Speaker
Description
Many of the properties of Gamma Ray Bursts (GRBs) remain poorly understood, particularly for short GRBs with durations less than ~2 sec. Fermi/LAT has shown that some GRBs emit at high-energy (100 MeV - ~100 GeV) gamma-rays with a hard (index of <2) spectrum. Atmospheric Cherenkov Telescopes (IACTs) could provide information on the possible emission at very-high-energy (VHE, >100 GeV) gamma-rays. In particular MAGIC telescopes were designed to explore this particular physics case. Although no firm detection has been reported so far, the MAGIC Collaboration reported a hint of a VHE gamma-ray emissions from the short, very nearby (z=0.16) GRB 160821B. Even if it is only a hint, this creates doubts on the the standard expectations for gamma-ray emissions from GRBs: low energy (~30 GeV) over a short period (<~100 s). Moreover GRB 160821B showed a clear extended emission in the X-ray band, which can be generated by a ms pulsar after a NS-NS or NS-BH merger. In this contribution we will briefly report on the hint of the signal and on possible interpretations of the data assuming that the hint is real.
