Implications of the pulsar wind nebula scenario for a TeV gamma-ray source VER J2016+371

TL;DR

This study investigates the multiwavelength emission of the TeV gamma-ray source VER J2016+371, proposing a pulsar wind nebula origin and modeling its electron distributions to explain observations from radio to TeV energies.

Contribution

It introduces a combined electron distribution model, including Maxwellian and broken power-law components, to explain the source's emission across multiple wavelengths, challenging the hadronic scenario.

Findings

Maxwellian plus broken power-law electron distributions fit the data from radio to TeV energies.

Hadronic models require high ambient densities unsupported by observations.

A pulsar wind nebula scenario is favored based on multiwavelength morphology and spectral analysis.

Abstract

We present multiwavelength studies of a TeV gamma-ray source VER J2016+371 suggested to be associated with a supernova remnant CTB 87 (G74.9+1.2) and based on X-ray and radio morphologies, CTB 87 is identified as an evolved pulsar wind nebula. A source in the vicinity of VER J2016+371 is also detected at GeV energies by Fermi Gamma Ray Space Telescope suggesting a likely counterpart at GeV energies. We find that a broken power-law (BPL) distribution of electrons can explain the observed data at radio, X-ray and TeV energies, however, is not sufficient to explain the data at MeV--GeV energies. A Maxwellian distribution of electrons along with the BPL distribution of electrons in low magnetic fields can explain the observed multiwavelength data spanned from radio to TeV energies suggesting this as the most likely scenario for this source. We also find that although the hadronic model can explain the observed GeV--TeV data for the ambient matter density of $\sim 20~ \rm cm^{-3}$, no observational support for such high ambient density makes this hadronic scenario unlikely for this source.