Conveners
Exploring the Cosmos: GRB-1: Parallel-9
- Peter Veres
With the completion of the first decade of operation, Fermi-GBM has been longer in orbit than its predecessor experiment BATSE on-board CGRO. It is capable to detect almost the same number of GRBs (~240 GBM GRBs compared ~300 BATSE GRBs per year) resulting in 2357 triggers on cosmic GRBs during the first ten years. The GBM GRB catalog series is now continued by the latest releases of the GBM...
A large fraction of gamma-ray burst (GRB) spectra are very hard below the peak which indicates that the emission comes from the photosphere. The size of this fraction is investigated in two different ways. First, we use the theoretical spectrum expected from a non-dissipative flow to make synthetic Fermi/GBM spectra which are then fitted by the cut off power law function to simulate real...
Gamma-ray bursts (GRBs) detected by the Large Area Telescope (LAT) on board Fermi tend to be extraordinarily bright, making them ideal candidates for exploring emission models beyond the traditional on-axis, top-hat jet model. In this talk I will discuss our recent work modeling GRB 160625B with alternative jet structure shapes and testing assumptions typically made regarding certain physical...
We develop a model of early GRB X-ray afterglows are dominated by emission from the reverse shock propagating in highly relativistic, highly magnetized wind of a long-lasting central engine, similar to the Pulsar Wind Nebulae. The model reproduces high conversion efficiency of the wind power into radiation (fast cooling regime), afterglow plateaus, flares and abrupt intensity drops. The ...
Cosmological Gamma-Ray Bursts (GRBs) are known to arise from neutron star mergers and collapsars. We have identified 4 GRBs within 5 Mpc which are inconsistent with such an origin: they appear to be extragalactic Magnetar Giant Flares (MGFs). These are the closest known GRBs, the signals from the most distant known magnetars, and suggest a broadly morphology of MGFs than previously known. They...
Magnetars are neutron stars with the strongest-known magnetic fields in the Universe, up to a thousand times stronger than typical neutron stars. Rarely, magnetars can produce enormous eruptions, called giant flares, consisting of a highly luminous sub-second initial spike of hard X-rays and soft gamma rays, followed by a softer and much dimmer pulsating tale lasting a few hundred...
