EDP Sciences
Free access
Issue
A&A
Volume 386, Number 3, May II 2002
Page(s) 865 - 868
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20020321


A&A 386, 865-868 (2002)
DOI: 10.1051/0004-6361:20020321

Dusty haloes of galaxies at intermediate redshifts

P. Teerikorpi

Tuorla Observatory, 21500 Piikkiö, Finland

(Received 10 January 2002 / Accepted 20 February 2002 )

Abstract
The presence and amount of dust in the halo matter producing narrow metal line absorption systems is still uncertain. We consider the parameter $\Sigma_{\rm a} = \sum (1+z_{\rm a})$, summed over the detected aborption line system redshifts $z_{\rm a}$, and ask whether radio-loud quasars at z < 2 and with a large value of the parameter $\Sigma_{\rm a}$ are redder in the B-V colour than those with a smaller $\Sigma_{\rm a}$. This is anticipated if the absorption lines originate in sites which contain "normal" dust causing selective extinction. The answer is positive, and a mean intrinsic reddening e0 per halo is consistent with $\approx$0.05, or about 0.2  B-mag extinction, roughly as expected.


Key words: quasars: absorption lines -- galaxies: haloes -- ISM: dust

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