Photoelectron angular distributions (PADs) are sensitive probes of light-matter interactions beyond the dipole approximation. Using first-principles calculations, we present a complete spatial characterization of the PADs for the argon $3s$ and $3p$ subshells. Our theoretical framework systematically incorporates electric dipole ($E1$), quadrupole ($E2$), magnetic dipole ($M1$), and higher-order multipole contributions for arbitrary light polarization. The results reveal striking nondipole effects, specifically, a pronounced forward-backward asymmetry and a strong dependence on the polarization state of the incident light. Although PADs of both subshells show energy-dependent behavior across the soft x-ray regime (400 to 4000 eV), the $3p$ PADs demonstrate significantly greater variation, with nondipole contributions becoming dominant above $1000\mathrm{eV}$. These results establish argon as a fundamental benchmark for advancing photoionization theory and provide critical guidance for experiments at modern light sources, bridging the gap between theoretical predictions and experimental observables.

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• Photoemission
• Atoms
• Polarization
• Dipole approximation
• Hartree-Fock methods