Bjet_MCMC: A new tool to automatically fit the broadband SEDs of blazars

TL;DR

Bjet_MCMC is a newly released, user-friendly, and efficient tool that automatically fits broadband SEDs of blazars using leptonic models, aiding in physical parameter estimation from multiwavelength data.

Contribution

It introduces the first public, parallelized MCMC fitting tool for blazar broadband SEDs, incorporating leptonic models with external inverse-Compton processes.

Findings

Efficient and user-friendly MCMC fitting of blazar SEDs.

Capability to test leptonic SSC and external IC models.

Open-source code available on GitHub.

Abstract

Multiwavelength observations are now the norm for studying blazars' various states of activity, classifying them, and determining possible underlying physical processes driving their emission. Broadband emission models became unavoidable tools for testing emission scenarios and setting values to physical quantities such as the magnetic field strength, Doppler factor, or shape of the particle distribution of the emission zone(s). We announce here the first public release of a new tool, Bjet_MCMC, that can automatically fit broadband spectral energy distributions (SEDs) of blazars. The complete code is available on GitHub and allows testing leptonic synchrotron self-Compton models (SSC), with or without external inverse-Compton processes from the thermal environment of supermassive black holes (accretion disk and broad line region). The code is designed to be user-friendly and computationally efficient. It contains a core written in C++ and a fully parallelized SED fitting method. The original multi-SSC zones model of Bjet is also available on GitHub but is not included in the MCMC fitting process at the moment. We present the features, performance, and results of Bjet_MCMC, as well as user advice.