Testing the dark matter subhalo hypothesis of the gamma-ray source 3FGL J2212.5+0703

N-body simulations predict that galaxies at the Milky Way scale host a large number of dark matter (DM) subhalos. Some of these subhalos, if they are massive enough or close enough to the Earth, might be detectable in gamma rays due to the DM annihilation. 3FGL J2212.5+0703, an unidentified gamma-ray source, has been suggested to be the counterpart candidate of a DM subhalo by Bertoni et al. In this work we analyze the Fermi-LAT Pass 8 data of 3FGL J2212.5+0703 to independently test the DM subhalo hypothesis of this source. In order to suppress the possible contamination from two nearby very bright blazars, we just take into account the front-converting gamma rays which have better angular resolutions than that of the back-converting photons. In addition to the spatial distribution analysis, we have extended the spectrum analysis down to the energies of similar to 100 MeV, and thoroughly examined the variability of the emission during the past 8 years. We confirm that 3FGL J2212.5+0703 is a steady and spatially extended gamma-ray emitter at a high confidence level. The spectrum is well consistent with that expected from DM annihilation into b (b) over bar. The introduction of a phenomenological LogParabola spectrum just improves the fit slightly. All these results suggest that 3FGL J2212.5+0703 could be indicative of a DM subhalo.