Justine

Supernova remnants (SNRs), pulsar wind nebulae (PWNe) and pulsars are the usual suspects to accelerate the bulk of cosmic rays in our Galaxy.
In those objects the gamma-ray emission allows us to probe the population of high-energy particles and in particular the population of accelerated hadrons radiating through the pion-decay mechanism. Those Galactic accelerators are most of the time studied as independent objects, even if, in the case of some core-collapse supernovae, the shell-like SNR, the PWN and the pulsar are in fact present in the same object.
In the case of composite SNRs, both the SNR shell and the PWN are bright enough to be observed in the same source. Understanding the nature of the gamma-ray emission in such objects can be challenging for sources of small angular extension. Previous studies of the composite SNR G326.3-1.8 (radius=0.3°) revealed bright and extended gamma-ray emission but its origin remained uncertain.
With the recent Pass8 Fermi-LAT data that provide an increased acceptance and angular resolution, we investigate the detailed morphology of this composite SNR in order to distinguish the SNR from the PWN contribution. In particular, we take advantage of the new possibility to filter events based on their angular reconstruction quality (PSF types). Disentangling the different components is crucial to clearly model the spectral properties of the source and to understand its nature.