We report the Fermi -LAT discovery of high-energy ( MeV/GeV ) \gamma -ray emission positionally consistent with the center of the radio galaxy M87 , at a source significance of over 10 \sigma in ten-months of all-sky survey data .
Following the detections of Cen A and Per A , this makes M87 the third radio galaxy seen with the LAT .
The faint point-like \gamma -ray source has a > 100 MeV flux of 2.45 ( \pm 0.63 ) \times 10 ^ { -8 } ph cm ^ { -2 } s ^ { -1 } ( photon index = 2.26 \pm 0.13 ) with no significant variability detected within the LAT observation .
This flux is comparable with the previous EGRET upper limit ( < 2.18 \times 10 ^ { -8 } ph cm ^ { -2 } s ^ { -1 } , 2 \sigma ) , thus there is no evidence for a significant MeV/GeV flare on decade timescales .
Contemporaneous Chandra and VLBA data indicate low activity in the unresolved X-ray and radio core relative to previous observations , suggesting M87 is in a quiescent overall level over the first year of Fermi -LAT observations .
The LAT \gamma -ray spectrum is modeled as synchrotron self-Compton ( SSC ) emission from the electron population producing the radio-to-X-ray emission in the core .
The resultant SSC spectrum extrapolates smoothly from the LAT band to the historical-minimum TeV emission .
Alternative models for the core and possible contributions from the kiloparsec-scale jet in M87 are considered , and can not be excluded .