GRB 230307A is one of the brightest long-duration gamma-ray bursts (GRBs) ever detected, yet its progenitor remains uncertain due to the variety of plausible astrophysical scenarios. In this work, we investigate four possible progenitors for GRB 230307A: a binary neutron star (BNS), a neutron-star/white-dwarf (NS-WD) system, a neutron-star/black-hole merger, and a tidal disruption event involving a white dwarf and a supermassive black hole. Additionally, we explore three distinct central engine models powering the kilonova associated with the BNS: radioactive decay of $r$-process nuclei in a two-component ejecta model, a magnetar-driven model including magnetic dipole spin down, and a combined model of magnetar spin down with ${}^{56}\mathrm{Ni}$ radioactive decay. We perform Bayesian multiwavelength light curve analyses using physically motivated models and priors and evaluate model performance through Bayes factors and leave-one-out cross-validation scores. Our results show a statistical preference for a BNS or NS-WD progenitor producing a kilonova powered by a magnetar and ${}^{56}\mathrm{Ni}$ decay, characterized by a ${}^{56}\mathrm{Ni}$ mass of $\sim 4\times {10}^{-4}{M}_{\odot }$ and an ejecta mass of $0.06M_{\odot }$. Furthermore, under the assumption of a BNS origin within this model, we infer binary component masses of $m_1=1.32_{-0.06}^{+0.05}{M}_{\odot }$ and $m_2=1.24_{-0.04}^{+0.02}{M}_{\odot }$, with a dimensionless tidal deformability of $\tilde{\mathrm{\Lambda }}=437_{-265}^{+251}$. From the component mass posteriors, we infer that the observed offset can be explained by a natal kick as long as the systemic velocity is nearly aligned with the prekick orbital motion. In this case, the required kick velocity (comoving frame) and binary separation range within $v_{\mathrm{k}}^{\prime }\sim 100–150\mathrm{km}/\mathrm{s}$ and $a_0\sim 2–2.5R_{\odot }$, respectively.

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• Gamma ray bursts
• Optical, UV, & IR astronomy
• X ray astronomy
• Binary stars
• Neutron stars & pulsars