Late-time Radio Brightening and Emergence of a Radio Jet in the Changing-look AGN 1ES 1927+654
Year: 2025
Type: article
Abstract: We present multifrequency (5–345 GHz) and multiresolution radio observations of 1ES 1927+654, widely considered one of the most unusual and extreme changing-look active galactic nuclei (CL-AGNs). The source was first designated a CL-AGN after an optical outburst in late 2017 and has since displayed considerable changes in X-ray emission, including the destruction and rebuilding of the X-ray corona in 2019–2020. Radio observations prior to 2023 show a faint and compact radio source typical of a radio-quiet AGN. Starting in 2023 February, 1ES 1927+654 began exhibiting a radio flare with a steep exponential rise, reaching a peak 60 times previous flux levels, and has maintained this higher level of radio emission for over a year to date. The 5–23 GHz spectrum is broadly similar to gigahertz-peaked radio sources, which are understood to be young radio jets less than ∼1000 yr old. Recent high-resolution Very Long Baseline Array observations at 23.5 GHz now show resolved extensions on either side of the core, with a separation of ∼0.15 pc, consistent with a new and mildly relativistic bipolar outflow. A steady increase in the soft X-ray band (0.3–2 keV) concurrent with the radio may be consistent with jet-driven shocked gas, though further observations are needed to test alternate scenarios. This source joins a growing number of CL-AGNs and tidal disruption events that show late-time radio activity, years after the initial outburst.
Authors: Eileen T. Meyer, Sibasish Laha, Onic I. Shuvo, Agniva Roychowdhury, David A. Green, Lauren Rhodes, Amelia M. Hankla, Alexander Philippov, Rostom Mbarek, Ari laor, Mitchell C. Begelman, Dev R. Sadaula, Ritesh Ghosh, Gabriele Bruni, Francesca Panessa, Matteo Guainazzi, Ehud Behar, Megan Masterson, Haocheng Zhang, Xiaolong Yang, Mark A. Gurwell, Garrett K. Keating, David Williams-Baldwin, Justin D. Bray, Emmanuel K. Bempong-Manful, Nicholas Wrigley, Stefano Bianchi, Federica Ricci, Fabio La Franca, Erin Kara, Markos Georganopoulos, Samantha Oates, Matt Nicholl, Main Pal, S. Bradley Cenko
Institutions: University of Maryland, Baltimore County, Goddard Space Flight Center, Space Telescope Science Institute, University of Cambridge, University of Oxford, Joint Space Science Institute, University of Maryland, College Park, Technion – Israel Institute of Technology, National Institute of Standards and Technology, Joint Institute for Laboratory Astrophysics, University of Colorado Boulder, Institute for Space Astrophysics and Planetology, National Institute for Astrophysics, European Space Agency, European Space Research and Technology Centre, Massachusetts Institute of Technology, Shanghai Astronomical Observatory, Center for Astrophysics Harvard & Smithsonian, University of Manchester, University of Bristol, Roma Tre University, Astronomical Observatory of Rome, University of Birmingham, Queen's University Belfast, University of Delhi
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,400
Funders: National Science Foundation, Smithsonian Institution, California Institute of Technology, UK Research and Innovation, European Commission, Trinity College Dublin, Swinburne University of Technology, Academia Sinica, Stockholms Universitet, Smithsonian Astrophysical Observatory, Science and Technology Facilities Council, Deutsches Elektronen-Synchrotron, Institut National de Physique Nucléaire et de Physique des Particules
OpenAlex ID: W4406327872