The Astrophysical Journal (Jan 2023)
A Reemerging Bright Soft X-Ray State of the Changing-look Active Galactic Nucleus 1ES 1927+654: A Multiwavelength View
- Ritesh Ghosh,
- Sibasish Laha,
- Eileen Meyer,
- Agniva Roychowdhury,
- Xiaolong Yang,
- J. A. Acosta–Pulido,
- Suvendu Rakshit,
- Shivangi Pandey,
- Josefa Becerra González,
- Ehud Behar,
- Luigi C. Gallo,
- Francesca Panessa,
- Stefano Bianchi,
- Fabio La Franca,
- Nicolas Scepi,
- Mitchell C. Begelman,
- Anna Lia Longinotti,
- Elisabeta Lusso,
- Samantha Oates,
- Matt Nicholl,
- S. Bradley Cenko,
- Brendan O’Connor,
- Erica Hammerstein,
- Jincen Jose,
- Krisztina Éva Gabányi,
- Federica Ricci,
- Sabyasachi Chattopadhyay
Affiliations
- Ritesh Ghosh
- ORCiD
- Center for Space Science and Technology, University of Maryland Baltimore County , 1000 Hilltop Circle, Baltimore, MD 21250, USA ; [email protected], [email protected]; Astrophysics Science Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Center for Research and Exploration in Space Science and Technology , NASA/GSFC, Greenbelt, MD 20771, USA
- Sibasish Laha
- ORCiD
- Center for Space Science and Technology, University of Maryland Baltimore County , 1000 Hilltop Circle, Baltimore, MD 21250, USA ; [email protected], [email protected]; Astrophysics Science Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Center for Research and Exploration in Space Science and Technology , NASA/GSFC, Greenbelt, MD 20771, USA
- Eileen Meyer
- Department of Physics, University of Maryland , Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
- Agniva Roychowdhury
- ORCiD
- Department of Physics, University of Maryland , Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
- Xiaolong Yang
- ORCiD
- Shanghai Astronomical Observatory, Chinese Academy of Sciences , Shanghai 200030, People's Republic of China; Kavli Institute for Astronomy and Astrophysics, Peking University , Beijing 100871, People's Republic of China
- J. A. Acosta–Pulido
- Instituto de Astrofísica de Canarias (IAC) , E-38200 La Laguna, Tenerife, Spain; Universidad de La Laguna (ULL) , Departamento de Astrofísica, E-38206 La Laguna, Tenerife, Spain
- Suvendu Rakshit
- ORCiD
- Aryabhatta Research Institute of Observational Sciences (ARIES) , Manora Peak, Nainital, 263002 India
- Shivangi Pandey
- Aryabhatta Research Institute of Observational Sciences (ARIES) , Manora Peak, Nainital, 263002 India
- Josefa Becerra González
- Instituto de Astrofísica de Canarias (IAC) , E-38200 La Laguna, Tenerife, Spain; Universidad de La Laguna (ULL) , Departamento de Astrofísica, E-38206 La Laguna, Tenerife, Spain
- Ehud Behar
- ORCiD
- Department of Physics , Technion, Haifa 32000, Israel
- Luigi C. Gallo
- Department of Astronomy & Physics, Saint Mary’s University , 923 Robie Street, Halifax, Nova Scotia, B3H 3C3, Canada
- Francesca Panessa
- ORCiD
- INAF—Istituto di Astrofisica e Planetologia Spaziali , via Fosso del Cavaliere 100, I-00133 Roma, Italy
- Stefano Bianchi
- ORCiD
- Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre , Via della Vasca Navale 84, I-00146, Roma, Italy
- Fabio La Franca
- ORCiD
- Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre , Via della Vasca Navale 84, I-00146, Roma, Italy
- Nicolas Scepi
- ORCiD
- School of Physics and Astronomy, University of Southampton , Highfield, Southampton, SO17 1BJ, UK
- Mitchell C. Begelman
- ORCiD
- JILA, University of Colorado and National Institute of Standards and Technology , 440 UCB, Boulder, CO 80309-0440, USA
- Anna Lia Longinotti
- ORCiD
- Instituto de Astronomía, Universidad Nacional Autónoma de México , Circuito Exterior, Ciudad Universitaria, Ciudad de México 04510, México
- Elisabeta Lusso
- ORCiD
- Dipartimento di Fisica e Astronomia, Università di Firenze , Via G. Sansone 1, I-50019, Sesto Fiorentino, Firenze, Italy; INAF—Osservatorio Astrofisico di Arcetri , Largo Enrico Fermi 5, I-50125, Firenze, Italy
- Samantha Oates
- Birmingham Institute for Gravitational Wave Astronomy and School of Physics and Astronomy, University of Birmingham , Birmingham, B15 2TT, UK
- Matt Nicholl
- ORCiD
- Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast , Belfast, BT7 1NN, UK
- S. Bradley Cenko
- ORCiD
- Astrophysics Science Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Joint Space-Science Institute, University of Maryland , College Park, MD 20742, USA
- Brendan O’Connor
- ORCiD
- Astrophysics Science Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Department of Physics, The George Washington University , Washington, DC 20052, USA; Astronomy, Physics and Statistics Institute of Sciences (APSIS), The George Washington University , Washington, DC 20052, USA; Department of Astronomy, University of Maryland , College Park, MD 20742-4111, USA
- Erica Hammerstein
- ORCiD
- Astrophysics Science Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Center for Research and Exploration in Space Science and Technology , NASA/GSFC, Greenbelt, MD 20771, USA; Department of Astronomy, University of Maryland , College Park, MD 20742-4111, USA
- Jincen Jose
- Aryabhatta Research Institute of Observational Sciences (ARIES) , Manora Peak, Nainital, 263002 India
- Krisztina Éva Gabányi
- ORCiD
- Department of Astronomy, Institute of Physics and Astronomy , ELTE Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary; Konkoly Observatory, ELKH Research Centre for Astronomy and Earth Sciences , Konkoly Thege Miklós út 15-17, H-1121 Budapest, Hungary; ELKH-ELTE Extragalactic Astrophysics Research Group, ELTE Eötvös Loránd University , Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary
- Federica Ricci
- ORCiD
- Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre , Via della Vasca Navale 84, I-00146, Roma, Italy; INAF—Osservatorio Astronomico di Roma , via Frascati 33, 00040 Monteporzio Catone, Italy
- Sabyasachi Chattopadhyay
- ORCiD
- South African Astronomical Observatory , 1 Observatory Rd, Observatory, Cape Town, 7925, South Africa
- DOI
- https://doi.org/10.3847/1538-4357/aced92
- Journal volume & issue
-
Vol. 955,
no. 1
p. 3
Abstract
1ES1927+654 is a nearby active galactic nucleus (AGN) that has shown an enigmatic outburst in optical/UV followed by X-rays, exhibiting strange variability patterns at timescales of months to years. Here we report the unusual X-ray, UV, and radio variability of the source in its postflare state (2022 January–2023 May). First, we detect an increase in the soft X-ray (0.3–2 keV) flux from 2022 May to 2023 May by almost a factor of 5, which we call the bright soft state. The hard X-ray 2–10 keV flux increased by a factor of 2, while the UV flux density did not show any significant changes (≤30%) in the same period. The integrated energy pumped into the soft and hard X-rays during this period of 11 months is ∼3.57 × 10 ^50 erg and 5.9 × 10 ^49 erg, respectively. From the energetics, it is evident that whatever is producing the soft excess (SE) is pumping out more energy than either the UV or hard X-ray source. Since the energy source presumably is ultimately the accretion of matter onto the supermassive black hole, the SE-emitting region must be receiving the majority of this energy. In addition, the source does not follow the typical disk–corona relation found in AGNs, neither in the initial flare (from 2017 to 2019) nor in the current bright soft state (2022–2023). We found that the core (<1 pc) radio emission at 5 GHz gradually increased until 2022 March, but showed a dip in 2022 August. The Güdel–Benz relation ( L _radio / L _X-ray ∼ 10 ^−5 ), however, is still within the expected range for radio-quiet AGNs, and further follow-up radio observations are currently being undertaken.
Keywords
