# Ultrahigh-energy cosmic rays from tidally-ignited white dwarfs

## TL;DR

This paper proposes a new mechanism where white dwarfs tidally compressed by intermediate-mass black holes trigger supernovae, accelerating cosmic rays to ultra-high energies, especially in dwarf galaxies and globular clusters.

## Contribution

It introduces a novel UHECR acceleration process involving white dwarf ignition by IMBHs, expanding potential astrophysical sources beyond traditional models.

## Key findings

- Tidal compression of white dwarfs by IMBHs can produce UHECRs.
- Dwarf galaxies and globular clusters are promising sites for this acceleration.
- The mechanism naturally explains the intermediate composition of observed UHECRs.

## Abstract

Ultra-high-energy cosmic rays (UHECRs) can be accelerated by tidal disruption events of stars by black holes. We suggest a novel mechanism for UHECR acceleration wherein white dwarfs (WDs) are tidally compressed by intermediate-mass black holes (IMBHs), leading to their ignition and subsequent explosion as a supernova. Cosmic rays accelerated by the supernova may receive an energy boost when crossing the accretion-powered jet. The rate of encounters between WDs and IMBHs can be relatively high, as the number of IMBHs may be substantially augmented once account is taken of their likely presence in dwarf galaxies. Here we show that this kind of tidal disruption event naturally provides an intermediate composition for the observed UHECRs, and suggest that dwarf galaxies and globular clusters are suitable sites for particle acceleration to ultra-high energies.