An AMUSING look at the host of the periodic nuclear transient ASASSN-14ko reveals a second AGN. Issue 4 (22nd July 2021)

• Record Type: Journal Article
• Authors: Tucker, M A; Shappee, B J; Hinkle, J T; Neustadt, J M M; Eracleous, M; Kochanek, C S; Prieto, J L; Payne, A V; Galbany, L; Anderson, J P; Auchettl, K; Auge, C; Holoien, Thomas W-S
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 506:Issue 4(2021)
• Page Start: 6014
• Page End: 6028
• Publication Date: 2021-07-22
• Subjects: ISM: bubbles -- galaxies: active -- galaxies: individual: ESO 253−G003 -- galaxies: kinematics and dynamics -- galaxies: nuclei; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab2085
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present Multi-Unit Spectroscopic Explorer (MUSE) integral-field spectroscopy of ESO 253−G003, which hosts a known active galactic nucleus (AGN) and the periodic nuclear transient ASASSN-14ko, observed as part of the All-weather MUse Supernova Integral-field of Nearby Galaxies survey. The MUSE observations reveal that the inner region hosts two AGN separated by $1.4\pm 0.1~\rm {kpc}$ (≈1${_{.}^{\prime\prime}}$ 7). The brighter nucleus has asymmetric broad permitted emission-line profiles and is associated with the archival AGN designation. The fainter nucleus does not have a broad emission-line component but exhibits other AGN characteristics, including $\hbox{$v_{\rm {FWHM}}$} \approx 700~\hbox{km~s$^{-1}$}$ forbidden line emission, $\rm{\log _{10}(\rm{[O\, \small {III}]}/\rm{H\beta})} \approx 1.1$, and high-excitation potential emission lines, such as [Fe vii ] λ6086 and He ii λ4686. The host galaxy exhibits a disturbed morphology with large kpc-scale tidal features, potential outflows from both nuclei, and a likely superbubble. A circular relativistic disc model cannot reproduce the asymmetric broad emission-line profiles in the brighter nucleus, but two non-axisymmetric disc models provide good fits to the broad emission-line profiles: an elliptical disc model and a circular disc + spiral arm model. Implications for the periodic nuclear transient ASASSN-14ko are discussed.