# The SNR Puppis A Revisited with Seven Years of Fermi Large Area Telescope Observations

## TL;DR

This study re-analyzes seven years of Fermi-LAT data on Puppis A, revealing gamma-ray morphology aligned with dense clouds and a spectral break at around 8 GeV, supporting a hadronic emission origin.

## Contribution

It provides a detailed gamma-ray spectral and morphological analysis of Puppis A using extended Fermi-LAT data, highlighting correlations with dense clouds and spectral features.

## Key findings

- Gamma-ray emission morphology aligns with thermal X-ray and IR emissions.
- Spectral break at approximately 8 GeV in the gamma-ray spectrum.
- Evidence supports a hadronic origin for the gamma-ray emission.

## Abstract

Puppis A is a very famous and extensively studied supernova remnant (SNR) that shows strong evidence of shock-cloud interaction. We re-analyze the GeV $\gamma$-ray emission of it using seven years Pass 8 data recorded by the Fermi Large Area Telescope (Fermi-LAT). The morphology of the $\gamma$-ray emission is more compatible with that of the thermal X-ray and IR emissions than the radio image, which suggests a possible correlation between the gamma-ray emitting region and dense clouds. The $\gamma$-ray spectrum in the energy range of 1-500 GeV shows a break at $7.92\pm1.91$ GeV with the photon indices of $1.81\pm0.08$ below the break and $2.53\pm0.12$ above the break, which can naturally explain the lack of TeV $\gamma$-ray emission from Puppis A. The multi-wavelength observations favor a hadronic origin for the $\gamma$-ray emission.