An international team of astronomers recently conducted a study on Markarian 1018, an active galaxy with an energetic core known as an active galactic nucleus (AGN). AGNs are classified into Type 1 and Type 2 based on emission line features. Markarian 1018 is a rare changing-look (CL) AGN that transitions between these types.
Using high-cadence optical monitoring with STELLA telescopes, the astronomers observed an impressive outburst in mid-2020. The outburst was asymmetric, with a rapid rise of less than 100 days and a slower decline of at least 200 days. Interestingly, the decline was linear, ruling out a tidal disruption event (TDE) as the cause.
To understand the outburst better, the team analyzed X-ray and ultraviolet observations but found no intrinsic absorption, eliminating the possibility of temporary obscuring material causing the increase in emission.
The results indicate that the outburst was likely caused by a drastic, short-term increase in the accretion rate, with several possible explanations, such as chaotic cold accretion (CCA), binary black hole (BBH), or a recoiling supermassive black hole (rSMBH).
In summary, the study sheds more light on the nature of the outburst in Markarian 1018, a fascinating active galaxy with a unique changing-look AGN.