Decoding the Gravitational Geometry and Stellar Photometric Profiles of Galaxy NGC 7331

Abstract Galaxy rotation curves provide a powerful probe of mass distributions in spiral galaxies. We present a general relativistic analysis of NGC 7331 using its observed rotation curve and WISE W1 (3.4 μm) photometry to constrain the stellar mass profile. Adopting a static, spherically symmetric spacetime with anisotropic matter (vanishing radial pressure), we fit a modified exponential azimuthal velocity law to kinematic data, reconstructing metric functions and deriving enclosed mass, energy density, and tangential pressure profiles. The stellar mass underpredicts the total gravitating mass at intermediate-to-large radii, indicating dominant dark matter. The physical viability of the resulting relativistic model is examined through energy conditions, causality constraints, and the stability of circular orbits. A comparison with the standard Navarro–Frenk–White dark matter profile has been done. Overall, this study demonstrates that combining rotation-curve data with photometric stellar mass estimates within a general relativistic framework provides a consistent and physically viable description of the mass distribution in spiral galaxies such as NGC 7331.