γ-Cascade V4: A semi-analytical code for modeling cosmological gamma-ray propagation

Since the universe is not transparent to gamma rays with energies above around one hundred GeV, it is necessary to account for the interaction of high-energy photons with intergalactic radiation fields in order to model gamma-ray propagation. Here, we present a public numerical software for the modeling of gamma-ray observables. This code computes the effects on gamma-ray spectra from the development of electromagnetic cascades and cosmological redshifting. The code introduced here is based on the original γ-Cascade, and builds on it by improving its performance at high redshifts, introducing new propagation modules, and adding many more extragalactic radiation field models, which enables the ability to estimate the uncertainties inherent to EBL modeling. We compare the results of this new code to existing Monte Carlo electromagnetic transport models, finding good agreement within EBL uncertainties.

鉴于宇宙对能量超过约一百GeV的伽马射线并不透明，因此，在模拟伽马射线传播过程中，必须考虑高能光子与星际辐射场的相互作用。在此，我们推出一套公开的数值软件，用于模拟伽马射线可观测性。该代码计算了电磁级联和宇宙红移发展对伽马射线光谱的影响。所引入的代码基于原始的γ-Cascade，并在其基础上通过优化高红移下的性能、引入新的传播模块以及增加众多河外辐射场模型，从而实现了对EBL建模固有不确定性的估算能力。我们将新代码的结果与现有的蒙特卡洛电磁输运模型进行比较，发现两者在EBL不确定性的范围内具有良好的吻合。