Narrow-line region gas kinematics of 24 264 optically selected AGN: the radio connection

Mullaney, J.R.; Alexander, D.M.; Fine, S.; Goulding, A.D.; Harrison, C.M.; Hickox, R.C.

Abstract

Using a sample of 24 264 optically selected active galactic nuclei (AGNs) from the SDSS DR7 data base, we characterize how the profile of the [O III] λ5007 emission line relates to bolometric luminosity (LAGN), Eddington ratio, radio loudness, radio luminosity (L1.4 GHz) and optical class (i.e. broad/narrow-line Seyfert 1, type 2) to determine what drives the kinematics of this kpc-scale line emitting gas. First, we use spectral stacking to characterize how the average [O III] λ5007 profile changes as a function of these five variables. After accounting for the known correlation between LAGN and L1.4 GHz, we report that L1.4 GHz has the strongest influence on the [O III] λ5007 profile, with AGNs of moderate radio luminosity (L1.4 GHz = 1023–1025 W Hz−1) having the broadest [O III] λ5007 profiles. Conversely, we find only a modest change in the [O III] λ5007 profile with increasing radio loudness and find no significant difference between the [O III] λ5007 profiles of broad- and narrow-line Seyfert 1s. When binned according to Eddington ratio, only the AGNs in our highest bin (i.e. >0.3) show any signs of having broadened [O III] λ5007 profiles, although the small numbers of such extreme AGNs in our sample mean we cannot rule out that other processes (e.g. radio jets) are responsible for this broadening. The [O III] λ5007 profiles of type 1 and type 2 AGNs show the same trends in terms of line width, but type 1 AGNs display a much stronger ‘blue wing’, which we interpret as evidence of outflowing ionized gas. We perform multicomponent fitting to the Hβ, [O III] λλ4959, 5007, [N II] λλ6548, 6584 and Hα lines for all the AGNs in our sample to calculate the proportions of AGNs with broad [O III] λ5007 profiles. The individual fits confirm the results from our stacked spectra; AGNs with L1.4 GHz > 1023 W Hz−1 are roughly five times more likely to have extremely broad [O III] λ5007 lines (full width at half-maximum, FWHMAvg > 1000 km s−1) compared to lower L1.4 GHz AGNs, and the width of the [O III] λ5007 line peaks in moderate-radio-luminosity AGNs (L1.4 GHz ∼ 1024 W Hz−1). Our results are consistent with the most disturbed gas kinematics being induced by compact radio cores (rather than powerful radio jets), although broadened [O III] λ5007 lines are also present, but much rarer, in low-L1.4 GHz systems. Our catalogue of multicomponent fits is freely available as an online resource for statistical studies of the kinematics and luminosities of the narrow- and broad-line AGN regions and the identification of potential targets for follow-up observations at http://sites.google.com/site/sdssalpaka.

Citation

Mullaney, J., Alexander, D., Fine, S., Goulding, A., Harrison, C., & Hickox, R. (2013). Narrow-line region gas kinematics of 24 264 optically selected AGN: the radio connection. Monthly Notices of the Royal Astronomical Society, 433(1), 622-638. https://doi.org/10.1093/mnras/stt751

• Journal Article Type: Article
• Publication Date: Jul 21, 2013
• Deposit Date: Jun 21, 2013
• Publicly Available Date: Jun 19, 2014
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 433
• Issue: 1
• Pages: 622-638
• DOI: https://doi.org/10.1093/mnras/stt751
• Keywords: Catalogues, ISM: kinematics and dynamics, Galaxies: active, Quasars: emission lines, Radio continuum: galaxies
• Public URL: https://durham-repository.worktribe.com/output/1450709