Electron temperature fluctuations in Seyfert galaxies

TL;DR

This study measures electron temperature fluctuations in the inner regions of three Seyfert galaxies using Gemini GMOS-IFU data, revealing significant temperature variations that could affect chemical abundance estimates in active galactic nuclei.

Contribution

First measurement of the temperature fluctuation parameter in the plane of the sky for Seyfert galaxies, highlighting its potential impact on abundance calculations in AGNs.

Findings

Temperature fluctuation parameter $t_A^2$ ranges from 0.015 to 0.135.

$t_A^2$ values are comparable or larger than those in star-forming regions.

Temperature fluctuations may significantly influence chemical abundance determinations in AGNs.

Abstract

We use Gemini GMOS-IFU observations of three luminous nearby Seyfert galaxies (Mrk79, Mrk348 and Mrk607) to estimate the electron temperature ($T_{\rm e}$) fluctuations in the inner 0.4-1.1 kpc region of these galaxies. Based on $T_{\rm e}$ determinations through the [O III]$\lambda5007$/$\lambda4363$ emission line ratio of each spaxel, temperature variations are quantified by computing the integrated value of the temperature fluctuation parameter ($t^{\rm 2}$) projected in the plane of the sky $t_{\rm A}^{\rm 2}$, for the first time in Active Galactic Nuclei. We find $t_{\rm A}^{\rm 2}$ values of 0.135, 0.039, and 0.015 for Mrk79, Mrk348, and Mrk607, respectively, which are of the same order or larger than the maximum values reported in star-forming regions and planetary nebulae. Taking into account that $t_{\rm A}^{\rm 2}$ should be considered a lower limit of the total $t^2$ in the nebular volume, the results suggest that the impact of such fluctuations on chemical abundance determinations can be important in some AGNs.