Correlated time variability of multicomponent high-velocity outflows in J162122.54+075808.4

Abstract

We present a detailed analysis of time variability of two distinct C iv broad absorption line (BAL) components seen in the spectrum of J162122.54+075808.4 (zem= 2.1394) using observations from SDSS, NTT and SALT taken at seven different epochs spanning about 15 years. The blue-BAL component (with an ejection velocity, ve ∼ 37 500 km s−1) is an emerging absorption that shows equivalent width variations and kinematic shifts consistent with acceleration. The red-BAL component (ve ∼ 15 400 km s−1) is a three component absorption. One of the components is emerging and subsequently disappearing. The two other components show kinematic shifts consistent with acceleration coupled with equivalent width variability. Interestingly, we find the kinematic shifts and equivalent width variability of the blue- and red-BAL components to be correlated. While the C iv emission line flux varies by more than 17 per cent during our monitoring period, the available light-curves (covering rest frame 1300–2300 Å) do not show more than a 0.1 mag variability in the continuum. This suggests that the variations in the ionizing flux are larger than that of the near-UV flux. However, the correlated variability seen between different BAL components cannot be explained solely by photoionization models without structural changes. In the framework of disk wind models, any changes in the radial profiles of density and/or velocity triggered either by disk instabilities or by changes in the ionizing radiation can explain our observations. High resolution spectroscopic monitoring of J1621 + 0758 is important to understand the physical conditions of the absorbing gas and thereby to constrain the parameters of disk-wind models.

Coordinated time variability of multi-phase ultra-fast outflows in J132216.25+052446.3

“…The requirement of large changes in the ionizing flux can be reconciled if we allow for the C ionizing photon flux to have larger variability compared to what we measure in the FUV range (i.e 𝐹 1640Å ). The scatter can be understood if the C ionizing photon flux has a range of values for a given 𝐹 1640Å (similar discussions in Aromal et al 2021, in the case of J1621+0758). On the other hand, it is also possible that in addition to the changes in the ionizing flux, variations in other parameters such as the covering factor (see discussions in the previous section) or changes in the gas properties could contribute to the scatter.…”

“…We show the time evolution of the C emission line rest equivalent width obtained from our continuum+Gaussian fits in It is usual procedure to interpret such a correlated variability between different BAL components and BEL equivalent widths to changes in the ionization due to quasar variability (see for example, Aromal et al 2021). Wang et al (2015) have found a correlation between variations in the equivalent widths of C emission lines and BALs in their sample.…”

“…We provide the details of these systems and their variability nature in the following sections. Continuum fits to spectra obtained in the different epochs are shown in Fig 2 . As in Aromal et al (2021), we correlate the absorption line variability with the continuum variability using available broad band photometric light curves. For this, we obtained publicly available photometric light-curves of J1322+0524 from the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS; Chambers et al 2016), the Palomar Transient Factory (PTF; Law et al 2009) and the Zwicky Transient Facility (ZTF; Bellm et al 2019a,b) surveys.…”

“…Based on the inferred covering factor (for epoch-7 when absorption lines are strongest) it is most likely that the absorbing gas is either co-spatial with or located outside the broad emission line region (typical distance of ∼ 0.09pc from the central UV source). First we construct the broad band spectral energy distribution (SED) of J1322 + 0524 using the method discussed in Aromal et al (2021) (refer to subsection 5.2.1) using the available photometric data. Then, we use the code C to simulate the thermal and ionization conditions in the absorbing gas (assumed to be a plane parallel slab of uniform density with solar metallicity) after illuminating it with the above SED from one side.…”

“…This monitoring programme has revealed several interesting BAL quasars. In Aromal et al (2021) we presented a detailed analysis of J162122.54+075808.4, that shows emergence and acceleration signatures of new BAL components at large velocity. In this paper, we present a detailed analysis of another interesting BAL QSO (J132216.25+052446.3, hereafter denoted as J1322+0524) for the following reasons: (i) Presence of a broad absorption component consisting of multiple narrow absorption features that are separated roughly by C doublet splitting.…”