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arxiv: 2512.22338 · v2 · submitted 2025-12-26 · 🌌 astro-ph.HE · astro-ph.GA· hep-ph

High-energy Neutrino Predictions for T Coronae Borealis: Probing Particle Acceleration in Novae

Prantik Sarmah , Sovan Chakraborty , Xilu Wang This is my paper

Pith reviewed 2026-05-16 19:04 UTC · model grok-4.3

classification 🌌 astro-ph.HE astro-ph.GAhep-ph
keywords high-energy neutrinosrecurrent novaeT Coronae Borealismagnetic reconnectionexternal shockIceCubeKM3NeT
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The pith

Magnetic reconnection near the white dwarf in T Coronae Borealis produces detectable neutrinos that arrive hours before external shock signals.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper calculates the high-energy neutrino output expected from the next outburst of the recurrent nova T Coronae Borealis, which lies only 0.887 kpc away. It contrasts two proton-acceleration sites: an external shock at roughly 10^13 cm and magnetic reconnection at roughly 10^9 cm. Only the reconnection case yields a neutrino flux high enough for IceCube and KM3NeT to register. Because the dense reconnection environment absorbs the accompanying gamma rays, the neutrinos escape promptly and reach Earth hours ahead of any external-shock emission. The resulting time offset supplies a direct observational test that can distinguish which acceleration mechanism operates in novae.

Core claim

The magnetic reconnection scenario generates a robust neutrino flux within the reach of IceCube and KM3NeT. As the MR-produced gamma-rays are absorbed, the escaping MR neutrinos will arrive hours before any ES-origin signals. This distinct temporal separation can create a powerful phenomenological signature to disentangle the nova acceleration physics.

What carries the argument

Comparison of external-shock acceleration at 10^13 cm versus magnetic reconnection at 10^9 cm, which fixes both the absolute neutrino luminosity and the gamma-ray absorption optical depth.

If this is right

  • IceCube and KM3NeT should register neutrinos only if magnetic reconnection operates near the white dwarf.
  • Gamma-ray telescopes will see the external-shock component, but its neutrinos will be too faint to detect.
  • The hours-long lead time of MR neutrinos supplies an unambiguous temporal tag separating the two mechanisms.
  • Non-detection of early neutrinos would favor the external-shock picture for this system.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same early-neutrino signature could be searched for in other recurrent novae to map their acceleration radii.
  • A confirmed early signal would imply that particle acceleration occurs in the densest, innermost zones of the ejecta.
  • Future multi-messenger campaigns could use the time offset to constrain the magnetic-field strength and reconnection rate at the white-dwarf surface.

Load-bearing premise

The proton acceleration efficiency and the precise radial locations of the two acceleration regions are taken as given without independent measurement for T CrB.

What would settle it

Absence of any early neutrino signal before the expected gamma-ray arrival time, or a non-detection of neutrinos at the predicted MR flux level during the T CrB outburst, would falsify the magnetic-reconnection prediction.

read the original abstract

The MAGIC detection of near-TeV gamma rays from the 2021 RS Oph ($2.45$ kpc) outburst has established recurrent novae as TeV particle accelerators. However, the origin of this emission (hadronic vs leptonic) remains unclear due to the lack of coincident neutrinos detected by IceCube. The upcoming outburst of the much closer T Coronae Borealis (T CrB, $\sim0.887$ kpc) offers a unique opportunity to detect these rare nova neutrinos. Here we present the first comparative analysis of the hadronic secondary fluxes expected from the upcoming T CrB outburst and evaluate their detectability across major observatories, considering two proton-acceleration mechanisms: (i) an external shock (ES) at $\sim10^{13}$ cm, and (ii) magnetic reconnection (MR), near the white dwarf surface at $\sim10^{9}$ cm. While the benchmark ES model predicts a gamma-ray flux detectable by current facilities, its corresponding neutrino flux largely remains undetectable. In contrast, the MR scenario generates a robust neutrino flux within the reach of IceCube and KM3NeT. Importantly, as the MR-produced gamma-rays are absorbed, the escaping MR neutrinos will arrive hours before any ES-origin signals. This distinct temporal separation can create a powerful phenomenological signature to disentangle the nova acceleration physics.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The manuscript forecasts high-energy neutrino emission from the anticipated outburst of the recurrent nova T Coronae Borealis using two hadronic acceleration scenarios: an external shock (ES) at ~10^{13} cm and magnetic reconnection (MR) at ~10^9 cm. It concludes that the MR model predicts a neutrino flux detectable by IceCube and KM3NeT, with associated gamma rays being absorbed, resulting in neutrinos arriving hours earlier than potential ES signals, offering a means to probe the acceleration mechanism.

Significance. Should the MR predictions prove accurate, the work would provide a valuable multi-messenger prediction for an imminent astrophysical event, potentially leading to the first neutrino detection from a nova and insights into particle acceleration in these systems. The emphasis on temporal separation is a distinctive feature.

major comments (3)
  1. [Abstract and §3] Abstract and §3 (model setup): The proton acceleration efficiency is normalized to the RS Oph 2021 gamma-ray detection but no explicit numerical value, range, or sensitivity study is provided; this parameter directly sets the absolute neutrino flux normalization in both ES and MR cases and determines whether the MR flux reaches IceCube/KM3NeT detectability.
  2. [§4] §4 (results and detectability): The MR acceleration region is fixed at exactly 10^9 cm without T CrB-specific justification or exploration of plausible radial variations; this choice controls the target density, gamma-ray optical depth, and the claimed hours-earlier neutrino arrival, yet no optical-depth calculation or robustness test against radius shifts is shown.
  3. [§4.2] §4.2 (flux predictions): No quantitative event-rate estimates, Poisson statistics, or comparison against existing IceCube non-detections from RS Oph are reported for the MR scenario, leaving the 'robust' and 'within reach' claims without a clear statistical threshold.
minor comments (2)
  1. Add a summary table listing the adopted parameter values (efficiency, radii, densities) for both models to improve reproducibility.
  2. [§5] Clarify the precise definition of 'hours before' in the temporal separation claim by specifying the assumed outburst light-curve rise time and propagation delays.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the thoughtful and constructive report. We have revised the manuscript to address each major comment with additional details, calculations, and clarifications. Below we respond point by point.

read point-by-point responses

  1. Referee: [Abstract and §3] Abstract and §3 (model setup): The proton acceleration efficiency is normalized to the RS Oph 2021 gamma-ray detection but no explicit numerical value, range, or sensitivity study is provided; this parameter directly sets the absolute neutrino flux normalization in both ES and MR cases and determines whether the MR flux reaches IceCube/KM3NeT detectability.

    Authors: We agree that an explicit value and sensitivity analysis improve transparency. The efficiency was fixed by requiring the model to reproduce the MAGIC-observed gamma-ray luminosity of RS Oph 2021. In the revised manuscript we now state this numerical value explicitly in §3 and add a short sensitivity study showing how the predicted neutrino flux scales with the efficiency parameter. The study confirms that the MR scenario yields a detectable signal for the range of efficiencies consistent with the RS Oph data. revision: yes

  2. Referee: [§4] §4 (results and detectability): The MR acceleration region is fixed at exactly 10^9 cm without T CrB-specific justification or exploration of plausible radial variations; this choice controls the target density, gamma-ray optical depth, and the claimed hours-earlier neutrino arrival, yet no optical-depth calculation or robustness test against radius shifts is shown.

    Authors: The 10^9 cm scale is set by the white-dwarf radius and the region where magnetic reconnection is expected to operate in the strong post-outburst magnetic field. We have added an explicit gamma-ray optical-depth calculation at this radius (showing strong absorption) and a robustness test exploring radii between 5×10^8 cm and 2×10^9 cm. The test demonstrates that both the neutrino detectability and the hours-earlier arrival relative to the external-shock signal remain robust across this interval. revision: yes

  3. Referee: [§4.2] §4.2 (flux predictions): No quantitative event-rate estimates, Poisson statistics, or comparison against existing IceCube non-detections from RS Oph are reported for the MR scenario, leaving the 'robust' and 'within reach' claims without a clear statistical threshold.

    Authors: We accept that quantitative detection prospects strengthen the claims. The revised §4.2 now includes expected event rates for IceCube and KM3NeT, together with Poisson-based estimates of the probability of obtaining a significant detection. We also compare directly with the RS Oph non-detection, noting that the factor of approximately eight smaller distance to T CrB increases the expected flux by a factor of ~64, placing the MR signal comfortably above the threshold that was not reached for RS Oph. revision: yes

Circularity Check

0 steps flagged

No significant circularity: forward predictions rely on external calibration and explicit assumptions

full rationale

The paper's derivation chain models hadronic secondary production for two acceleration scenarios (ES at 10^13 cm and MR at 10^9 cm) using standard particle physics and radiative transfer. Parameters such as proton acceleration efficiency are stated as assumptions benchmarked against the independent MAGIC RS Oph detection, not fitted to T CrB data. Neutrino flux predictions and the claimed temporal lead are outputs of these models applied to T CrB's distance and outburst properties; they do not reduce by construction to the inputs or to any self-citation. The central claims remain testable by future IceCube/KM3NeT observations and are not equivalent to the calibration data.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

The predictions rest on standard astrophysical assumptions about particle acceleration in novae calibrated to the 2021 RS Oph event; no new particles or forces are introduced.

free parameters (2)
  • proton acceleration efficiency
    Efficiency parameter that sets the fraction of shock or reconnection energy going into protons; value implicitly chosen to reproduce RS Oph gamma-ray flux.
  • acceleration region radius
    Fixed at 10^13 cm for external shock and 10^9 cm for magnetic reconnection; directly controls neutrino production volume and gamma-ray absorption.
axioms (2)
  • domain assumption Gamma-ray emission from RS Oph is hadronic in origin
    Used to normalize the proton spectrum for both T CrB scenarios.
  • standard math Standard pp and p-gamma interaction cross sections and secondary yields
    Background physics for calculating neutrino and gamma-ray fluxes.

pith-pipeline@v0.9.0 · 5556 in / 1484 out tokens · 41357 ms · 2026-05-16T19:04:47.333139+00:00 · methodology

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