Momentum Ray Transforms, II: Range Characterization In the Schwartz space

Abstract

The momentum ray transform $I^k$ integrates a rank $m$ symmetric tensor field $f$ over lines of ${\mathbb{R}}^n$ with the weight $t^k$: $ (I^k\!f)(x,ξ)=\int_{-\infty}^\infty t^kłf(x+tξ),ξ^m\r\,dt. $ We give the range characterization for the operator $f\mapsto (I^{0}f,I^{1}f,\dots ,I^{m}f)$ on the Schwartz space of rank $m$ smooth fast decaying tensor fields. In dimensions $n\ge 3$, the range is characterized by certain differential equations of order $2(m+1)$ which generalize the classical John equations. In the two-dimensional case, the range is characterized by certain integral conditions which generalize the classical Gelfand -- Helgason -- Ludwig conditions.