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Candidate Electromagnetic Counterpart to the Binary Black Hole Merger Gravitational-Wave Event S190521g

Graham, M. J. and Ford, K. E. S. and McKernan, B. and Ross, N. P. and Stern, D. and Burdge, K. and Coughlin, M. and Djorgovski, S. G. and Drake, A. J. and Duev, D. and Kasliwal, M. and Mahabal, A. A. and van Velzen, S. and Belecki, J. and Bellm, E. C. and Burruss, R. and Cenko, S. B. and Cunningham, V. and Helou, G. and Kulkarni, S. R. and Masci, F. J. and Prince, T. and Reiley, D. and Rodriguez, H. and Rusholme, B. and Smith, R. M. and Soumagnac, M. T. (2020) Candidate Electromagnetic Counterpart to the Binary Black Hole Merger Gravitational-Wave Event S190521g. Physical Review Letters, 124 (25). Art. No. 251102. ISSN 0031-9007.

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We report the first plausible optical electromagnetic counterpart to a (candidate) binary black hole merger. Detected by the Zwicky Transient Facility, the electromagnetic flare is consistent with expectations for a kicked binary black hole merger in the accretion disk of an active galactic nucleus [B. McKernan, K. E. S. Ford, I. Bartos et al., Astrophys. J. Lett. 884, L50 (2019)] and is unlikely [< O (0.01%))] due to intrinsic variability of this source. The lack of color evolution implies that it is not a supernova and instead is strongly suggestive of a constant temperature shock. Other false-positive events, such as microlensing or a tidal disruption event, are ruled out or constrained to be < O(0.1%). If the flare is associated with S190521g, we find plausible values of total mass M_(BBH) ∼ 100 M_⊙, kick velocity v_k ∼ 200 km s⁻¹ at θ ∼ 60° in a disk with aspect ratio H/a ∼ 0.01 (i.e., disk height H at radius a) and gas density ρ ∼ 10⁻¹⁰ g cm⁻³. The merger could have occurred at a disk migration trap (a ∼ 700r_g; r_g ≡ GM_(SMBH)/c², where M_(SMBH) is the mass of the active galactic nucleus supermassive black hole). The combination of parameters implies a significant spin for at least one of the black holes in S190521g. The timing of our spectroscopy prevents useful constraints on broad-line asymmetry due to an off-center flare. We predict a repeat flare in this source due to a reencountering with the disk in ∼1.6 yr(M_SMBH)/10⁸ M_⊙)(a/10³r_g)^(3/2).

Item Type:Article
Related URLs:
URLURL TypeDescription InPhysics : Focus
Graham, M. J.0000-0002-3168-0139
McKernan, B.0000-0002-9726-0508
Ross, N. P.0000-0003-1830-6473
Stern, D.0000-0003-2686-9241
Burdge, K.0000-0002-7226-836X
Coughlin, M.0000-0002-8262-2924
Djorgovski, S. G.0000-0002-0603-3087
Duev, D.0000-0001-5060-8733
Kasliwal, M.0000-0002-5619-4938
Mahabal, A. A.0000-0003-2242-0244
van Velzen, S.0000-0002-3859-8074
Bellm, E. C.0000-0001-8018-5348
Cenko, S. B.0000-0003-1673-970X
Cunningham, V.0000-0003-2292-0441
Helou, G.0000-0003-3367-3415
Kulkarni, S. R.0000-0001-5390-8563
Masci, F. J.0000-0002-8532-9395
Prince, T.0000-0002-8850-3627
Rusholme, B.0000-0001-7648-4142
Additional Information:© 2020 American Physical Society. (Received 19 March 2020; accepted 5 June 2020; published 25 June 2020) We thank the referees for useful, timely comments that have improved this manuscript. M. J. G. is supported by NSF Grants No. AST-1518308 and AST-1815034, and NASA Grant No. 16-ADAP16-0232. K. E. S. F. and B. M. are supported by NSF Grant No. AST-1831415 and Simons Foundation Grant No. 533845. K. E. S. F. and B. M. acknowledge extremely useful conversations with Mordecai-Mark MacLow and Pierre Marchand. The work of D. S. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. M. M. K. acknowledges the GROWTH project funded by the National Science Foundation under Grant No. 1545949. M. C. is supported by NSF Grant No. PHY-2010970. 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. Z. T. F. is supported by the National Science Foundation under Grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by Caltech Optical Observatories, IPAC, and University of Washington. The ZTF forced-photometry service was funded under the Heising–Simons Foundation Grant No. 12540303 (PI: Graham). N. P. R. acknowledges support from the STFC and the Ernest Rutherford Fellowship scheme.
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), LIGO, Zwicky Transient Facility
Funding AgencyGrant Number
Simons Foundation533845
ZTF partner institutionsUNSPECIFIED
Heising-Simons Foundation12540303
Science and Technology Facilities Council (STFC)UNSPECIFIED
Issue or Number:25
Record Number:CaltechAUTHORS:20200624-144534783
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104019
Deposited By: George Porter
Deposited On:25 Jun 2020 14:35
Last Modified:25 Jun 2020 15:30

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