SIMBAD references

We searched for the γ-ray signal from M33, one of the largest galaxies in the Local Group, using the Pass8 data from the Fermi Large Area Telescope (LAT). No statistically significant γ-ray emission has been detected in the direction of M33, and we report a new upper limit of the high-energy ( > 100 MeV) photon flux of 2.3 x 10^- 9^ ph cm^- 2^ s^- 1^, which is stricter than previous constraints and implies a cosmic ray density for M33 that is lower than that suggested previously. The current limit is still, however, in agreement with the correlation of star formation rate and γ-ray luminosity inferred from the Local group galaxies and a few nearby starburst galaxies.