# Lepto-Hadronic Scenarios for TeV Extensions of Gamma-Ray Burst Afterglow Spectra

**Authors:** Marc Klinger, Chengchao Yuan, Andrew M. Taylor, Walter Winter  
**arXiv:** [2403.13902](https://arxiv.org/abs/2403.13902)  
**Date:** 2024-03-20  
**Summary page:** https://www.summarizepaper.com/en/paper/2403.13902v1/

## Key points

- Recent multi-wavelength observations challenge traditional Synchrotron Self-Compton (SSC) interpretation
- Observations consistent with single power-law component spanning eight orders of magnitude in energy
- Comprehensive parameter space study conducted using AM3 software to understand behavior without additional free parameters
- Study considers radiation from non-thermal protons and lepto-hadronic cascade resulting from proton-photon interactions
- Main scenarios explored: SSC, Extended-syn, Proton-syn, pp-cascade, pγ-cascade models
- High-density environments like surrounding molecular cloud material may offer alternative explanation for flat hard spectra up to and beyond 10 TeV
- Presence of dense material could play significant role in shaping observed gamma-ray burst afterglow spectra in TeV range
- Research provides insights into complex nature of gamma-ray burst afterglows and importance of considering various physical processes and environmental factors
- Refined analysis sheds light on potential mechanisms driving observed spectral features and opens new avenues for further exploration

## Summary

Recent multi-wavelength observations of gamma-ray burst afterglows in the TeV energy range have presented a challenge to the traditional Synchrotron Self-Compton (SSC) interpretation of this emission. Instead, these observations are consistent with a single power-law component that spans over eight orders of magnitude in energy. To better understand this behavior without introducing additional free parameters, a comprehensive parameter space study was conducted using the AM3 software, which is a time-dependent, multi-messenger transport tool. This study takes into account the radiation from non-thermal protons and the lepto-hadronic cascade that occurs as a result of interactions between protons (pp) and photons (pγ). The main scenarios explored in this research include SSC, Extended-syn, Proton-syn, pp-cascade, and pγ-cascade models. By analyzing these scenarios, researchers were able to identify their respective advantages and limitations. One notable finding from this study is that high-density environments, such as those found in surrounding molecular cloud material, could offer an alternative explanation for producing flat hard spectra at energies up to and beyond 10 TeV. This suggests that the presence of dense material may play a significant role in shaping the observed gamma-ray burst afterglow spectra in the TeV energy range. Overall, this research provides valuable insights into the complex nature of gamma-ray burst afterglows and highlights the importance of considering various physical processes and environmental factors when interpreting high-energy astrophysical phenomena. The refined analysis presented here sheds light on potential mechanisms driving the observed spectral features and opens up new avenues for further exploration in understanding these energetic events.