The Close AGN Reference Survey (CARS)

Mrk 1018 halts dimming and experiences strong short-term variability^⋆

¹ Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
e-mail: mkrumpe@aip.de
² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
³ Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
⁴ Yale Center for Astronomy and Astrophysics, Yale University, 52 Hillhouse Ave, New Haven, CT 06511, USA
⁵ School of Physics & Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA, UK
⁶ Gemini Observatory, Northern Operations Center, 670 N. A’ohoku Pl., Hilo, HI, 96720, USA
⁷ Max-Planck-Institut für extraterrestische Physik, Giessenbachstr. 1, 85748 Garching, Germany
⁸ I. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
⁹ LERMA, Observatoire de Paris, Collège de France, PSL, CNRS, Sorbonne Univ., UPMC, 75014 Paris, France
¹⁰ Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006, Australia
¹¹ ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Australia
¹² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
¹³ Instituto de Astrofísica de Andalucía, Glorieta de las Astronomía s/n, 18008 Granada, Spain
¹⁴ Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA

Received: 18 September 2017
Accepted: 24 October 2017

Abstract

After changing optical AGN type from 1.9 to 1 in 1984, the AGN Mrk 1018 recently reverted back to its type 1.9 state. Our ongoing monitoring now reveals that the AGN has halted its dramatic dimming, reaching a minimum around October 2016. The minimum was followed by an outburst rising with ~0.25 U-band mag/month. The rebrightening lasted at least until February 2017, as confirmed by joint Chandra and Hubble observations. Monitoring was resumed in July 2017 after the source emerged from sunblock, at which point the AGN was found only ~0.4 mag brighter than its minimum. The intermittent outburst was accompanied by the appearance of a red wing asymmetry in broad-line shape, indicative of an inhomogeneous broad-line region. The current flickering brightness of Mrk 1018 following its rapid fading either suggests that the source has reignited, remains variable at a low level, or may continue dimming over the next few years. Distinguishing between these possibilities requires continuous multiwavelength monitoring.