A multi-messenger picture of galaxy mergers: Neutrinos and electromagnetic emissions

Chengchao Yuan, Kohta Murase, Peter Mészáros

Research output: Contribution to journalConference articlepeer-review

Abstract

The merger of dark matter halos and the gaseous structures embedded in them, such as galaxies and clusters of galaxies, results in strong shocks. These shocks will produce high-energy neutrinos and gamma-rays through inelastic pp collisions. In this work, we formulate the redshift dependence of the shock velocity, galactic radius, halo gas content and galactic/intergalactic magnetic fields over the dark matter halo distribution up to a redshift z = 10. We find that high-redshift mergers contribute a significant amount of the cosmic-ray (CR) luminosity density, and the resulting neutrino spectra could explain a large part of the observed diffuse neutrino flux above 0.1 PeV up to several PeV without violating the γ-ray constraint. Moreover, the secondary electrons/positrons from pion decays can produce observable emissions through synchrotron radiation and inverse Compton scattering while propagating in the host galaxies. We demonstrate that these emissions can explain the radio and X-ray fluxes of the merging galaxies such as NGC 660 and NGC 3256. In the future, with the improved sensitivity of the Cherenkov Telescope Array (CTA) and IceCube-Gen2, our model for the merging galaxies can be further tested by gamma-ray and neutrino observations.

Original languageEnglish (US)
JournalProceedings of Science
Volume358
StatePublished - 2019
Event36th International Cosmic Ray Conference, ICRC 2019 - Madison, United States
Duration: Jul 24 2019Aug 1 2019

All Science Journal Classification (ASJC) codes

  • General

Fingerprint Dive into the research topics of 'A multi-messenger picture of galaxy mergers: Neutrinos and electromagnetic emissions'. Together they form a unique fingerprint.

Cite this