[Paper Review] High-energy neutrinos from the cosmic accelerator RX J1713.7-3946

J. Alvarez‐Muñiz, F. Halzen|arXiv (Cornell University)|May 23, 2002

Astrophysics and Cosmic Phenomena3 citations

TL;DR

This paper calculates that the supernova remnant RX J1713.7-3946 produces at least 40 muon-type neutrinos per kilometer-squared per year due to proton acceleration, providing a key prediction for high-energy neutrino detection. It further demonstrates how neutrino observations can confirm whether TeV gamma rays from sources like blazars and supernova remnants originate from neutral pion decay, thereby confirming their role as cosmic ray accelerators.

ABSTRACT

The observation of TeV-gamma rays of $\\pi^0$ origin from the supernova remnant RX J1713.7-3946 has revealed the first specific site where protons are accelerated to energies typical of the main component of the cosmic rays. In this letter we calculate the high-energy neutrino flux associated with this source to be at least 40 muon-type neutrinos per kilometer-squared per year. We perform the same calculations for other known sources of TeV-gamma rays and show how neutrino observations can establish whether the TeV-gamma rays emitted by blazars and supernova remnants are the decay products of neutral pions and thus unequivocally establish the sources as cosmic accelerators.

Motivation & Objective

• To predict the high-energy neutrino flux from the supernova remnant RX J1713.7-3946, a known source of TeV gamma rays.
• To establish a method for confirming whether TeV gamma rays from astrophysical sources originate from neutral pion decay.
• To demonstrate that neutrino observations can unequivocally identify cosmic accelerators by distinguishing pion decay from other emission mechanisms.
• To extend the analysis to other known TeV gamma-ray sources, such as blazars, to assess their potential as cosmic ray accelerators.

Proposed method

• Calculates the high-energy neutrino flux expected from proton-proton interactions in the cosmic ray accelerator environment of RX J1713.7-3946.
• Uses the observed TeV gamma-ray flux from π⁰ decay to infer the proton population and thus estimate the associated neutrino flux.
• Applies the same framework to other TeV gamma-ray sources, including blazars, to predict their neutrino emission levels.
• Relies on the standard hadronic model where accelerated protons interact to produce pions, which decay into gamma rays and neutrinos.
• Applies energy-dependent cross-sections and flux normalization based on observed gamma-ray spectra.
• Compares predicted neutrino fluxes with detectable thresholds to assess observability with current and future neutrino telescopes.

Experimental results

Research questions

• RQ1 What is the expected high-energy neutrino flux from the supernova remnant RX J1713.7-3946 based on its observed TeV gamma-ray emission?
• RQ2 Can neutrino observations distinguish between pion decay and alternative mechanisms for TeV gamma-ray production in cosmic accelerators?
• RQ3 To what extent can neutrino detection confirm that TeV gamma rays from sources like blazars and supernova remnants originate from neutral pion decay?
• RQ4 How do the predicted neutrino fluxes from different types of sources compare in terms of detectability?
• RQ5 What is the minimum detectable neutrino flux required to confirm the hadronic origin of TeV gamma rays?

Key findings

• The high-energy neutrino flux from RX J1713.7-3946 is predicted to be at least 40 muon-type neutrinos per kilometer-squared per year.
• This flux is a direct consequence of the observed TeV gamma rays being of π⁰ origin, confirming hadronic interactions in the source.
• The method enables a robust test of the hadronic origin of TeV gamma rays through neutrino detection.
• The same approach can be applied to other sources, such as blazars, to determine whether their gamma rays arise from pion decay.
• Neutrino observations provide a unique and unambiguous probe for identifying cosmic accelerators in the universe.
• The predicted flux is within the sensitivity range of next-generation neutrino telescopes, making it a testable prediction.