Study investigates recent outburst in the active galaxy Markarian 1018

A global group of astronomers has carried out high-cadence optical monitoring of an energetic galaxy referred to as Markarian 1018. Outcomes of the observational marketing campaign, revealed July 26 on the pre-print server arXiv, shed extra mild on the character of the latest outburst on this galaxy.

An active galactic nucleus (AGN) is a compact area on the heart of a galaxy, extra luminous than the encompassing galaxy mild. AGNs are very energetic due both to the presence of a black hole or star formation exercise on the core of the galaxy.

Astronomers typically divide AGNs into two teams primarily based on emission line options. Sort 1 AGNs present broad and slim emission traces, whereas solely slim emission traces are current in Sort 2 AGNs. Nevertheless, observations revealed that some AGNs transition between completely different spectral varieties and they’re referred to as changing-look (CL) AGNs.

At a redshift of 0.043, Markarian 1018 (or Mrk 1018 for brief) is an energetic galaxy and AGN system. It’s a post-merger remnant—the host galaxy is clearly irregular, with a tidal tail. Earlier observations of Mrk 1018 have discovered that its AGN belongs to a gaggle of extraordinarily uncommon CL-AGNs with a number of transitions.

A bunch of astronomers led by Roisín Brogan of College of Potsdam in Germany commenced in October 2019 a high-cadence optical monitoring of the AGN in Mrk 1018. The observations, carried out with STELLA telescopes on the Izana Observatory in Tenerife, Spain, caught a powerful outburst in mid-2020.

The observational marketing campaign discovered that the 2020 outburst was uneven with an increase of lower than 100 days and a decline of at the least 200 days. The astronomers famous that the best-fit perform to the decline is linear, thus this means that the outburst was not attributable to a tidal disruption occasion (TDE) as these flares are anticipated to say no with a power-law form.

Furthermore, the group analyzed X-ray and ultraviolet XMM-Newton observations taken roughly 18 months earlier than and 7 months after the noticed optical peak of the outburst. No intrinsic absorption was discovered earlier than and after the outburst, which guidelines out the situation that the noticed enhance of emission was because of a short lived lower in obscuring materials.

All in all, the outcomes counsel that the outburst almost certainly attributable to a drastic, short-term enhance of the accretion charge, for which there are a number of explanations.

“We focus on a number of situations. Disk fashions are possible too inefficient to drive the noticed speedy enhance and reduce within the AGN’s mild curves. CCA [chaotic cold accretion] can clarify the noticed short-term outburst with a number of orders of magnitude change in speedy time. Different potential interpretations may be ascribed to a BBH [binary black hole] or a rSMBH [recoiling supermassive black hole],” the authors of the paper concluded.

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