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AT 2018lqh and the Nature of the Emerging Population of Day-scale Duration Optical Transients

Ofek, E. O. and Adams, S. M. and Waxman, E. and Sharon, A. and Kushnir, D. and Horesh, A. and Ho, A. and Kasliwal, M. M. and Yaron, O. and Gal-Yam, A. and Kulkarni, S. R. and Bellm, E. and Masci, F. and Shupe, D. and Dekany, R. and Graham, M. and Riddle, R. and Duev, D. and Andreoni, I. and Mahabal, A. and Drake, A. (2021) AT 2018lqh and the Nature of the Emerging Population of Day-scale Duration Optical Transients. Astrophysical Journal, 922 (2). Art. No. 247. ISSN 0004-637X. doi:10.3847/1538-4357/ac24fc.

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We report on the discovery of AT 2018lqh (ZTF 18abfzgpl)—a rapidly evolving extragalactic transient in a star-forming host at 242 Mpc. The transient g-band light curve's duration above a half-maximum light is about 2.1 days, where 0.4/1.7 days are spent on the rise/decay, respectively. The estimated bolometric light curve of this object peaked at about 7 × 10⁴² erg s⁻¹—roughly 7 times brighter than the neutron star (NS)–NS merger event AT 2017gfo. We show that this event can be explained by an explosion with a fast (v ∼ 0.08 c) low-mass (≈0.07 M_⊙) ejecta, composed mostly of radioactive elements. For example, ejecta dominated by ⁵⁶Ni with a timescale of t₀ ≅ 1.6 days for the ejecta to become optically thin for γ-rays fits the data well. Such a scenario requires burning at densities that are typically found in the envelopes of neutron stars or the cores of white dwarfs. A combination of circumstellar material (CSM) interaction power at early times and shock cooling at late times is consistent with the photometric observations, but the observed spectrum of the event may pose some challenges for this scenario. We argue that the observations are not consistent with a shock breakout from a stellar envelope, while a model involving a low-mass ejecta ramming into low-mass CSM cannot explain both the early- and late-time observations.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ofek, E. O.0000-0002-6786-8774
Adams, S. M.0000-0001-5855-5939
Waxman, E.0000-0002-9038-5877
Horesh, A.0000-0002-5936-1156
Ho, A.0000-0002-9017-3567
Kasliwal, M. M.0000-0002-5619-4938
Yaron, O.0000-0002-0301-8017
Gal-Yam, A.0000-0002-3653-5598
Kulkarni, S. R.0000-0001-5390-8563
Bellm, E.0000-0001-8018-5348
Masci, F.0000-0002-8532-9395
Shupe, D.0000-0003-4401-0430
Dekany, R.0000-0002-5884-7867
Graham, M.0000-0002-3168-0139
Riddle, R.0000-0002-0387-370X
Duev, D.0000-0001-5060-8733
Andreoni, I.0000-0002-8977-1498
Mahabal, A.0000-0003-2242-0244
Alternate Title:AT2018lqh and the nature of the emerging population of day-scale duration optical transients
Additional Information:© 2021. The American Astronomical Society. Received 2021 June 29; revised 2021 September 5; accepted 2021 September 7; published 2021 December 3. E.O.O. is grateful for the support of grants from the Willner Family Leadership Institute, André Deloro Institute, Paul and Tina Gardner, Israel Science Foundation, Minerva, BSF, BSF-transformative, Weizmann-UK, and the I-CORE program of the Planning and Budgeting Committee of the Israel Science Foundation (ISF). A.G.-Y.'s research is supported by the EU via ERC grant No. 725161, the ISF GW Excellence Center, an IMOS space infrastructure grant and BSF/Transformative, Minerva and GIF grants, as well as The Benoziyo Endowment Fund for the Advancement of Science, the Deloro Institute for Advanced Research in Space and Optics, The Kimmel Center for planetary science, The Veronika A. Rabl Physics Discretionary Fund, Paul and Tina Gardner, Yeda-Sela and the WIS-CIT joint research grant; A.G.-Y. is the recipient of the Helen and Martin Kimmel Award for Innovative Investigation. Based on observations obtained with the 48 inch Samuel Oschin Telescope and 60 inch telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant No. AST-1440341 and a collaboration that includes Caltech, IPAC, Weizmann Institute of Science, Oskar Klein Center at Stockholm University, University of Maryland, University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, TANGO Consortium of Taiwan, University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW.
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
Willner Family Leadership InstituteUNSPECIFIED
Deloro Institute for Advanced Research in Space and OpticsUNSPECIFIED
Paul and Tina GardnerUNSPECIFIED
Israel Science FoundationUNSPECIFIED
Binational Science Foundation (USA-Israel)UNSPECIFIED
I-CORE Program of the Planning and Budgeting CommitteeUNSPECIFIED
European Research Council (ERC)725161
Ministry of Science (Israel)UNSPECIFIED
German-Israeli Foundation for Research and DevelopmentUNSPECIFIED
Benoziyo Endowment Fund for the Advancement of ScienceUNSPECIFIED
Kimmel Center for planetary scienceUNSPECIFIED
Veronika A. Rabl Physics Discretionary FundUNSPECIFIED
Helen and Martin Kimmel AwardUNSPECIFIED
ZTF partner institutionsUNSPECIFIED
Subject Keywords:Supernovae; Burst astrophysics; Neutron stars
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Supernovae (1668); Burst astrophysics (187); Neutron stars (1108)
Record Number:CaltechAUTHORS:20211207-393887000
Persistent URL:
Official Citation:E. O. Ofek et al 2021 ApJ 922 247
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112255
Deposited By: George Porter
Deposited On:07 Dec 2021 21:17
Last Modified:01 Feb 2022 22:58

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