Probing quasar winds using intrinsic narrow absorption lines. (2019)
Keywords :
accretion, accretion discs - galaxies active - (galaxies:) quasars: absorption lines - (galaxies:) quasars: general
Abstract:We use the spectra of 73 quasars (1.5=<z=<5) from the VLT UVES archive to catalogue and study narrow absorption lines (NALs) that are physically associated with (intrinsic to) the quasars. We identify 410 NAL systems containing CIV, NV, and/or SiIV doublets. Based on the assumption that only systems intrinsic to the quasar can exhibit partial coverage of the background source(s), we identify 34 reliably intrinsic NAL systems and 11 systems that are potentially intrinsic, as well as 4 mini-broad absorption lines (BALs) and 1 BAL. The minimum fraction of quasars with at least one intrinsic system is shown to be 38 per cent. We identify intrinsic NALs with a wide range of properties, including apparent ejection velocity, coverage fraction,
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In this paper, we use the high-resolution (R~45000) spectra of 73
quasars from the VLT UVES archive, with a redshift range 1.4<z<4.7.
These are a subset of the 81 quasars found in the archive before 2006
June that were used for the Narayanan et al. (2007ApJ...660.1093N,
Cat. J/ApJ/660/1093) survey of weak MgII absorbers, excluding the 8
quasars at z<1.4 for which the NV emission line would not be covered.
Our sample also excluded known BAL quasars, though one BAL was found,
and exhibits a preference for optically bright quasars that allow
high-resolution observations. As the presence of BALs gives an
enhanced probability of finding CIV associated absorption lines
(Ganguly et al. 2001ApJ...549..133G), the exclusion of BAL quasars may
bias our sample against intrinsic NALs. However, the properties of the
intrinsic NALs in our sample of quasars are unlikely to be
significantly different from the NALs found towards BAL quasars.
Since we aim to determine whether the intrinsic NAL incidence rate and
physical properties depend on quasar properties, we present relevant
quasar properties in Table 1.
The spectra of the 73 quasars, retrieved from the ESO archive, were
reduced with the eso-midas ECHELLE/UVES package, as described in
Narayanan et al. (2007ApJ...660.1093N, Cat. J/ApJ/660/1093). After
wavelength calibration, we applied heliocentric velocity corrections
and rebinned the spectra to 0.03{AA}. We then normalized the spectra
by applying a continuum fit, determined using the IRAF SFIT procedure.
