Abstract
ABSTRACT Chemical abundance determinations in Low-Ionization Nuclear Emission-line Regions (LINERs) are especially complex and uncertain because the nature of the ionizing source of this kind of object is unknown. In this work, we study the oxygen abundance in relation to the hydrogen abundance (O/H) of the gas phase of the UGC 4805 LINER nucleus. Optical spectroscopic data from the Mapping Nearby Galaxies survey was employed to derive the O/H abundance of the UGC 4805 nucleus based on the extrapolation of the disc abundance gradient, on calibrations between O/H abundance and strong emission-lines for active galactic nuclei (AGNs) as well as on photoionization models built with the Cloudy code, assuming gas accretion into a black hole (AGN) and post-asymptotic giant branch (p-AGB) stars with different effective temperatures. We found that abundance gradient extrapolations, AGN calibrations, AGN, and p-AGB photoionization models produce similar O/H values for the UGC 4805 nucleus and similar ionization parameter values. The study demonstrated that the methods used to estimate the O/H abundance using nuclear emission-line ratios produce reliable results, which are in agreement with the O/H values obtained from the independent method of galactic metallicity gradient extrapolation. Finally, the results from the WHAN diagram combined with the fact that the high excitation level of the gas has to be maintained at kpc scales, we suggest that the main ionizing source of the UGC 4805 nucleus probably has a stellar origin rather than an AGN.
Highlights
Determinations of the chemical abundances of Active Galactic Nuclei (AGNs) and Star-Forming regions (SFs) are essential for understanding the chemical evolution of galaxies and, of the Universe.Among the heavy elements present in the gas phase of AGNs and SFs (e.g., O, N, S), oxygen is the element with more accurate abundance determinations
We study the oxygen abundance in relation to the hydrogen abundance (O/H) of the gas phase of the UGC 4805 Line Regions (LINERs) nucleus
We present a detailed analysis of the spiral galaxy UGC 4805, an object with a classical LINER nuclear emission and with the largest number of star-forming emission spaxels along the disk
Summary
Among the heavy elements present in the gas phase of AGNs and SFs (e.g., O, N, S), oxygen is the element with more accurate abundance determinations. This is because prominent emissionlines from the main ionic stages of oxygen can be detected in the optical spectra of these objects, making it a good tracer of the metallicity (e.g., Kennicutt et al 2003; Hägele et al 2008; Dors et al 2015, 2020a). For AGNs, chemical abundance determinations are preferably carried out in Narrow Line Regions (NLRs) of Seyfert 2 nuclei due to the relatively low velocity
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
