# High-energy cosmic ray nuclei from tidal disruption events: Origin, survival, and implications

## TL;DR

This paper investigates whether tidal disruption events can produce and sustain ultrahigh-energy cosmic ray nuclei, analyzing their survival through various shock regions and implications for observed cosmic ray composition.

## Contribution

It provides a detailed analysis of UHECR nuclei survival in TDE jets and explores the viability of different stellar progenitors as sources of observed cosmic rays.

## Key findings

- UHECR nuclei can survive in external shocks and winds but are disintegrated in internal shocks.
- Main sequence star and CO white dwarf disruptions do not match UHECR observations.
- Oxygen-neon-magnesium white dwarfs could explain composition but are rare.

## Abstract

Tidal disruption events (TDEs) by supermassive or intermediate mass black holes have been suggested as candidate sources of ultrahigh-energy cosmic rays (UHECRs) and high-energy neutrinos. Motivated by the recent measurements from the Pierre Auger Observatory, which indicates a metal-rich cosmic-ray composition at ultrahigh energies, we investigate the fate of UHECR nuclei loaded in TDE jets. First, we consider the production and survival of UHECR nuclei at internal shocks, external forward and reverse shocks, and nonrelativistic winds. Based on the observations of Swift J1644+57, we show that the UHECRs can survive for external reverse and forward shocks, and disk winds. On the other hand, UHECR nuclei are significantly disintegrated in internal shocks, although they could survive for low-luminosity TDE jets. Assuming that UHECR nuclei can survive, we consider implications of different composition models of TDEs. We find that the tidal disruption of main sequence stars or carbon-oxygen white dwarfs does not successfully reproduce UHECR observations, namely the observed composition or spectrum. The observed mean depth of the shower maximum and its deviation could be explained by oxygen-neon-magnesium white dwarfs, but they may be too rare to be the sources of UHECRs.