LeHaMoC: a versatile time-dependent lepto-hadronic modeling code for high-energy astrophysical sources

TL;DR

LeHaMoC is a fast, versatile, time-dependent leptohadronic modeling code designed for high-energy astrophysical sources, capable of fitting multi-messenger data and simulating neutrino and electromagnetic signals.

Contribution

It introduces a new, efficient numerical code for modeling time-dependent leptohadronic processes in astrophysical sources, with validation against existing tools and applications to real data.

Findings

Good agreement with existing code within 10-30%

Successfully fitted AGN spectral energy distribution

Simulated neutrino and electromagnetic signals from NGC 1068

Abstract

Recent associations of high-energy neutrinos with active galactic nuclei (AGN) have revived the interest in leptohadronic models of radiation from astrophysical sources. The rapid increase in the amount of acquired multi-messenger data will require soon fast numerical models that may be applied to large source samples. We develop a time-dependent leptohadronic code, LeHaMoC, that offers several notable benefits compared to other existing codes, such as versatility and speed. LeHaMoC solves the Fokker-Planck equations of photons and relativistic particles (i.e. electrons, positrons, protons, and neutrinos) produced in a homogeneous magnetized source that may also be expanding. The code utilizes a fully implicit difference scheme that allows fast computation of steady-state and dynamically evolving physical problems. We first present test cases where we compare the numerical results obtained with LeHaMoC against exact analytical solutions and numerical results computed with ATHE$\nu$A, a well-tested code of similar philosophy but different numerical implementation. We find a good agreement (within 10-30%) with the numerical results obtained with ATHE$\nu$A without evidence of systematic differences. We then demonstrate the capabilities of the code through illustrative examples. First, we fit the spectral energy distribution from a jetted AGN in the context of a synchrotron-self Compton model and a proton-synchrotron model using Bayesian inference. Second, we compute the high-energy neutrino signal and the electromagnetic cascade induced by hadronic interactions in the corona of NGC 1068. LeHaMoC is easily customized to model a variety of high-energy astrophysical sources and has the potential to become a widely utilized tool in multi-messenger astrophysics.