On the origin of the dramatic spectral variability of WPVS 007

Abstract

We report the discovery of large-amplitude mid-infrared variabilities (MIR; ∼ 0.3 mag) in the Wide-field Infrared Survey Explorer W1 and W2 bands of the low-luminosity narrow-line Seyfert 1 galaxy WPVS 007, which exhibits prominent and varying broadabsorption lines (BALs) with blueshifted velocity up to ∼ 14000 km s −1 . The observed significant MIR variability, the UV to optical color variabilities in the Swift bands that deviate from the predictions of pure dust attenuation models, and the fact that Swift light curves can be well fitted by the stochastic AGN variability model suggest that its observed flux variabilities in UV-optical-MIR bands should be intrinsic, rather than owing to variable dust extinction. Furthermore, the variations of BAL features (i.e., trough strength and maximum velocity) and continuum luminosity are concordant. Therefore, we propose that the BAL variability observed in WPVS 007 is likely induced by the intrinsic ionizing continuum variation, alternative to the rotating-torus model proposed in a previous work. The BAL gas in WPVS 007 might be in the lowionization state as traced by its weak N v BAL feature; as the ionizing continuum strengthens, the C iv and Si iv column densities also increase, resulting in stronger BALs and the emergence of high-velocity components of the outflow. The outflow launch radius might be as small as ∼ 8 × 10 −4 pc under the assumption of being radiatively driven, but a large-scale origin (e.g., torus) cannot be fully excluded because of the unknown effects from additional factors, e.g., the magnetic field.

Piercing through Highly Obscured and Compton-thick AGNs in the Chandra Deep Fields. II. Are Highly Obscured AGNs the Missing Link in the Merger-triggered AGN–Galaxy Coevolution Models?

“…Blueshifted absorption lines detected in AGNs have been widely interpreted as an indicator of outflowing materials (e.g., Gibson et al 2009;Filiz et al 2013;Li et al 2019a), which have long served as crucial ingredients in the evolutionary models that are responsible for transforming AGN types (i.e., from type 2 to type 1 or X-ray obscured to unobscured) and quenching star formation; see, e.g., King & Pounds (2015) for a review. A possible way to study whether our highly obscured AGNs are experiencing a blow-out phase and may eventually become unobscured AGNs is to investigate whether they are in the "forbidden" outflow region in the N H versus l Edd diagram as defined in Fabian et al (2008).…”

Piercing through Highly Obscured and Compton-thick AGNs in the Chandra Deep Fields. II. Are Highly Obscured AGNs the Missing Link in the Merger-Triggered AGN-Galaxy Coevolution Models?

“…Blueshifted absorption lines detected in AGNs have been widely interpreted as an indicator of outflowing materials (e.g., Gibson et al 2009;Filiz Ak et al 2013;Li et al 2019a), which have long been served as crucial ingredients in the evolutionary models that are responsible for transforming AGN types (i.e., from type 2 to type 1 or X-ray obscured to unobscured) and quenching star formation (see, e.g., King & Pounds 2015 for a review). A possible way to study whether our highly obscured AGNs are experiencing a blow-out phase and may eventually become unobscured AGNs is to investigate whether they are in the "forbidden" outflow region in the N H vs. λ Edd diagram as defined in Fabian 12, where the distribution of λ Edd is also shown.…”

Investigating the Origin of the Absorption-line Variability in the Narrow-line Seyfert 1 Galaxy WPVS 007

“…Derived parameters including column density, radial distance to the outflow, mass outflow rate, and kinetic luminosity are given in Section 5. Lastly, in Section 6, we revisit the Li et al (2019) conclusions and present our interpretation of the cause of the outflow variability from the results of our analysis. Throughout this paper, we adopt a flat Universe Lambda cold dark matter (ΛCDM) cosmology with H 0 = 67.7 km s −1 Mpc −1 , Ω M = 0.31, and Ω Λ = 0.69 (Planck Collaboration et al 2020).…”

“…More recently, Li et al (2019) presented a detailed comparison of Wide-field Infrared Survey Explorer (WISE) mid-infrared photometry and the UV photometry from Swift. They attribute the variations in both data sets to changes in the accretion-disk luminosity and note that the brightness changes seen by WISE lag behind those seen in Swift by roughly 600 days as expected from the physical size of the UV and midinfrared emitting regions at their respective wavelengths.…”