On the narrow spectral feature at $\sim$3 TeV in the MAGIC spectrum of Mrk 501

TL;DR

This paper models the narrow 3 TeV spectral feature in Mrk 501 using a time-dependent leptonic model, revealing it results from a specific electron energy distribution shaped by shock acceleration.

Contribution

It introduces a detailed time-dependent leptonic model that explains the narrow spectral feature through shock acceleration and electron energy distribution analysis.

Findings

The spectral feature is explained by a combined electron energy distribution with a power-law and pileup.

The pileup in the electron distribution is caused by shock acceleration, not stochastic processes.

The broadband SED fits observations during the 2014 flare.

Abstract

Using a time-dependent one-zone leptonic model that incorporates both shock acceleration and stochastic acceleration processes, we investigate the formation of the narrow spectral feature at $\sim3$ TeV of Mrk 501 which was observed during the X-ray and TeV flaring activity in July 2014. It is found that the broadband spectral energy distribution (SED) can be well interpreted as the synchrotron and synchrotron-self-Compton emission from the electron energy distribution (EED) that is composed by a power-law (PL) branch and a pileup branch. The PL branch produces synchrotron photons which are scattered by the electrons of the pileup branch via inverse-Compton scattering and form the narrow spectral feature observed at the TeV energies. The EED is produced by two injection episodes, and the pileup branch in EED is caused by shock acceleration rather than stochastic acceleration.