Conveners
Unusual and New Types of Gamma-Ray Bursts: Block 1
- Binbin Zhang (Nanjing University)
Description
This session focuses on GRBs with unusual temporal, spectral, and multi-messenger properties, as well as new types of GRBs with new physical origins (such as Giant Flare GRBs).
We present the observations of the first unambiguous magnetar giant flare from outside of our galactic neighborhood. Initially, GRB 200415A was identified as a short GRB, but upon further investigation and observations from additional instruments, we concluded this event was a giant flare from a magnetar located in the Sculptor galaxy, 3.5 Mpc away. The GBM lightcurve shows very fast (shorter...
Cosmological Gamma-Ray Bursts (GRBs) are known to arise from distinct progenitor channels: short GRBs mostly from neutron star mergers and long GRBs from a rare type of core-collapse supernova (CCSN) called collapsars. Highly magnetized neutron stars called magnetars also generate energetic, short-duration gamma-ray transients called Magnetar Giant Flares (MGFs). Three have been observed from...
The giant flares of soft gamma-ray repeaters (SGRs) have long been proposed to contribute to at least a subsample of the observed short gamma-ray bursts (GRBs). We performed a comprehensive analysis of the high-energy data of the bright short GRB 200415A, which was located close to the Sculptor galaxy. Our results suggest that a magnetar giant flare provides the most natural explanation for...
We present the current state of the art of observational properties of
the class of ultra-long GRBs and discuss of any potential method to
classify them as ultra-long while the prompt emission is still active.
We also discuss their detectability in light of the new experiments
currently planned.
Gamma-ray bursts (GRBs) are among the brightest and most energetic events in the universe. The duration and hardness distribution of GRBs has two clusters, now understood to reflect (at least) two different progenitors. Short-hard GRBs (SGRBs; T90 <2 s) arise from compact binary mergers, while long-soft GRBs (LGRBs; T90 >2 s) have been attributed to the collapse of peculiar massive stars...
On 26th August 2020,gamma-ray burst monitor onboard Fermi satellite was triggered by an unprecedented genuinely short burst GRB 200826A which is totally different from either of the previous strange ones. The undoubtedly short duration and its proximity, together with large f parameter, prove its genuine short-duration fact. For more metrics, we immediately exploit the prompt and afterglow...
We propose a possible model of explaining recently discovered short GRB 200826A, unifying this event and normal long GRBs from collapsars. The turbulent nature of relativistic jets is responsible for inhomogeneity, resulting in a lot of patchy emission regions in the jet. If such an emission patch is viewed, a short single pulse is observed, while the usual long GRBs are observed when...
Recently, ground-based Imaging Atmospheric Cherenkov Telescopes, such as MAGIC and H.E.S.S., have reported the detection of very-high-energy (VHE) gamma-rays from three gamma-ray bursts (GRB 180720B, 190114C, 190829A). One of them, GRB 190829A, was triggered by the Swift satellite, and about 20000 s after the burst onset the VHE gamma-ray emission was detected by H.E.S.S. with ~ 5 sigma...
