Observations of Outflowing Ultraviolet Absorbers in NGC 4051 With the Cosmic Origins Spectrograph

Abstract

We present new Hubble Space Telescope (HST)/Cosmic Origins Spectrograph (COS) observations of the narrowline Seyfert 1 galaxy NGC 4051. These data were obtained as part of a coordinated observing program including X-ray observations with the Chandra/High Energy Transmission Grating (HETG) spectrometer and Suzaku. We detected nine kinematic components of UV absorption, which were previously identified using the HST/Space Telescope Imaging Spectrograph (STIS). None of the absorption components showed evidence for changes in column density or profile within the ∼10 yr between the STIS and COS observations, which we interpret as evidence of (1) saturation, for the stronger components, or (2) very low densities, i.e., n H < 1 cm −3 , for the weaker components. After applying a + 200 km s −1 offset to the HETG spectrum, we found that the radial velocities of the UV absorbers lay within the O vii profile. Based on photoionization models, we suggest that, while UV components 2, 5, and 7 produce significant O vii absorption, the bulk of the X-ray absorption detected in the HETG analysis occurs in more highly ionized gas. Moreover, the mass-loss rate is dominated by high-ionization gas which lacks a significant UV footprint.

Direct Observation of the Broad Line Region in X-Rays during the Low State of NGC 4051

“…This reinforces the evidence for an X-ray component in a stratified BLR. The mean C +3 profile from Peterson et al (2000) is similarly broad, though it is heavily absorbed, as seen in Kraemer et al (2012).…”

On the Observational Difference Between the Accretion Disk-Corona Connections among Super- and Sub-Eddington Accreting Active Galactic Nuclei

“…(2) Since we aim to explore the intrinsic X-ray and UV/optical properties of our sample, objects affected by heavy absorption in the X-ray and UV/optical bands were excluded. We discarded 11 objects in total, nine of which are well-studied objects (PG 1700 + 518, Mrk 486, NGC 4051, NGC 4151, NGC 3516, NGC 3227, NGC 3783, Mrk 5273, and MCG-6-30-15) with X-ray emission affected by ionized and/or neutral absorption related to outflows, and some of them also show continuum reddening or broad absorption lines (BALs) in their UV spectra (e.g., Pounds et al 2004;Kraemer et al 2005Kraemer et al , 2006Kraemer et al , 2012Cappi et al 2006;Ballo et al 2008Ballo et al , 2011Turner et al 2011;Beuchert et al 2015;Pahari et al 2017;Dunn et al 2018). A super-Eddington accreting AGN, Mrk 202, shows an unusually flat 2-10 keV spectrum and an absorption feature prominent in the < 2 keV spectrum, so that it was also excluded.…”

Determining Inclinations of Active Galactic Nuclei via Their Narrow-Line Region Kinematics. Ii. Correlation With Observed Properties

“…The ionic column density of each absorption line is then obtained by integrating the optical depth across the line profile (Crenshaw et al 2003). These ionic column densities are used to determine the ionization parameter (ratio of ionizing photon density to gas density, U) and N H (= N HI + N HII ) via CLOUDY photoionization modeling (Kraemer et al 2009(Kraemer et al , 2012. The listed N H values for each Sy 1 in our sample are the summed column densities across all absorption components.…”