Discovery of the Ultra-high energy gamma-ray Source in Deep Space

By examining the LHAASO-KM2A data of 308.33 life days, we discovered a UHE gamma-ray source, LHAASO J2108+5157. With 9.5 sigma and 8.5 sigmas, respectively, there is a significant excess of gamma-rays driven showers in both the 25–100 TeV and >100 TeV energy ranges. With an angular extension less than the point-spread function of KM2A, this source is not considerably preferred as an extended source.

A power-law function [1] with an index of -2.83 0.18stat may roughly represent the observed energy spectrum from 20 to 200 TeV. Given the flux upper limit given by Fermi-LAT data, a harsher spectrum is required at lower energies. The gamma-ray emission is linked with a massive molecular cloud, suggesting a hadronic origin.

Although no clear analogs have been discovered, more multiwavelength studies will aid in shedding fresh insights on this fascinating Ultra-high energy gamma-ray source.

[1] Power law Function

A power law is a functional connection between two numbers in statistics in which a relative change in one quantity causes a proportionate relative change in the other quantity, regardless of their original sizes: one quantity varies as a power of another.