CARPP: Parametric Radiative-Transfer Fitting of Molecular Cores from Dust Continuum Data

Abstract: The density profiles of dense molecular cores are important indicators of their physical and evolutionary states. Multi-wavelength dust continuum data offers excellent constraints on the density profile of cores. Here we introduce CARPP (Core Analysis via Radiative Transfer and Profile Parameters), a publicly available fitting package that generates optimized core density and temperature profiles based on parameterized radiative transfer calculations. CARPP assumes spherical symmetry and adopts physically motivated parametric forms for the density and temperature profiles, and uses dust continuum data for fitting. Tests on synthetic data show that CARPP achieves high accuracy, namely averaged relative errors of CARPP's seven parameters being $<20\%$, when the data quality satisfies $\frac{\rm RMS \,\, noise}{[\rm peak \,\, flux]} < 0.025\times \frac{[r_0]}{\rm resolution} +0.05$, where $r_0$ is the core's characteristic radius. We select the low-mass core TMC-1C and the high-mass core Ori2-2 to demonstrate CARPP's performance on real data. It classifies TMC-1C as a Bonnor-Ebert sphere in near-hydrostatic equilibrium, while Ori2-2 exhibits a power-law-dominated profile indicative of a collapsing envelope. This capability establishes CARPP as a powerful and versatile tool to classify the dynamical states of individual cores. It offers an optimal balance between physical fidelity and computational efficiency, serving as a practical, standardized alternative to both over-simplified SED analyses and complex, time-intensive 3D radiative-transfer modeling.