Publication: NGC 7469 as seen by MEGARA: new results from high-resolution IFU spectroscopy
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2020-04
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Oxford University Press.
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Abstract
We present our analysis of high-resolution (R ∼ 20 000) GTC/MEGARA integral-field unit spectroscopic observations, obtained during the commissioning run, in the inner region (12.5 arcsec × 11.3 arcsec) of the active galaxy NGC 7469, at spatial scales of 0.62 arcsec. We explore the kinematics, dynamics, ionization mechanisms, and oxygen abundances of the ionized gas, by modelling the H α-[N II] emission lines at high signal-to-noise (> 15) with multiple Gaussian components. MEGARA observations reveal, for the first time for NGC 7469, the presence of a very thin (20 pc) ionized gas disc supported by rotation (V/σ = 4.3), embedded in a thicker (222 pc), dynamically hotter (V/σ = 1.3) one. These discs nearly corotate with similar peak-to-peak velocities (163 versus 137 km s^(−1)), but with different average velocity dispersion (38 ± 1 versus 108 ± 4 km s^(−1)). The kinematics of both discs could be possibly perturbed by star-forming regions. We interpret the morphology and the kinematics of a third (broader) component (σ > 250 km s^(−1)) as suggestive of the presence of non-rotational turbulent motions possibly associated either to an outflow or to the lense. For the narrow component, the [N II]/H α ratios point to the star-formation as the dominant mechanism of ionization, being consistent with ionization from shocks in the case of the intermediate component. All components have roughly solar metallicity. In the nuclear region of NGC 7469, at r ≤ 1.85 arcsec, a very broad (FWHM = 2590 km s^(−1)) H α component is contributing (41 per cent) to the global H α-[N II] profile, being originated in the (unresolved) broad line region of the Seyfert 1.5 nucleus of NGC 7469.
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© 2020 The Author(s). Artículo firmado por 16 autores. This paper is based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. This work is based on data obtained with MEGARA instrument, funded by European Regional Development Funds (ERDF), trough Programa Operativo Canarias FEDER 2014- 2020.
SC, IM, JM, and LHM acknowledge financial support by the Spanish Ministry of Economy and Competitiveness (MEC) under grant no. AYA2016-76682-C3. We also acknowledge financial support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709).
AGdP, JG, ACM, SP, and NC acknowledge financial support from the Spanish MEC under grant no. AYA2016-75808-R.
This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We acknowledge the usage of the HyperLeda database (http://leda.univ-lyon1.fr).
This paper made use of the plotting package JMAPLOT, developed by Jesús Maíz-Apellániz available at: http://jmaiz.iaa.es/software/ jmaplot/ current/html/jmaplot overview.html.
The authors acknowledge the anonymous referee for her/his instructive comments that helped to improve the presentation of this paper.
SC thanks R. Amorin and R. Schödel for their useful comments.