Multi-Messenger Predictions for T Coronae Borealis: Probing Particle Acceleration in Novae

Abstract: The MAGIC detection of near-TeV gamma-rays from the 2021 outburst of the recurrent nova RS Ophiuchi (RS Oph) has established it as a TeV-scale particle accelerator. However, the underlying production mechanism --\textit{hadronic} versus \textit{leptonic}-- remains uncertain due to the non-detection of coincident neutrinos at IceCube. Indeed, the neutrino flux predicted by the hadronic model for RS Oph was below IceCube sensitivity. T Coronae Borealis (T CrB), a nova similar to RS Oph, is anticipated to undergo an outburst soon. Being closer to Earth (0.8 kpc versus 2.45 kpc for RS Oph), T CrB is expected to yield a higher neutrino flux, making the upcoming outburst a once in a lifetime opportunity to test-and potentially detect-nova neutrinos. In this work, we present the first model-based estimates of the hadronic secondary fluxes from T CrB and assess their detectability with gamma-ray (LHAASO, Fermi-LAT, MAGIC, H.E.S.S., MACE, and HERD) and neutrino (IceCube and KM3NeT) telescopes. We adopt two proton-acceleration mechanisms: (i) an external shock (ES) driven mechanism at the interaction ($10^{13}$ cm) of nova ejecta and the red giant wind, and (ii) magnetic reconnection (MR) near the white dwarf surface ($10^{9}$ cm). The latter, arising deep inside the nova system, will fully absorb gamma-rays while allowing only neutrinos to escape. This could potentially produce neutrino signals hours before the ES origin photons or neutrinos-a unique temporal delay signature. For our benchmark ES model, gamma-rays are detectable across all facilities, while the neutrino detection prospect is poor. Only a tiny upper part of the ES model parameter space is above IceCube/KM3NeT sensitivity. In contrast, both observatories have significantly better prospects for detecting neutrinos in the MR scenario.