Sharp Rise in Cosmic Ray Irradiation of Organisms on Earth Caused by a Nearby SN Shockwave Passage

TL;DR

This study models how a nearby supernova shockwave could dramatically increase cosmic ray irradiation on Earth, potentially causing widespread biological effects and mutations, with lethal effects possible within about 18 parsecs.

Contribution

It introduces a new simulation approach considering shockwave crossing effects on cosmic ray flux, revealing higher external ionization and biosphere irradiation than previous models.

Findings

External ionization at Earth's surface can increase significantly.

Cosmogenic ${}^{14}$C decay can irradiate deep ocean organisms.

Lethal irradiation effects could occur within approximately 18 parsecs for a supernova of 10^{51} erg.

Abstract

The work considers the modelling of nearby supernova (SN) effects on Earth's biosphere via cosmic rays (CRs) accelerated by shockwaves. The rise of the radiation background on Earth resulted from the external irradiation by CR high-energy particles and internal radiation in organisms by the decay of cosmogenic ${}^{14}$C is evaluated. We have taken into account that the CR flux near Earth goes up steeply when the shockwave crosses the Solar System, while in previous works the CR transport was considered as purely diffusive. Our simulations demonstrate a high rise of the external ionization of the environments at Earth's surface by atmospheric cascade particles that penetrate the first 70-100 m of water depth. Also, the cosmogenic ${}^{14}$C decay is able to irradiate the entire biosphere and deep ocean organisms. We analyzed the probable increase in mutation rate and estimated the distance between Earth and an SN, where the lethal effects of irradiation are possible. Our simulations demonstrate that for SN energy of around $10^{51}$ erg the lethal distance could be $\sim$ 18 pc.