Elsa

In the last years, with the increasing number of discovered $gamma$-ray
sources, important efforts have been dedicated to establish the origin of
this high-energy emission using observations in other spectral bands. Supernova remnants (SNRs) have been proposed as possible generators of
$gamma$-rays in our Galaxy, among other astrophysical sources. SNR’s shocks are expected to be sites of cosmic ray acceleration
and clouds of dense material can provide an effective target for proton-proton collisions and subsequent production of $gamma$-rays.
We present a preliminary study of the molecular and
atomic material towards G40.5$-$0.5 and G45.7$-$0.4 (two SNRs located in
the vicinity of high-energy sources) and the TeV SNR candidate G44.5$-$0.2, to establish the origin of the $gamma$-ray emission.
In addition, the study of the interstellar medium also provides important clues on how SNRs interact with and modify their local environment.