slopes, similar Gling effects should affect surveys for 21cm absorbers using bright, high-z flat-spectrum radio-sources.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Smette, A.;  NASA-GSFC, Code 681, Greenbelt, MD 20771, USA
Claeskens, Jean-François ;  Institut d'Astrophysique et de Geophysique, Universite de Liege, Avenue de Cointe, 5, B-4000 Liege, Belgium, and FNRS, Belgium
Surdej, Jean  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Language :
English
Title :
Gravitational Lensing by Damped LY alpha Absorbers
Publication date :
1999
Event name :
Highly Redshifted Radio Lines, ASP Conf. Series Vol. 156
By request :
Yes
Audience :
International
Main work title :
Highly Redshifted Radio Lines, ASP Conf. Series Vol. 156
Author, co-author :
Carilli, C. L.
Radford, S. J. E.
Menten, K. M.
Langston, G. I.
ISBN/EAN :
1-886733-76-7
Collection name :
ASP Conf. Series Vol. 156
Pages :
147-151
Available on ORBi :
since 22 October 2009

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