We report the detection of high-energy \gamma -ray signal towards the young star-forming region , W40 .
Using 10-year Pass 8 data from the Fermi Large Area Telescope ( Fermi -LAT ) , we extracted an extended \gamma -ray excess region with a significance of \sim 18 \sigma .
The radiation has a spectrum with a photon index of 2.49 \pm 0.01 .
The spatial correlation with the ionized gas content favors the hadronic origin of the \gamma -ray emission .
The total cosmic-ray ( CR ) proton energy in the \gamma -ray production region is estimated to be the order of 10 ^ { 47 } erg .
However , this could be a small fraction of the total energy released in cosmic rays ( CRs ) by local accelerators , presumably by massive stars , over the lifetime of the system .
If so , W40 , together with earlier detections of \gamma -rays from Cygnus cocoon , Westerlund 1 , Westerlund 2 , NGC 3603 , and 30 Dor C , supports the hypothesis that young star clusters are effective CR factories .
The unique aspect of this result is that the \gamma -ray emission is detected , for the first time , from a stellar cluster itself , rather than from the surrounding ” cocoons ” .