Extreme line profile variations in the repeating changing-look active galactic nucleus IRAS23226-3843
Abstract
IRAS23226-3843 has been identified as a highly variable Seyfert galaxy and even as a changing-look active galactic nucleus based on optical spectra. Here we present follow-up observations - taken over the past five years - for examining the ongoing photometric and spectral variations in this remarkable galaxy. We carried out SWIFT observations of IRAS23226-3843 together with new optical spectra taken in 2023 and 2024. In parallel we investigate ASAS-SN photometric data from 2014 till 2025. IRAS23226-3843 stayed on a high continuum flux level in the X-ray as well as in the optical since a historic outburst in 2019. However, it shows strong short-term variations on timescales of a few months. Densely sampled ASAS-SN V-band continuum data from 2014 till 2025 confirm that behavior. IRAS23226-3843 switched from a clear Seyfert 1 type in December 2019 to a Seyfert 1.9/2 type in July 2020 based on its optical spectra. Afterward, it again became a Seyfert 1 type with symmetric broad single-peaked Balmer line profiles in January 2023. These spectra prove the repeating changing-look character of the galaxy.IRAS23226-3843 exhibits extreme high Balmer decrements Ha\Hb based on their broad line components. The Balmer decrement values are on the order of 10. IRAS23226-3843 successively showed all types of broad line Balmer profiles during the past 25 years over periods of many years: asymmetric single-peaked, double-peaked, as well as single-peaked and symmetric profiles in addition to its Seyfert 1.9/2 transition. These variations are not clearly correlated with continuum and line intensity variations.
Keywords
Cite
@article{arxiv.2601.15979,
title = {Extreme line profile variations in the repeating changing-look active galactic nucleus IRAS23226-3843},
author = {Wolfram Kollatschny and Dirk Grupe and Hartmut Winkler and Malte A. Probst and Martin W. Ochmann and Amon Poenitzsch and Norbert Schartel and Salem Wolsing and Stefanie Komossa and Stephen B. Potter},
journal= {arXiv preprint arXiv:2601.15979},
year = {2026}
}
Comments
13 pages, 8 figures, Astronomy & Astrophysics in press