A century of change: new changing-look event in Mrk 1018's past

Thomas Dunn; Rebecca McElroy; Mirko Krumpe; Scott M. Croom; Massimo Gaspari; Miguel Perez-Torres; Michael Cowley; Osase Omoruyi; Grant Tremblay; Mainak Singha

arXiv · 2510.25156

A century of change: new changing-look event in Mrk 1018's past

Thomas Dunn·Rebecca McElroy·Mirko Krumpe·Scott M. Croom·Massimo Gaspari·Miguel Perez-Torres·Michael Cowley·Osase Omoruyi·Grant Tremblay·Mainak Singha

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Abstract

We investigate the long-term variability of the known Changing Look Active Galactic Nuclei (CL AGN) Mrk 1018, whose second change we discovered as part of the Close AGN Reference Survey (CARS). Collating over a hundred years worth of photometry from scanned photographic plates and five modern surveys we find a historic outburst between ~1935-1960, with variation in Johnson B magnitude of ~0.8 that is consistent with Mrk 1018's brightness before and after its latest changing look event in the early 2010s. Using the combined modern and historic data, a Generalised Lomb-Scargle suggests broad feature with P = 29-47 years. Its width and stability across tests, as well as the turn-on speed and bright phase duration of the historic event suggests a timescale associated with long-term modulation, such as via rapid flickering in the accretion rate caused by the Chaotic Cold Accretion model rather than a strictly periodic CL mechanism driving changes in Mrk 1018. We also use the modern photometry to constrain Mrk 1018's latest turn-off duration to less than ~1.9 years, providing further support for a CL mechanism with rapid transition timescales, such as a changing mode of accretion.

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Thomas Dunn, Rebecca McElroy, Mirko Krumpe, Scott M. Croom, Massimo Gaspari, Miguel Perez-Torres, Michael Cowley, Osase Omoruyi, Grant Tremblay, Mainak Singha. 2025-10-29. A century of change: new changing-look event in Mrk 1018's past. https://arxiv.org/abs/2510.25156

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