On the Potential of Bright, Young Pulsars to Power Ultrahigh Gamma-Ray Sources

DOI: 
10.3847/2041-8213/ac66cf
Publication date: 
08/05/2022
Main author: 
de Oña Wilhelmi, Emma
IAA authors: 
López-Coto, Rubén
Authors: 
de Oña Wilhelmi, Emma;López-Coto, Rubén;Amato, Elena;Aharonian, Felix
Journal: 
The Astrophysical Journal
Refereed: 
Yes
Publication type: 
Article
Volume: 
930
Pages: 
L2
Abstract: 
The recent discovery of a new population of ultrahigh-energy gamma-ray sources with spectra extending beyond 100 TeV revealed the presence of Galactic PeVatrons-cosmic-ray factories accelerating particles to PeV energies. These sources, except for the one associated with the Crab Nebula, are not yet identified. With an extension of 1° or more, most of them contain several potential counterparts, including supernova remnants, young stellar clusters, and pulsar wind nebulae (PWNe), which can perform as PeVatrons and thus power the surrounding diffuse ultrahigh-energy gamma-ray structures. In the case of PWNe, gamma-rays are produced by electrons, accelerated at the pulsar wind termination shock, through the inverse Compton scattering of 2.7 K cosmic microwave background (CMB)radiation. The high conversion efficiency of pulsar rotational power to relativistic electrons, combined with the short cooling timescales, allow gamma-ray luminosities up to the level of ${L}_{\gamma }\sim 0.1\dot{E}$ . The pulsar spin-down luminosity, $\dot{E}$ , also determines the absolute maximum energy of individual photons: ${E}_{\gamma ,max}\approx 0.9{\dot{E}}_{36}^{0.65}\,\,{\rm{PeV}}$ . This fundamental constraint dominates over the condition set by synchrotron energy losses of electrons for young PWNe with typical magnetic field of ≍100 μG with $\dot{E}\lesssim {10}^{37}\ \mathrm{erg}\,{{\rm{s}}}^{-1}$ . We discuss the implications of E<SUB>γ</SUB> <SUB>,max</SUB> by comparing it with the highest-energy photons reported by LHAASO from a dozen of ultrahigh-energy sources. Whenever a PWN origin of the emission is possible, we use the LHAASO measurements to set upper limits on the nebular magnetic field.
Database: 
ADS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2022ApJ...930L...2D/abstract
ADS Bibcode: 
2022ApJ...930L...2D
Keywords: 
Gamma-ray sources;Pulsars;Rotation powered pulsars;Pulsar wind nebulae;High energy astrophysics;633;1306;1408;2215;739;Astrophysics - High Energy Astrophysical Phenomena