Cosmic neutrinos provide a unique window into the otherwise hidden mechanism of particle acceleration in astrophysical objects. The IceCube Collaboration recently reported the likely association of one high-energy neutrino with a flare from the relativistic jet of an active galaxy pointed towards the Earth. However a combined analysis of many similar active galaxies revealed no excess from the broader population, leaving the vast majority of the cosmic neutrino flux unexplained. Here we present the likely association of a radio-emitting tidal disruption event, AT2019dsg, with a second high-energy neutrino. AT2019dsg was identified as part of our systematic search for optical counterparts to high-energy neutrinos with the Zwicky Transient Facility. The probability of finding any coincident radio-emitting tidal disruption event by chance is 0.5%, while the probability of finding one as bright in bolometric energy flux as AT2019dsg is 0.2%. Our electromagnetic observations can be explained through a multizone model, with radio analysis revealing a central engine, embedded in a UV photosphere, that powers an extended synchrotron-emitting outflow. This provides an ideal site for petaelectronvolt neutrino production. Assuming that the association is genuine, our observations suggest that tidal disruption events with mildly relativistic outflows contribute to the cosmic neutrino flux.
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We thank C. Lunardini, A. MacFadyen, B. Metzger, A. Mummery, A. Pizzuto, N. Stone, A. Taylor and W. Winter for discussions. We also thank the IceCube Collaboration for publishing high-energy neutrino alerts. We thank S. Digel, K. Fang, D. Horan, M. Kerr, V. Paliya and J. Racusin for feedback provided during a Fermi collaboration review. R.S. is grateful to NYU for facilitating a visit to develop this work. M.K. is grateful for the hospitality received from Columbia University and NYU during a sabbatical visit. This work was supported by the Initiative and Networking Fund of the Helmholtz Association through the Young Investigator Group programme (A.F.). S.v.V. is supported by the James Arthur Postdoctoral Fellowship. This research was partially supported by the Australian Government through the Australian Research Council’s Discovery Projects funding scheme (project DP200102471). The work of M.B. is supported through the South African Research Chair Initiative of the National Research Foundation and the Department of Science and Innovation of South Africa, under SARChI Chair grant no. 64789. Any opinion, finding and conclusion or recommendation expressed in this material is that of the authors and the NRF does not accept any liability in this regard. A.H. acknowledges support by the I-Core Program of the Planning and Budgeting Committee and the Israel Science Foundation. The UCSC transient team is supported in part by NSF grant AST-1518052, NASA/Swift grant 80NSSC19K1386, the Gordon & Betty Moore Foundation, the Heising-Simons Foundation and a fellowship from the David and Lucile Packard Foundation to R.J.F. V.Z.G. is a Moore–Sloan, WRF Innovation in Data Science and DIRAC Fellow. 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 and GIF grants, as well as the Benoziyo Endowment Fund for the Advancement of Science, the André Deloro Institute for Advanced Research in Space and Optics, 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. M.R. has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 759194-USNAC). The work of D.S. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. The work of S.R. was supported by the Helmholtz Weizmann Research School on Multimessenger Astronomy, funded through the Initiative and Networking Fund of the Helmholtz Association, DESY, the Weizmann Institute, the Humboldt University of Berlin and the University of Potsdam. This work is based on observations obtained with the Samuel Oschin telescope 48-inch and the 60-inch telescope at the Palomar Observatory as part of the ZTF project. ZTF 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 COO, IPAC and UW. SED Machine is based upon work supported by the National Science Foundation under grant no. 1106171. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. The work was supported by the GROWTH project funded by the National Science Foundation Partnership in International Research and Education program under grant no. 1545949. GROWTH is a collaborative project between the California Institute of Technology (United States), Pomona College (United States), San Diego State University (United States), Los Alamos National Laboratory (United States), University of Maryland College Park (United States), University of Wisconsin at Milwaukee (United States), Tokyo Institute of Technology (Japan), National Central University (Taiwan), Indian Institute of Astrophysics (India), Inter-University Center for Astronomy and Astrophysics (India), Weizmann Institute of Science (Israel), The Oskar Klein Centre at Stockholm University (Sweden) and Humboldt University (Germany). 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 Astrofísica de Canarias with financial support from the UK Science and Technology Facilities Council. Research at Lick Observatory is partially supported by a gift from Google. The Fermi-LAT Collaboration acknowledges support for LAT development, operation and data analysis from NASA and DOE (United States), CEA/Irfu and IN2P3/CNRS (France), ASI and INFN (Italy), MEXT, KEK and JAXA (Japan) and the K.A. Wallenberg Foundation, the Swedish Research Council and the National Space Board (Sweden). Science analysis support in the operations phase from INAF (Italy) and CNES (France) is also acknowledged. This work was performed in part under DOE contract DE-AC02-76SF00515. IceCube Neutrino Observatory is a facility of the National Science Foundation operated at the US Amundsen–Scott South Pole Station under the US Antarctic Program.
The authors declare no competing interests.
Peer review information Nature Astronomy thanks Kimitake Hayasaki and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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The public classification spectrum taken with the NTT is plotted in blue, along with later spectra from LDT, Lick, Keck and P200. Each is plotted in arbitrary units, offset for display purposes. The Balmer lines are highlighted in cyan, the HeII lines in gray, and the Bowen fluorescence lines (OIII at 3760Å, NIII at 4100Å and 4640Å) in black. Telluric lines are marked with +.
The image was taken 50 days after discovery. The green circle indicates the source region, while the red circular region was used to measure the background. The best-fit position derived from optical observations is spatially-coincident with the center of the X-ray source region.
Panel (a) shows the photon flux as a function of energy in blue, from the XMM Newton spectrum taken on 2019 May 30. The spectrum was fitted with an absorbed disk blackbody model, shown in black. Panel (b) shows the ratio of the data to the model, with the horizontal orange line indicating unity. Error bars represent 1σ intervals.
The time (Δt) is measured in the observer frame relative to MJD 58582.8, the date of discovery for AT2019dsg.
These values are inferred from the synchrotron peak flux and peak frequency (see Extended Data Fig. 4), where R is the region radius, E is the non-thermal energy, B is the magnetic field strength and ne is the density of non-thermal electrons. Except for Δt, all quantities are reported as log10 with the uncertainty (68% CL) listed in brackets.
The map shows the integrated search period G3, showing the IC191001A 90% localisation region in orange. The position of AT2019dsg is marked by a white star. The neutrino best-fit position is marked with a orange ‘ × ’. Two gamma-ray sources are significantly detected (≥ 5 σ) in the ROI but outside the neutrino uncertainty region as marked with white crosses. There is no excess consistent with the position of AT2019dsg.
The values are derived assuming a point-source with power-law index Γ=2.0 at the position of AT2019dsg, integrated over the analysis energy range 0.1-800 GeV.
The flux is derived in the 0.1-800 GeV energy range for the source during the time interval G3, with evenly spaced binning of 28 days. Vertical error bars represent 1σ intervals, horizontal bars denote bin width. 2σ upper limits are shown for bins with TS≤9. The orange dashed vertical line marks the arrival time of IC-191001A. Since this source lies outside the reported 90% error region (see Extended Data Fig. 6), and given that the LAT lightcurve shows no obvious correlation with the neutrino arrival time, we conclude that it is unlikely to be associated with the neutrino.
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Stein, R., Velzen, S.v., Kowalski, M. et al. A tidal disruption event coincident with a high-energy neutrino. Nat Astron (2021). https://doi.org/10.1038/s41550-020-01295-8