Establishing accretion flares from massive black holes as a major source of high-energy neutrinos

S. van Velzen, R. Stein, M. Gilfanov, M. Kowalski, K. Hayasaki, S. Reusch, Y. Yao, S. Garrappa, A. Franckowiak, S. Gezari, J. Nordin, C. Fremling, Y. Sharma, L. Yan, E. C. Kool, J. Sollerman, P. Medvedev, R. Sunyaev, E. Bellm, R. G. Dekany, D. A. Duev, M. J. Graham, M. M. Kasliwal, R. R. Laher, R. L. Riddle, B. Rusholme

Published 2021-11-17Version 1

High-energy neutrinos have thus far been observed in coincidence with time-variable emission from three different accreting black holes: a gamma-ray flare from a blazar (TXS 0506+056), an optical transient following a stellar tidal disruption (AT2019dsg), and an optical outburst from an active galactic nucleus (AT2019fdr). Here we present a unified explanation for the latter two of these sources: accretion flares that reach the Eddington limit. A signature of these events is a luminous infrared reverberation signal from circumnuclear dust that is heated by the flare. Using this property we construct a sample of similar sources, revealing a third event coincident with a PeV-scale neutrino. This sample of three accretion flares is correlated with high-energy neutrinos at a significance of 3.7 sigma. Super-Eddington accretion could explain the high particle acceleration efficiency of this new population.