Ultrahigh-energy neutrino searches using next-generation gravitational wave detectors at radio neutrino detectors: GRAND, IceCube-Gen2 Radio, and RNO-G

TL;DR

This paper evaluates the potential for next-generation gravitational wave and radio neutrino detectors to jointly identify ultrahigh-energy neutrinos from binary neutron star mergers, enhancing multimessenger astrophysics.

Contribution

It introduces a framework for GW-triggered stacking searches with radio neutrino detectors, estimating detection probabilities and constraints for joint observations.

Findings

GRAND and IceCube-Gen2 Radio can detect neutrinos if BNS mergers emit 10^{50}-10^{51} erg in UHE neutrinos.

A 99% detection probability is possible within 15 years for certain energy and beaming assumptions.

Non-detections can constrain neutrino emission parameters at 3σ level within similar timescales.

Abstract

Binary neutron star (BNS) mergers can be sources of ultrahigh-energy (UHE) cosmic rays and potential emitters of UHE neutrinos. The upcoming and current radio neutrino detectors like the Giant Radio Array for Neutrino Detection (GRAND), IceCube-Gen2 Radio, and the Radio Neutrino Observatory in Greenland (RNO-G) are projected to reach the required sensitivities to search for these neutrinos. In particular, in conjunction with the next-generation of gravitational wave (GW) detectors like Cosmic Explorer (CE) and Einstein Telescope (ET), GW-triggered stacking searches can be performed with the UHE neutrino detectors. In this work, we explore the prospects of such searches by implementing in our analysis an upper distance limit based on the sky-localization capabilities of the GW detectors from which meaningful triggers can be collected. We find that if each GW burst is associated with a total isotropic-equivalent energy of $\sim 10^{50} - 10^{51}$ erg emitted in UHE neutrinos, along with a corresponding beaming fraction of $1$%, GRAND and IceCube-Gen2 Radio have a large probability ($\sim 99$%) to detect a coincident neutrino event using the joint combination of CE+ET in a timescale of less than 15 years of operation for our fiducial choice of parameters. In case of nondetections, the parameter spaces can be constrained at $3\sigma$ level in similar timescales of operation. We also highlight and discuss the prospects of such joint radio neutrino detector network, their importance, and their role in facilitating synergic GW and neutrino observations in the next era of multimessenger astrophysics.