Astronomy and Astrophysics – Astrophysics
Scientific paper
Jun 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993a%26a...273...15w&link_type=abstract
Astronomy and Astrophysics, Vol.273, NO. 1/JUNI, P. 15, 1993
Astronomy and Astrophysics
Astrophysics
32
Scientific paper
The spectrum of the z_em_ = 2.341 quasar Q 2116-358 shows prominent clusters of absorption lines near the redshifted positions of the quasar's N V, Si IV and C IV broad emission lines at λ_obs_4140A, λ_obs_4680A and λ_obs_5180A. Two absorption systems with redshifts near z_abs_ = 1.996 and z_abs_ = 2.318 are the major contributors to these absorption lines clusters. Each system contains at least 5 separate cloud components spread over a velocity range of about 250 km s^-1^. Lines from a wide range of ionization are present. Ionization levels range from O^0^ to C^+3^ in the z_abs_ = 2.318 and z_abs_ = 1.996 systems. Models of the absorption lines suggest that the lower limit to the metal abundance in the z_abs_ = 1.996 system is 1/5 solar and it is 1/3 solar for the z_abs_ = 2.318 system. Another system, at z_abs_ = 2.307 has H I and strong N V and C IV absorption. These lines seem not to cover the QSO broad emission line region. If the absorption lines are formed in condensations within a high velocity gas outflow from the quasar, such condensation must be smaller than the nuclear line emission region of the quasar. We suggest that the z_abs_ = 2.307 system lies nearer the QSO than the system at z_abs_ = 2.318 and is directly exposed to the ionizing flux from the QSO. This latter must be attenuated by substantial HeII column density in order to explain the lower ionization degree of the z_abs_ = 2.318 system. The redshift difference between the z_abs_ = 1.996 and z_abs_ = 2.318 systems is such that the strongest carbon and silicon resonance lines of one system are spaced from the strongest lines of the other system by the doublet separation of either C IV λ1550 or N V λ1240. Additional coincidences between other transitions seem also to be present. Because close wavelength coincidences between random doublets and strong lines in an unrelated redshift system is unlikely, the existence of so many coincidences suggests a causal connection could exist between the two redshift systems. However, in both the z_abs_ = 1.996 and z_abs_ = 2.318 systems, transitions from the fine structure levels of CII, Si II and Fe II are less than 1/50 the strength of the zero volt transitions; thus if these absorbing clouds are part of a high velocity quasar wind, they must be more than ~1 kpc from the quasar nucleus.
Bergeron Jacqueline
Petitjean Patrick
Wampler Joseph E.
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