Non-Einstein source effects in massive gravity

We exhibit novel effects (absent in GR) of sources in massive gravity. First, we show that removing its ghost mode forces a field-current identity: The metric’s trace is locally proportional to that of its stress tensor; a point source implies a metric singularity enhanced by the square of the graviton’s range. Second, exterior solutions acquire spatial stress hair—their metric components depend on the interior Tij. Also, in contrast to naïve expectations, the Newtonian potential of a source is now determined by both its spatial stress and mass. Our explicit results are obtained at linear, Fierz–Pauli, level but qualitatively persist nonlinearly.