Identification Of Outflows And Candidate Dual Active Galactic Nuclei In SDSS Quasars At Z=0.8-1.6




Barrows, R. Scott
Lacy, Claud H. Sandberg
Kennefick, Julia
Comerford, Julia M.
Kennefick, Daniel
Berrier, Joel C.

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We present a sample of 131 quasars from the Sloan Digital Sky Survey at redshifts 0.8 < z < 1.6 with double peaks in either of the high-ionization narrow emission lines [Ne V]lambda 3426 or [Ne III]lambda 3869. These sources were selected with the intention of identifying high-redshift analogs of the z < 0.8 active galactic nuclei (AGNs) with double-peaked [O III]lambda 5007 lines, which might represent AGN outflows or dual AGNs. Lines of high ionization potential are believed to originate in the inner, highly photoionized portion of the narrow line region, and we exploit this assumption to investigate the possible kinematic origins of the double-peaked lines. For comparison, we measure the [Ne V]lambda 3426 and [Ne III]lambda 3869 double peaks in low-redshift (z < 0.8) [O III]-selected sources. We find that [Ne V]lambda 3426 and [Ne III]lambda 3869 show a correlation between line splitting and line width similar to that of [O III]lambda 5007 in other studies, and the velocity splittings are correlated with the quasar Eddington ratio. These results suggest an outflow origin for at least a subset of the double peaks, allowing us to study the high-ionization gas kinematics around quasars. However, we find that a non-negligible fraction of our sample show no evidence for an ionization stratification. For these sources, the outflow scenario is less compelling, leaving the dual AGN scenario as a viable possibility. Finally, we find that our sample shows an anti-correlation between the velocity-offset ratio and luminosity ratio of the components, which is a potential dynamical argument for the presence of dual AGNs. Therefore, this study serves as a first attempt at extending the selection of candidate dual AGNs to higher redshifts.



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Barrows, R. Scott, Claud H. Sandberg Lacy, Julia Kennefick, Julia M. Comerford, Daniel Kennefick, and Joel C. Berrier. "Identification of Outflows and Candidate Dual Active Galactic Nuclei in SDSS Quasars at z= 0.8-1.6." The Astrophysical Journal, Vol. 769, No. 2 (Jun., 2013): 95.