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SN 2020bqj: A Type Ibn supernova with a long-lasting peak plateau

Kool, E. C. and Karamehmetoglu, E. and Sollerman, J. and Schulze, S. and Lunnan, R. and Reynolds, T. M. and Barbarino, C. and Bellm, E. C. and De, K. and Duev, D. A. and Fremling, C. and Golkhou, V. Z. and Graham, M. L. and Green, D. A. and Horesh, A. and Kaye, S. and Kim, Y.-L. and Laher, R. R. and Masci, F. J. and Nordin, J. and Perley, D. A. and Phinney, E. S. and Porter, M. and Reiley, D. and Rodriguez, H. and van Roestel, J. and Rusholme, B. and Sharma, Y. and Sfaradi, I. and Soumagnac, M. T. and Taggart, K. and Tartaglia, L. and Williams, D. R. A. and Yan, L. (2021) SN 2020bqj: A Type Ibn supernova with a long-lasting peak plateau. Astronomy and Astrophysics, 652 . Art. No. A136. ISSN 0004-6361. doi:10.1051/0004-6361/202039137.

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Context. Type Ibn supernovae (SNe Ibn) are a rare class of stripped envelope supernovae interacting with a helium-rich circumstellar medium (CSM). The majority of the SNe Ibn reported in the literature display a surprising homogeneity in their fast-evolving lightcurves and are typically found in actively starforming spiral galaxies. Aims. We present the discovery and the study of SN 2020bqj (ZTF20aalrqbu), a SN Ibn with a long-duration peak plateau lasting 40 days and hosted by a faint low-mass galaxy. We aim to explain its peculiar properties using an extensive photometric and spectroscopic data set. Methods. We compare the photometric and spectral evolution of SN 2020bqj with regular SNe Ibn from the literature, as well as with other outliers in the SN Ibn subclass. We fit the bolometric and multi-band lightcurves with powering mechanism models such as radioactive decay and CSM interaction. We also model the host galaxy of SN 2020bqj. Results. The risetime, peak magnitude and spectral features of SN 2020bqj are consistent with those of most SNe Ibn, but the SN is a clear outlier in the subclass based on its bright, long-lasting peak plateau and the low mass of its faint host galaxy. We show through modeling that the lightcurve of SN 2020bqj can be powered predominantly by shock heating from the interaction of the SN ejecta and a dense CSM, combined with radioactive decay. The peculiar Type Ibn SN 2011hw is a close analog to SN 2020bqj in terms of lightcurve and spectral evolution, suggesting a similar progenitor and CSM scenario. In this scenario a very massive progenitor star in the transitional phase between a luminous blue variable and a compact Wolf-Rayet star undergoes core-collapse, embedded in a dense helium-rich CSM with an elevated opacity compared to normal SNe Ibn, due to the presence of residual hydrogen. This scenario is consistent with the observed properties of SN 2020bqj and the modeling results. Conclusions. SN 2020bqj is a compelling example of a transitional SN Ibn/IIn based on not only its spectral features, but also its lightcurve, host galaxy properties and the inferred progenitor properties. The strong similarity with SN 2011hw suggests this subclass may be the result of a progenitor in a stellar evolution phase that is distinct from those of progenitors of regular SNe Ibn.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Kool, E. C.0000-0002-7252-3877
Karamehmetoglu, E.0000-0001-6209-838X
Sollerman, J.0000-0003-1546-6615
Schulze, S.0000-0001-6797-1889
Lunnan, R.0000-0001-9454-4639
Barbarino, C.0000-0002-3821-6144
Bellm, E. C.0000-0001-8018-5348
De, K.0000-0002-8989-0542
Duev, D. A.0000-0001-5060-8733
Fremling, C.0000-0002-4223-103X
Golkhou, V. Z.0000-0001-8205-2506
Graham, M. L.0000-0002-9154-3136
Horesh, A.0000-0002-5936-1156
Laher, R. R.0000-0003-2451-5482
Masci, F. J.0000-0002-8532-9395
Perley, D. A.0000-0001-8472-1996
Phinney, E. S.0000-0002-9656-4032
Porter, M.0000-0003-3168-5586
van Roestel, J.0000-0002-2626-2872
Rusholme, B.0000-0001-7648-4142
Sharma, Y.0000-0003-4531-1745
Soumagnac, M. T.0000-0001-6753-1488
Taggart, K.0000-0002-5748-4558
Tartaglia, L.0000-0003-3433-1492
Williams, D. R. A.0000-0001-7361-0246
Yan, L.0000-0003-1710-9339
Additional Information:© ESO 2021. Article published by EDP Sciences. Received 10 August 2020; Accepted 26 February 2021; Published online 24 August 2021. We thank the anonymous referee for their comprehensive feedback and suggestions, which has improved this work. ECK acknowledges support from the G.R.E.A.T. research environment funded by Vetenskapsrådet, the Swedish Research Council, under project number 2016-06012, and support from The Wenner-Gren Foundations. RL is supported by a Marie Skłodowska-Curie Individual Fellowship within the Horizon 2020 European Union (EU) Framework Programme for Research and Innovation (H2020-MSCA-IF-2017-794467). ESP’s research was funded in part by the Gordon and Betty Moore Foundation through Grant GBMF5076. Y-LK has received funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (grant agreement No. 759194 USNAC). MLG acknowledges support from the DiRAC Institute in the Department of Astronomy at the University of Washington. AH is grateful for the support by grants from the Israel Science Foundation, the US-Israel Binational Science Foundation, and the I-CORE Program of the Planning and Budgeting Committee and the Israel Science Foundation. Based on observations obtained with the Samuel Oschin 48-inch Telescope and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project, a scientific collaboration among the California Institute of Technology, the Oskar Klein Centre, the Weizmann Institute of Science, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron, the University of Wisconsin-Milwaukee, and the TANGO Program of the University System of Taiwan. Further support is provided by the US National Science Foundation under Grant No. AST-1440341. This work is based in part on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. This research uses services or data provided by the Astro Data Lab at NSF’s National Optical-Infrared Astronomy Research Laboratory. NSF’s OIR Lab is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under a cooperative agreement with the National Science Foundation. The Photometric Redshifts for the Legacy Surveys (PRLS) catalog used in this paper was produced thanks to funding from the US Department of Energy Office of Science, Office of High Energy Physics via grant DE-SC0007914. The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA-CSIC) under a joint agreement with the University of Copenhagen and NOTSA. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. SED Machine is based upon work supported by the National Science Foundation under Grant No. 1106171. This work was supported by the GROWTH project funded by the National Science Foundation under Grant No. 1545949. The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant #12540303 (PI: Graham). We would like to thank participating observers on the UW APO ZTF follow-up team, including: Brigitta Spiőcz, Keaton Bell, and James Davenport. The DiRAC Institute is supported through generous gifts from the Charles and Lisa Simonyi Fund for Arts and Sciences, and the Washington Research Foundation. We thank the staff of the Mullard Radio Astronomy Observatory, University of Cambridge, for their support in the maintenance, and operation of AMI. We acknowledge support from the European Research Council under grant ERC-2012-StG-307215 LODESTONE. We thank David Kaplan and Eran Ofek for careful reading and suggestions.
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), TAPIR, Zwicky Transient Facility
Funding AgencyGrant Number
Swedish Research Council2016-06012
Wenner-Gren FoundationUNSPECIFIED
Marie Curie FellowshipH2020-MSCA-IF-2017-794467
Gordon and Betty Moore FoundationGBMF5076
European Research Council (ERC)759194
Israel Science FoundationUNSPECIFIED
Binational Science Foundation (USA-Israel)UNSPECIFIED
I-CORE Program of the Planning and Budgeting CommitteeUNSPECIFIED
ZTF partner institutionsUNSPECIFIED
Department of Energy (DOE)DE-SC0007914
Science and Technology Facilities Council (STFC)UNSPECIFIED
Heising-Simons Foundation12540303
Charles and Lisa Simonyi Fund for Arts and SciencesUNSPECIFIED
Washington Research FoundationUNSPECIFIED
European Research Council (ERC)307215
Subject Keywords:supernovae: general – supernovae: individual: SN 2020bqj – supernovae: individual: SN 2011hw
Record Number:CaltechAUTHORS:20200916-112927301
Persistent URL:
Official Citation:SN 2020bqj: A Type Ibn supernova with a long-lasting peak plateau. E. C. Kool, E. Karamehmetoglu, J. Sollerman, S. Schulze, R. Lunnan, T. M. Reynolds, C. Barbarino, E. C. Bellm, K. De, D. A. Duev, C. Fremling, V. Z. Golkhou, M. L. Graham, D. A. Green, A. Horesh, S. Kaye, Y.-L. Kim, R. R. Laher, F. J. Masci, J. Nordin, D. A. Perley, E. S. Phinney, M. Porter, D. Reiley, H. Rodriguez, J. van Roestel, B. Rusholme, Y. Sharma, I. Sfaradi, M. T. Soumagnac, K. Taggart, L. Tartaglia, D. R. A. Williams and L. Yan. A&A, 652 (2021) A136; DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105422
Deposited By: George Porter
Deposited On:17 Sep 2020 20:23
Last Modified:24 Aug 2021 21:30

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