Discovery of a Radiation Component from the Vela Pulsar Reaching 20 Teraelectronvolts

TL;DR

This paper reports the discovery of a new gamma-ray radiation component from the Vela pulsar extending up to 20 TeV, indicating it accelerates particles to higher energies than previously observed, challenging existing models.

Contribution

It presents the first detection of a multi-TeV gamma-ray component from the Vela pulsar, expanding understanding of pulsar acceleration mechanisms beyond current models.

Findings

Gamma-ray pulsation energies extend to at least 20 TeV.

Vela pulsar accelerates particles to Lorentz factors >4×10^7.

Challenges existing models of pulsar high-energy emission.

Abstract

Gamma-ray observations have established energetic isolated pulsars as outstanding particle accelerators and antimatter factories in the Galaxy. There is, however, no consensus regarding the acceleration mechanisms and the radiative processes at play, nor the locations where these take place. The spectra of all observed gamma-ray pulsars to date show strong cutoffs or a break above energies of a few gigaelectronvolt (GeV). Using the H.E.S.S. array of Cherenkov telescopes, we discovered a novel radiation component emerging beyond this generic GeV cutoff in the Vela pulsar's broadband spectrum. The extension of gamma-ray pulsation energies up to at least 20 teraelectronvolts (TeV) shows that Vela pulsar can accelerate particles to Lorentz factors higher than $4\times10^7$. This is an order of magnitude larger than in the case of the Crab pulsar, the only other pulsar detected in the TeV energy range. Our results challenge the state-of-the-art models for high-energy emission of pulsars while providing a new probe, i.e. the energetic multi-TeV component, for constraining the acceleration and emission processes in their extreme energy limit.