$\gamma$-ray Emission from Classical Nova V392 Per: Measurements from Fermi and HAWC

TL;DR

This study analyzes gamma-ray emissions from the 2018 nova V392 Per using Fermi and HAWC data, revealing rapid GeV signals and setting limits on TeV emissions, advancing understanding of particle acceleration in novae.

Contribution

It provides the first combined GeV-TeV gamma-ray analysis of V392 Per, constraining TeV emission and testing hadronic acceleration models with multi-instrument data.

Findings

Detected rapid GeV gamma-ray emission with a power-law spectrum.

No significant TeV gamma-ray emission was observed, setting flux limits.

Hadronic models fit the GeV data and are constrained by HAWC observations.

Abstract

This paper reports on the $\gamma$-ray properties of the 2018 Galactic nova V392 Per, spanning photon energies $\sim$0.1 GeV to 100 TeV by combining observations from the Fermi Gamma-ray Space Telescope and the HAWC Observatory. In one of the most rapidly evolving $\gamma$-ray signals yet observed for a nova, GeV $\gamma$ rays with a power law spectrum with index $\Gamma = 2.0 \pm 0.1$ were detected over eight days following V392 Per's optical maximum. HAWC observations constrain the TeV $\gamma$-ray signal during this time and also before and after. We observe no statistically significant evidence of TeV $\gamma$-ray emission from V392 Per, but present flux limits. Tests of the extension of the Fermi/LAT spectrum to energies above 5 TeV are disfavored by 2 standard deviations (95\%) or more. We fit V392 Per's GeV $\gamma$ rays with hadronic acceleration models, incorporating optical observations, and compare the calculations with HAWC limits.