ﻻ يوجد ملخص باللغة العربية
We study the prompt phase of low-luminosity Gamma-Ray Bursts (LL-GRBs) as potential source of very-high-energy (VHE) gamma rays and ultra-high-energy cosmic rays (UHECRs). We model the spectral energy distribution of three representative events (with observed properties similar to GRBs 980425, 100316D and 120714B) self-consistently in a leptonic synchrotron self-Compton (SSC) scenario using the internal shock model for the relativistic outflow. To investigate the conditions under which inverse Compton radiation may lead to a peak in the GeV-TeV range potentially observable in Imaging Atmospheric Cherenkov Telescopes (IACTs), we vary the fraction of the internal energy supplying the magnetic field. Further, we determine the maximal energies achievable for UHECR nuclei and derive constraints on the baryonic loading and typical GRB duration by comparing to the extragalactic gamma-ray background. We find that LL-GRBs are potential targets for multi-wavelength studies and may be in reach of IACTs and optical/ UV instruments. For comparable sub-MeV emission and similar dynamical evolution of the outflow, the multi-wavelength predictions depend on the magnetic field: weak (strong) magnetic fields induce high (low) fluxes in the VHE regime and low (high) fluxes in the optical. VHE emission might be suppressed by $gamma gamma $-absorption close to the engine (especially for high magnetic fields) or interactions with the extragalactic background light for redshifts $z > 0.1$. For UHECRs, the maximal energies of iron nuclei (protons) can be as high as $simeq 10^{11}$-GeV ($10^{10}$-GeV) if the magnetic energy density is large (where we found a weak VHE component). These high energies are possible by decoupling the production regions of UHECR and gamma-rays in our multi-zone model. Finally, we find basic consistency with the energy budget needed to accommodate the UHECR origin from LL-GRBs.
GRB 100418A is a long burst at z=0.624 without detection of any associated supernova (SN). Its lightcurves in both the prompt and afterglow phases are similar to GRB 060614, a nearby long GRB without an associated SN. We analyze the observational dat
At low redshift, a handful of gamma-ray bursts (GRBs) have been discovered with peak luminosities ($L_{rm iso} < 10^{48.5}~rm{erg,s}^{-1}$) substantially lower than the average of the more distant ones ($L_{rm iso} > 10^{49.5}~rm{erg,s}^{-1}$). The p
The phenomenon of subpulse drifting offers unique insights into the emission geometry of pulsars, and is commonly interpreted in terms of a rotating carousel of spark events near the stellar surface. We develop a detailed geometric model for the emis
We present X-ray, UV/optical, and radio observations of the stripped-envelope, core-collapse supernova (SN) 2011ei, one of the least luminous SNe IIb or Ib observed to date. Our observations begin with a discovery within 1 day of explosion and span s
Gamma Ray Burst (GRBs) are empirically classified as long-duration GRBs (LGRBs, $>$ 2s) and short-duration GRBs (SGRBs, $<$ 2s). Physically they can be grouped into two distinct progenitor categories: those originating from collapse of massive stars