Candidate Tidal Disruption Event AT2019fdr Coincident with a High-Energy Neutrino

The origins of the high-energy cosmic neutrino flux remain largely unknown. Recently, one high-energy neutrino was associated with a tidal disruption event (TDE). Here we present AT2019fdr, an exceptionally luminous TDE candidate, coincident with another high-energy neutrino. Our observations, including a bright dust echo and soft late-time x-ray emission, further support a TDE origin of this flare. The probability of finding two such bright events by chance is just 0.034%. We evaluate several models for neutrino production and show that AT2019fdr is capable of producing the observed high-energy neutrino, reinforcing the case for TDEs as neutrino sources.

Figure 1

The bottom plot shows the light curve in the optical ZTF $g$ band, the infrared P200 Ks and WISE W1 band as well as the modeled dust echo (black line, dashdot), with the neutrino arrival time marked with a red dotted vertical line. The $SRG/\mathrm{eROSITA}$ x-ray measurements are also included. The shaded gray areas are averaged and their respective SEDs are shown in the top panels, including a fitted blue and a red blackbody (blue dashed and red dotted curve; lab frame), as well as the combined spectrum (black solid curve). The left axes all show $\nu F_{\nu }$, where $F_{\nu }$ is the spectral flux density at frequency $\nu$, while the right axes show $\nu L_{\nu }$, where $L_{\nu }$ is the luminosity at frequency $\nu$. Note: $SRG/\mathrm{eROSITA}$ data are given in units of integrated flux. The second epoch (middle plot on top) encompasses several months to include both WISE and P200 infrared data points. The global values for line-of-sight dust extinction are $A_V=0.45_{-0.14}^{+0.14}\mathrm{mag}$, assuming $R_V=3.1$ and the Calzetti attenuation law [56]. Note that the x-ray measurements were not included in the blackbody fits. The luminosities are given in the source rest frame.

Figure 2

Neutrino fluence for the three models described here. The reported energy of the neutrino event [49], represented by the dotted vertical line, should be viewed as a lower limit to the neutrino energy.