Evidence for New Unidentified TeV γ-ray Sources from Angularly-Correlated Hot-Spots Observed by Independent TeV γ-ray Sky Surveys

We have examined the directional cross-correlation of statistical ‘hot-spots’ between a Northern Sky TeV Gamma Ray Survey by the Milagro Observatory and a similar survey by the Tibet Array. We find the directions of these hot-spots are angularly uncorrelated between the two surveys for large angular separations (∆θ > 4), but there appears to be a statistically significant correlation between hot-spot directions for ∆θ < 1.5. Independent simulations indicate the chance probability for the occurrence of this correlation is approximately 10, implying the existence of one or more previously unobserved TeV γ-ray sources in these directions. The data sets are consistent with both point-like sources or diffuse sources with extent of 1 − 2. Subject headings: gamma rays: observations – methods: statistical