After almost three years of data taking in sky survey mode , the Fermi -LAT has detected \gamma -ray emission toward the Tycho ’ s Supernova Remnant ( SNR ) .
The Tycho SNR is among the youngest remnants in the Galaxy , originating from a Type Ia Supernova in AD 1572 .
The \gamma -ray integral flux from 400 MeV up to 100 GeV has been measured to be ( 3.5 \pm 1.1 _ { stat } \pm 0.7 _ { syst } ) \times 10 ^ { -9 } cm ^ { -2 } s ^ { -1 } with a photon index of 2.3 \pm 0.2 _ { stat } \pm 0.1 _ { syst } .

A simple model consistent with TeV , X-ray and radio data is sufficient to explain the observed emission as originating from \pi ^ { 0 } -decays as a result of cosmic-ray acceleration and interaction with the ambient medium .