MrMARTIAN: A Multiresolution Mass Reconstruction Algorithm Combining Free-form and Analytic Components
Sangjun Cha, M. James Jee · The Astrophysical Journal · 2026
Abstract We present Multi-resolution MAximum-entropy Reconstruction Technique Integrating Analytic Node ( MrMARTIAN ), a new hybrid strong lensing (SL) modeling algorithm. By incorporating physically motivated analytic nodes into the free-form method MARS , MrMARTIAN enables stable and flexible mass reconstructions while mitigating oversmoothing in the inner mass profile. Its multiresolution framework increases the degrees of freedom in regions with denser SL constraints, thereby enhancing computational efficiency for a fixed number of free parameters. We evaluate the performance of MrMARTIAN using publicly available simulated SL data and find that it consistently outperforms MARS in recovering both mass and magnification. In particular, it delivers significantly more stable reconstructions when multiple images are sparsely distributed. Finally, we apply MrMARTIAN to the galaxy cluster MACS J0416.1–2403, incorporating two analytic nodes centered on the northeastern and southwestern brightest cluster galaxies. Our mass model, constrained by 412 multiple images, achieves an image-plane rms scatter of ∼ 0 . ″ 11 , the smallest to date for this dataset.