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NASA’s Swift Tracks Potential Magnetic Flip of Monster Black Hole

Presentation #100.28 in the session AGN.

Published onJul 01, 2023
NASA’s Swift Tracks Potential Magnetic Flip of Monster Black Hole

1ES~1927+654 is a unique changing look active galactic nucleus (CL-AGN) which recently brightened by 4 magnitudes in the optical/UV over only 3 months in 2017-2018. Shortly afterward strong broad Hα and Hβ emission lines appeared on top of the blue continuum. While the UV-optical continuum was still bright (~12 times its pre-flare state) the coronal emission (>2 keV) completely vanished for straight 3 months (Aug-Oct 2018) and then again resurfaced to 10 times its original brightness in a matter of a few months. No other AGN has ever exhibited this behavior before. In this work (Laha et al. 2022) we report the evolution of the radio, optical, UV and X-rays from the pre-flare state through mid-2021 with new and archival data from the Neil Gehrels Swift Observatory, XMM-Newton, Very Long Baseline Array, the Very Large Array, Gran Telescopio Canaris, and Galileo National Telescope. The main results from our work are: 1) The source has returned to its pre-flare state in optical, UV, and X-ray; the disk-corona relation has been re-established. 2) The X-rays vanished for 3 months and then again resurfaced, while the UV luminosity from the accretion disk continued to fall monotonically as a power law t-0.91. This slope is shallower compared to tidal disruption events t-5/3. We conjecture that a magnetic flux inversion event is the cause for this enigmatic event. 3)There is no correlation between the UV and X-rays at any time during the changing look phase. 4). The compact radio emission at spatial scales <1pc was at its lowest level during the changing look event in 2018, contemporaneous with the vanishing of the power law component, indicating that the core radio emission from the source originated from the corona. Our work resulted in a NASA press release on 5th May 2022, with the following web-link:

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