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Supernova remnants (SNRs) are thought to be the primary sources of GalacticCosmic Rays (CRs). In the last few years, the wealth of gamma-ray datacollected by GeV and TeV instruments has provided important information aboutparticle energisation in these astrophysical sources, allowing us to makeprogress in assessing their role as CR accelerators. In particular, thespectrum of the gamma-ray emission detected by AGILE and Fermi-LAT from the twomiddle aged Supernova Remnants (SNRs) W44 and IC443, has been proposed as aproof of CR acceleration in SNRs. Here we discuss the possibility that theradio and gamma-ray spectra from W44 may be explained in terms ofre-acceleration and compression of Galactic CRs. The recent measurement of theinterstellar CR flux by Voyager I has been instrumental for our work, in thatthe result of the reprocessing of CRs by the shock in W44 depends on the CRspectrum at energies that are precluded to terrestrial measurement due to solarmodulation. We introduce both CR protons and helium nuclei in our calculations,and secondary electrons produced in situ are compared with the flux of GalacticCR electrons reprocessed by the slow shock of this SNR.We find that themulti-wavelength spectrum of W44 can be explained by reaccelerated particleswith no need of imposing any break on their distribution, but just a highenergy cut-off at the maximum energy the accelerator can provide.We also findthat a model including both re-acceleration and a very small fraction offreshly accelerated particles may be more satisfactory on physical grounds

The supernova remnant W44: a case of cosmic-Ray reacceleration