The Intrinsic Absorber in QSO 2359−1241: Keck andHubble Space TelescopeObservations

Abstract

We present detailed analyses of the absorption spectrum seen in QSO 2359-1241. Keck HIRES data reveal absorption from twenty transitions arising from: He i, Mg i, Mg ii, Ca ii, and Fe ii. HST data show broad absorption lines (BALs) from Al iii λ1857, C iv λ1549, Si iv λ1397, and N v λ1240. Absorption from excited Fe ii states constrains the temperature of the absorber to 2000 < ∼ T < ∼ 10, 000 K and puts a lower limit of 10 5 cm −3 on the electron number density. Saturation diagnostics show that the real column densities of He i and Fe ii can be determined, allowing to derive meaningful constraints on the ionization equilibrium and abundances in the flow. The ionization parameter is constrained by the iron, helium and magnesium data to −3.0 < ∼ log(U) < ∼ −2.5 and the observed column densities can be reproduced without assuming departure from solar abundances. From comparison of the He i and Fe ii absorption features we infer that the outflow seen in QSO 2359-1241 is not shielded by a hydrogen ionization front and therefore that the existence of low-ionization species in the outflow (e.g., Mg ii, Al iii, Fe ii) does not necessitate the existence of such a front. We find that the velocity width of the absorption systematically increases as a function of ionization and to a lesser extent with abundance. Complementary analyses of the radio and polarization properties of the object are discussed in a companion paper (Brotherton et al. 2000).

On the Column Density of AGN Outflows: The Case of NGC 5548

“…In the last few years, our group (Arav 1997 ;Arav et al 1999a ;Arav et al 1999b ; Arav et al 2001) and others (Barlow 1997 ;Telfer et al 1998 ;Churchill et al 1999 ;Ganguly et al 1999) have shown that, in quasar outÑows, most lines are saturated, even when not black. We have also shown that, in many cases, the shapes of the troughs are almost entirely due to changes in the line-of-sight covering as a function of velocity, rather than to di †erences in optical depth (Arav et al 1999b ;de Kool et al 2001 ;Arav et al 2001 ; we elaborate on this point below). As a consequence, the column densities inferred from the depths of the troughs are only lower limits.…”

Intrinsic Absorption in the QSO FIRST J121442.3+280329

“…The expected positions of the strongest resonance line of Fe I at 2484 and the Mg I resonance line A at 2853 are indicated in Figure 4. Absorption lines from A the 23S state of He I have been detected in some intrinsic QSO absorption line sytems (Arav et al 2001a). The position of the strongest He I 23S line in the wavelength range covered by the spectrum (3189 is again indicated in A ) Figure 4.…”

“…Using several low-ionization lines from Fe II, Mg I, and Si II, they derived outÑow densities of and a very large distance of the 103 cm~3 \ n H \ 105 cm~3 absorbers on the order of 28 kpc. Arav et al (2001a) studied intrinsic absorption in the QSO 2359[1241, deriving a low-ionization parameter [3.0 \ log U \ [2.5 and a lower limit on the hydrogen density of log n H [ 5.0. The two most detailed analyses of strong intrinsic QSO Fe II absorption that we are aware of is the analysis of Q0059[2735 by WCP and the analysis of FBQS 1044]3656 by de Kool et al (2001).…”

Polar Outflows in Six Broad Absorption Line Quasars

“…Many Fe ii absorption features are also detected redward of Mg ii, as well as the neutral helium absorption triplet He i kk2946, 3189, 3890, which can be used as powerful diagnostics of H i column density (Arav et al 2001 and references therein). Only a few quasars have been found showing the He i absorption lines so far (e.g., Anderson 1974;Arav et al 2001;Hall et al 2002).…”