Unusual Hard X-Ray Flares Caught in NICER Monitoring of the Binary Supermassive Black Hole Candidate AT2019cuk/Tick Tock/SDSS J1430+2303
The nuclear transient AT2019cuk/Tick Tock/SDSS J1430+2303 has been suggested to harbor a supermassive black hole (SMBH) binary near coalescence. We report results from high-cadence NICER X-ray monitoring with multiple visits per day from 2022 January to August, as well as continued optical monitorin...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/acbea9 |
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| author | Megan Masterson Erin Kara Dheeraj R. Pasham Daniel J. D’Orazio Dominic J. Walton Andrew C. Fabian Matteo Lucchini Ronald A. Remillard Zaven Arzoumanian Otabek Burkhonov Hyeonho Choi Shuhrat A. Ehgamberdiev Elizabeth C. Ferrara Muryel Guolo Myungshin Im Yonggi Kim Davron O. Mirzaqulov Gregory S. H. Paek Hyun-Il Sung Joh-Na Yoon |
| author_facet | Megan Masterson Erin Kara Dheeraj R. Pasham Daniel J. D’Orazio Dominic J. Walton Andrew C. Fabian Matteo Lucchini Ronald A. Remillard Zaven Arzoumanian Otabek Burkhonov Hyeonho Choi Shuhrat A. Ehgamberdiev Elizabeth C. Ferrara Muryel Guolo Myungshin Im Yonggi Kim Davron O. Mirzaqulov Gregory S. H. Paek Hyun-Il Sung Joh-Na Yoon |
| author_sort | Megan Masterson |
| collection | DOAJ |
| description | The nuclear transient AT2019cuk/Tick Tock/SDSS J1430+2303 has been suggested to harbor a supermassive black hole (SMBH) binary near coalescence. We report results from high-cadence NICER X-ray monitoring with multiple visits per day from 2022 January to August, as well as continued optical monitoring during the same time period. We find no evidence of periodic/quasiperiodic modulation in the X-ray, UV, or optical bands; however, we do observe exotic hard X-ray variability that is unusual for typical active galactic nuclei (AGN). The most striking feature of the NICER light curve is repetitive hard (2–4 keV) X-ray flares that result in distinctly harder X-ray spectra compared to the nonflaring data. In its nonflaring state, AT2019cuk looks like a relatively standard AGN, but it presents the first case of day-long, hard X-ray flares in a changing-look AGN. We consider a few different models for the driving mechanism of these hard X-ray flares, including (1) corona/jet variability driven by increased magnetic activity, (2) variable obscuration, and (3) self-lensing from the potential secondary SMBH. We prefer the variable corona model, as the obscuration model requires rather contrived timescales and the self-lensing model is difficult to reconcile with a lack of clear periodicity in the flares. These findings illustrate how important high-cadence X-ray monitoring is to our understanding of the rapid variability of the X-ray corona and necessitate further high-cadence, multiwavelength monitoring of changing-look AGN like AT2019cuk to probe the corona-jet connection. |
| first_indexed | 2024-03-12T04:44:30Z |
| format | Article |
| id | doaj.art-f23a2a84a71241c09800a90625f5cf17 |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T04:44:30Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal Letters |
| spelling | doaj.art-f23a2a84a71241c09800a90625f5cf172023-09-03T09:30:36ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019452L3410.3847/2041-8213/acbea9Unusual Hard X-Ray Flares Caught in NICER Monitoring of the Binary Supermassive Black Hole Candidate AT2019cuk/Tick Tock/SDSS J1430+2303Megan Masterson0https://orcid.org/0000-0003-4127-0739Erin Kara1https://orcid.org/0000-0003-0172-0854Dheeraj R. Pasham2https://orcid.org/0000-0003-1386-7861Daniel J. D’Orazio3https://orcid.org/0000-0002-1271-6247Dominic J. Walton4https://orcid.org/0000-0001-5819-3552Andrew C. Fabian5https://orcid.org/0000-0002-9378-4072Matteo Lucchini6https://orcid.org/0000-0002-2235-3347Ronald A. Remillard7https://orcid.org/0000-0003-4815-0481Zaven Arzoumanian8Otabek Burkhonov9https://orcid.org/0000-0003-1169-6763Hyeonho Choi10https://orcid.org/0000-0003-4422-6426Shuhrat A. Ehgamberdiev11https://orcid.org/0000-0001-9730-3769Elizabeth C. Ferrara12https://orcid.org/0000-0001-7828-7708Muryel Guolo13https://orcid.org/0000-0002-5063-0751Myungshin Im14https://orcid.org/0000-0002-8537-6714Yonggi Kim15https://orcid.org/0000-0002-9532-1653Davron O. Mirzaqulov16https://orcid.org/0000-0003-0570-6531Gregory S. H. Paek17https://orcid.org/0000-0002-6639-6533Hyun-Il Sung18https://orcid.org/0000-0001-9515-3584Joh-Na Yoon19MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA ; mmasters@mit.eduMIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA ; mmasters@mit.eduMIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA ; mmasters@mit.eduNiels Bohr International Academy, Niels Bohr Institute , Blegdamsvej 17, DK-2100 Copenhagen, DenmarkInstitute of Astronomy, University of Cambridge , Madingley Road, Cambridge CB3 0HA, UK; Centre for Astrophysics Research, University of Hertfordshire , College Lane, Hatfield AL10 9AB, UKInstitute of Astronomy, University of Cambridge , Madingley Road, Cambridge CB3 0HA, UKMIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA ; mmasters@mit.eduMIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA ; mmasters@mit.eduX-Ray Astrophysics Laboratory, NASA Goddard Space Flight Center , Code 662, Greenbelt, Maryland 20771, USAUlugh Beg Astronomical Institute , Astronomy Street 33, Tashkent 100052, UzbekistanSNU Astronomy Research Center, Astronomy Program, Department of Physics and Astronomy, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic Of KoreaUlugh Beg Astronomical Institute , Astronomy Street 33, Tashkent 100052, Uzbekistan; National University of Uzbekistan , Tashkent 100174, UzbekistanDepartment of Astronomy, University of Maryland , College Park, MD 20742, USA; Center for Exploration and Space Studies (CRESST) , NASA/GSFC, Greenbelt, MD 20771, USA; NASA Goddard Space Flight Center , Greenbelt, MD 20771, USADepartment of Physics and Astronomy, Johns Hopkins University , 400 N. Charles Street, Baltimore, MD 21218, USASNU Astronomy Research Center, Astronomy Program, Department of Physics and Astronomy, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic Of KoreaDepartment of Astronomy and Space Science, Chungbuk National University Observatory , Chungdae-ro 1, Seowon-Gu, Cheongju, Chungbuk 28644, Republic Of KoreaUlugh Beg Astronomical Institute , Astronomy Street 33, Tashkent 100052, UzbekistanSNU Astronomy Research Center, Astronomy Program, Department of Physics and Astronomy, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic Of KoreaKorea Astronomy and Space Science Institute , 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic Of KoreaDepartment of Astronomy and Space Science, Chungbuk National University Observatory , Chungdae-ro 1, Seowon-Gu, Cheongju, Chungbuk 28644, Republic Of KoreaThe nuclear transient AT2019cuk/Tick Tock/SDSS J1430+2303 has been suggested to harbor a supermassive black hole (SMBH) binary near coalescence. We report results from high-cadence NICER X-ray monitoring with multiple visits per day from 2022 January to August, as well as continued optical monitoring during the same time period. We find no evidence of periodic/quasiperiodic modulation in the X-ray, UV, or optical bands; however, we do observe exotic hard X-ray variability that is unusual for typical active galactic nuclei (AGN). The most striking feature of the NICER light curve is repetitive hard (2–4 keV) X-ray flares that result in distinctly harder X-ray spectra compared to the nonflaring data. In its nonflaring state, AT2019cuk looks like a relatively standard AGN, but it presents the first case of day-long, hard X-ray flares in a changing-look AGN. We consider a few different models for the driving mechanism of these hard X-ray flares, including (1) corona/jet variability driven by increased magnetic activity, (2) variable obscuration, and (3) self-lensing from the potential secondary SMBH. We prefer the variable corona model, as the obscuration model requires rather contrived timescales and the self-lensing model is difficult to reconcile with a lack of clear periodicity in the flares. These findings illustrate how important high-cadence X-ray monitoring is to our understanding of the rapid variability of the X-ray corona and necessitate further high-cadence, multiwavelength monitoring of changing-look AGN like AT2019cuk to probe the corona-jet connection.https://doi.org/10.3847/2041-8213/acbea9Active galactic nucleiHigh energy astrophysicsSupermassive black holesX-ray transient sources |
| spellingShingle | Megan Masterson Erin Kara Dheeraj R. Pasham Daniel J. D’Orazio Dominic J. Walton Andrew C. Fabian Matteo Lucchini Ronald A. Remillard Zaven Arzoumanian Otabek Burkhonov Hyeonho Choi Shuhrat A. Ehgamberdiev Elizabeth C. Ferrara Muryel Guolo Myungshin Im Yonggi Kim Davron O. Mirzaqulov Gregory S. H. Paek Hyun-Il Sung Joh-Na Yoon Unusual Hard X-Ray Flares Caught in NICER Monitoring of the Binary Supermassive Black Hole Candidate AT2019cuk/Tick Tock/SDSS J1430+2303 The Astrophysical Journal Letters Active galactic nuclei High energy astrophysics Supermassive black holes X-ray transient sources |
| title | Unusual Hard X-Ray Flares Caught in NICER Monitoring of the Binary Supermassive Black Hole Candidate AT2019cuk/Tick Tock/SDSS J1430+2303 |
| title_full | Unusual Hard X-Ray Flares Caught in NICER Monitoring of the Binary Supermassive Black Hole Candidate AT2019cuk/Tick Tock/SDSS J1430+2303 |
| title_fullStr | Unusual Hard X-Ray Flares Caught in NICER Monitoring of the Binary Supermassive Black Hole Candidate AT2019cuk/Tick Tock/SDSS J1430+2303 |
| title_full_unstemmed | Unusual Hard X-Ray Flares Caught in NICER Monitoring of the Binary Supermassive Black Hole Candidate AT2019cuk/Tick Tock/SDSS J1430+2303 |
| title_short | Unusual Hard X-Ray Flares Caught in NICER Monitoring of the Binary Supermassive Black Hole Candidate AT2019cuk/Tick Tock/SDSS J1430+2303 |
| title_sort | unusual hard x ray flares caught in nicer monitoring of the binary supermassive black hole candidate at2019cuk tick tock sdss j1430 2303 |
| topic | Active galactic nuclei High energy astrophysics Supermassive black holes X-ray transient sources |
| url | https://doi.org/10.3847/2041-8213/acbea9 |
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