Multicollision Internal Shock Lepto-hadronic Models for Energetic Gamma-Ray Bursts (GRBs)

Abstract

For a subpopulation of energetic gamma-ray bursts (GRBs), a moderate baryonic loading may suffice to power ultra-high-energy cosmic rays (UHECRs). Motivated by this, we study the radiative signatures of cosmic-ray protons in the prompt phase of energetic GRBs. Our framework is the internal shock model with multicollision descriptions of the relativistic ejecta (with different emission regions along the jet), plus time-dependent calculations of photon and neutrino spectra. Our GRB prototypes are motivated by Fermi-Large Area Telescope-detected GRBs (including GRB 221009A) for which further, owing to the large energy flux, neutrino nonobservation of single events may pose a strong limit on the baryonic loading. We study the feedback of protons on electromagnetic spectra in synchrotron- and inverse Compton-dominated scenarios to identify the multiwavelength signatures, to constrain the maximally allowed baryonic loading, and to point out the differences between hadronic and inverse Compton signatures. We find that hadronic signatures appear as correlated flux increases in the optical-UV to soft X-ray and GeV–TeV gamma-ray ranges in the synchrotron scenarios, whereas they are difficult to identify in inverse Compton-dominated scenarios. We demonstrate that baryonic loadings around 10, which satisfy the UHECR energetic requirements, do not distort the predicted photon spectra in the Fermi Gamma-Ray Burst Monitor range and are consistent with constraints from neutrino data if the collision radii are large enough (i.e., the time variability is not too short). It therefore seems plausible that under the condition of large dissipation radii a population of energetic GRBs can be the origin of the UHECRs.

Sources of high-energy astrophysical neutrinos

“…The obtained baryonic loading 𝑓 −1 𝑒 60 is significantly lower than the one expected from the individual neutrino observations of AGN blazars. Even energy equipartition may be achievable if a special class of energetic GRBs are the sources of the UHECRs, which may also lead to interesting hadronic secondary signatures in the electromagnetic spectrum [48,49]. While for jetted AGN the neutrino peak energy and UHECR energies would be directly related (see Sec.…”

Detecting the Early Optical Flashes of Gamma-Ray Bursts with Small Telescope Arrays

“…Studying each of the classes of "non-standard" GRBs can shed light on fundamental questions in the field. For instance, while GRBs are disfavored as the primary sources of ultrahigh-energy cosmic rays and HE cosmic neutrinos, they may still contribute to these phenomena under some conditions (Senno et al 2016;Rudolph et al 2022;Rudolph et al 2023). Leading uncertainties relate to determining realistic values for the baryonic loading; the location of the dissipation region; specifics of the radiation mechanisms; the structure of relativistic jets; the dividing line between successful and failed GRBs; and the true cosmological rate of events.…”

Electromagnetic Cascade Emission from Neutrino-coincident Tidal Disruption Events

“…Compared to Winter & Lunardini (2023), where the simulations were based on the NeuCosmA (Neutrinos from Cosmic Accelerators) code (Hümmer et al 2010;Biehl et al 2018a), we change technology to self-consistently model the electromagnetic cascade in-source. We use the AM 3 (Astrophysical Modeling with Multiple Messengers) software (Gao et al 2017), which has been successfully used for lepto-hadronic models of Active Galactic Nucleus (AGN) blazars (see, e.g., Gao et al 2019;Rodrigues et al 2019Rodrigues et al , 2021 and gamma-ray bursts (Rudolph et al 2023a(Rudolph et al , 2023b, and apply it for the first time to TDEs. We address several key questions regarding EM cascade emissions in TDEs, e.g., what is the spectral shape of EM cascade emissions?…”