Title:	Ultrahigh-energy γ-Rays from Past Explosions in Our Galaxy
Authors:	Kar, Alokananda Gupta, Nayantara
Keywords:	gamma ray astronomy gamma ray sources high energy astrophysics
Issue Date:	17-Feb-2022
Publisher:	The American Astronomical Society
Citation:	The Astrophysical Journal, 2022, Vol.926, p110
Abstract:	The discovery of the sources of ultrahigh-energy photons in our Galaxy by the High-Altitude Water Cherenkov Gamma-ray Observatory and the Large High Altitude Air Shower Observatory (LHAASO) has revolutionized the field of gamma-ray astronomy in the last few years. These emissions are sometimes found in the vicinity of powerful pulsars or supernova remnants (SNRs) associated with giant molecular clouds (GMCs). Inverse Compton emission by shock-accelerated electrons emitted by pulsars and proton–proton interactions of shock-accelerated protons emitted by SNRs with cold protons in molecular clouds are often identified as the causes of these emissions. In this paper we have selected two ultrahigh-energy photon sources, LHAASO J2108+5157 and LHAASO J0341+5258, which are associated with GMCs, but no powerful pulsar or SNR has been detected in their vicinity. We have proposed a scenario where shock-accelerated electrons and protons are injected in the local environment of these sources from past explosions, which happened thousands of years ago. We show that the observed ultrahigh-energy photon flux can be explained with the secondary gamma rays produced by the time-evolved relativistic electron and proton spectra.
Description:	Open Access
URI:	http://hdl.handle.net/2289/7899
ISSN:	0004-637X 1538-4357(Online)
Alternative Location:	https://ui.adsabs.harvard.edu/abs/2022ApJ...926..110K/abstract https://arxiv.org/abs/2112.08757 https://doi.org/10.3847/1538-4357/ac4757
Copyright:	2022. The Author(s)
Appears in Collections:	Research Papers (A&A)

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