Volume 420, Number 3, June IV 2004
|Page(s)||889 - 897|
|Published online||04 June 2004|
Extreme gas properties in the most distant quasars
INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
2 INAF - Telescopio Nazionale Galileo, Calle Alvarez de Abreu, 70, 38700 Santa Cruz de La Palma, Spain
3 Istituto di Radioastronomia, sezione di Firenze - Largo E. Fermi 5, 50125 Firenze, Italy
4 Instituto Nacional de Astrofísica Óptica y Electronica, Puebla, Luis Enrique Erro 1, Tonantzintla, Puebla 72840, Mexico
Corresponding author: R. Maiolino, email@example.com
Accepted: 15 March 2004
We present near-IR, low resolution spectra of eight of the most distant quasars known, with redshifts in the range . Half of these quasars are characterized by deep, broad and blueshifted absorption features associated with both high and low ionization species (CIV, SiIV, AlIII, MgII), i.e. they belong to the class of Broad Absorption Line (BAL) quasars, which are associated with powerful outflows of dense gas. Although the sample is small, the large fraction of BAL quasars, the depth and ionization state of the absorption features suggest that these most distant quasars are surrounded by a much larger amount of dense gas than lower redshift () quasars. The possible interpretation in terms of extremely high accretion rates and the association with the early formation of quasars and of their host galaxies is discussed. The absorption properties of the dust, associated with the gas along the line of sight, appear different with respect to lower redshift quasars, possibly indicating different dust physics at these highest redshifts.
Key words: galaxies: active / galaxies: evolution / galaxies: high-redshift / galaxies: quasars: absorption lines / galaxies: quasars: general
© ESO, 2004
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