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Ninth International Fermi Symposium

12–17 Apr 2021
Africa/Johannesburg timezone

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Session

Exploring the Cosmos: GRB-1

14 Apr 2021, 18:15

Conveners

Exploring the Cosmos: GRB-1: Parallel-9

  • Peter Veres

Presentation materials

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  1. 73. A Decade of Gamma-ray Bursts Observed by Fermi-GBM
    Dr Andreas von Kienlin (MPE)
    14/04/2021, 18:15
    Gamma-ray Bursts
    Contributed

    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...

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  2. 74. Photospheric emission in GRBs observed by Fermi/GBM
    Felix Ryde
    14/04/2021, 18:30
    Gamma-ray Bursts
    Contributed

    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...

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  3. 75. GRB 160625B: Evidence for a Gaussian-Shaped Jet
    Virginia Cunningham
    14/04/2021, 18:45
    Gamma-ray Bursts
    Contributed

    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...

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  4. 76. "Pulsar Wind" model of early GRB Afterglows
    Maxim Lyutikov
    14/04/2021, 19:00
    Gamma-ray Bursts
    Contributed

    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 ...

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  5. 77. Magnetar Giant Flares as Gamma-Ray Bursts
    Rachel Hamburg
    14/04/2021, 19:15
    Gamma-ray Bursts
    Contributed

    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...

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  6. 78. High-Energy Emission from a Magnetar Giant Flare in the Sculptor Galaxy
    Niccolo' Di Lalla
    14/04/2021, 19:30
    Gamma-ray Bursts
    Contributed

    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...

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