TY - JOUR
T1 - AT 2021loi: A Bowen Fluorescence Flare with a Rebrightening Episode Occurring in a Previously Known AGN
AU - Makrygianni, Lydia
AU - Trakhtenbrot, Benny
AU - Arcavi, Iair
AU - Ricci, Claudio
AU - Lam, Marco C.
AU - Horesh, Assaf
AU - Sfaradi, Itai
AU - Bostroem, K. Azalee
AU - Hosseinzadeh, Griffin
AU - Howell, D. Andrew
AU - Pellegrino, Craig
AU - Fender, Rob
AU - Green, David A.
AU - Williams, David R.A.
AU - Bright, Joe
N1 - Funding Information:
L.M., B.T., I.A., and M.C.L. acknowledge support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreements 852097 and 950533) and from the Israel Science Foundation (grant Nos. 1849/19 and 2752/19). I.A. is a CIFAR Azrieli Global Scholar in the Gravity and the Extreme Universe Program and acknowledges support from that program, the United States–Israel Binational Science Foundation (BSF), and the Israeli Council for Higher Education Alon Fellowship. C.R. acknowledges support from Fondecyt Iniciacion grant 11190831 and ANID BASAL project FB210003. A.H. is grateful for support by the I-Core Program of the Planning and Budgeting Committee and the Israel Science Foundation and by ISF grant 647/18. A.H. is grateful for support by the Zelman Cowen Academic Initiatives. This publication was made possible through the support of an LSSTC Catalyst Fellowship to K.A.B. funded through grant 62192 from the John Templeton Foundation to LSST Corporation. The opinions expressed in this publication are those of the author(s) and do not necessarily reflect the views of LSSTC or the John Templeton Foundation.
Funding Information:
This work made use of data from the Asteroid Terrestrial- impact Last Alert System (ATLAS) project. ATLAS is primarily funded to search for near-Earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; by-products of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112, HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen's University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and the Millennium Institute of Astrophysics (MAS), Chile.
Funding Information:
Guoshoujing Telescope (the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, LAMOST) is a National Major Scientific Project built by the Chinese Academy of Sciences. Funding for the project has been provided by the National Development and Reform Commission. LAMOST is operated and managed by the National Astronomical Observatories, Chinese Academy of Sciences. The ZTF forced photometry service was funded under Heising-Simons Foundation grant No. 12540303 (PI: Graham). This work makes use of data from the Las Cumbres Observatory global telescope network. The LCO group is supported by NSF grants AST-1911151 and AST-1911225 and NASA Swift grant 80NSSC19k1639. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We acknowledge the staff who operate and run the AMI-LA telescope at Lord's Bridge, Cambridge, for the AMI-LA radio data. The AMI is supported by the Universities of Cambridge and Oxford and the European Research Council under grant ERC-2012-StG307215 LODESTONE.
Funding Information:
L.M., B.T., I.A., and M.C.L. acknowledge support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreements 852097 and 950533) and from the Israel Science Foundation (grant Nos. 1849/19 and 2752/19). I.A. is a CIFAR Azrieli Global Scholar in the Gravity and the Extreme Universe Program and acknowledges support from that program, the United States-Israel Binational Science Foundation (BSF), and the Israeli Council for Higher Education Alon Fellowship. C.R. acknowledges support from Fondecyt Iniciacion grant 11190831 and ANID BASAL project FB210003. A.H. is grateful for support by the I-Core Program of the Planning and Budgeting Committee and the Israel Science Foundation and by ISF grant 647/18. A.H. is grateful for support by the Zelman Cowen Academic Initiatives. This publication was made possible through the support of an LSSTC Catalyst Fellowship to K.A.B. funded through grant 62192 from the John Templeton Foundation to LSST Corporation. The opinions expressed in this publication are those of the author(s) and do not necessarily reflect the views of LSSTC or the John Templeton Foundation.
Funding Information:
This work also made use of the NASA/IPAC Extragalactic Database (NED), which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology, and of data, software, and web tools obtained from the High Energy Astrophysics Science Archive Research Center (HEASARC), a service of the Astrophysics Science Division at NASA/GSFC and the Smithsonian Astrophysical Observatory's High Energy Astrophysics Division.
Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/8/1
Y1 - 2023/8/1
N2 - The optical-ultraviolet transient AT 2021loi is located at the center of its host galaxy. Its spectral features identify it as a member of the Bowen fluorescence flare (BFF) class. The first member of this class was considered to be related to a tidal disruption event, but enhanced accretion onto an already active supermassive black hole was suggested as an alternative explanation. Having occurred in a previously known unobscured active galactic nucleus, AT 2021loi strengthens the latter interpretation. Its light curve is similar to those of previous BFFs, showing a rebrightening approximately 1 yr after the main peak (which was not explicitly identified but might be the case in all previous BFFs). An emission feature around 4680 Å, seen in the preflare spectrum, strengthens by a factor of ∼2 around the optical peak of the flare and is clearly seen as a double-peaked feature then, suggesting a blend of N iii λ4640 with He ii λ4686 as its origin. The appearance of O iii λ3133 and possible N iii λλ4097, 4103 (blended with Hδ) during the flare further support a Bowen fluorescence classification. Here we present ZTF, ATLAS, Keck, Las Cumbres Observatory, NEOWISE-R, Swift AMI, and Very Large Array observations of AT 2021loi, making it one of the best-observed BFFs to date. It thus provides some clarity on the nature of BFFs but also further demonstrates the diversity of nuclear transients.
AB - The optical-ultraviolet transient AT 2021loi is located at the center of its host galaxy. Its spectral features identify it as a member of the Bowen fluorescence flare (BFF) class. The first member of this class was considered to be related to a tidal disruption event, but enhanced accretion onto an already active supermassive black hole was suggested as an alternative explanation. Having occurred in a previously known unobscured active galactic nucleus, AT 2021loi strengthens the latter interpretation. Its light curve is similar to those of previous BFFs, showing a rebrightening approximately 1 yr after the main peak (which was not explicitly identified but might be the case in all previous BFFs). An emission feature around 4680 Å, seen in the preflare spectrum, strengthens by a factor of ∼2 around the optical peak of the flare and is clearly seen as a double-peaked feature then, suggesting a blend of N iii λ4640 with He ii λ4686 as its origin. The appearance of O iii λ3133 and possible N iii λλ4097, 4103 (blended with Hδ) during the flare further support a Bowen fluorescence classification. Here we present ZTF, ATLAS, Keck, Las Cumbres Observatory, NEOWISE-R, Swift AMI, and Very Large Array observations of AT 2021loi, making it one of the best-observed BFFs to date. It thus provides some clarity on the nature of BFFs but also further demonstrates the diversity of nuclear transients.
UR - http://www.scopus.com/inward/record.url?scp=85166942531&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/ace1ee
DO - 10.3847/1538-4357/ace1ee
M3 - Article
AN - SCOPUS:85166942531
SN - 0004-637X
VL - 953
SP - 1
EP - 18
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 32
ER -