Description
Organiser: Gavin Lamb; co organiser: Kendall Ackley, Dimple, Ben Gompertz, Nusrin Habeeb, Shiho Kobayashi, Joe Lyman, Soheb Mandhai, Conor Omand, Patricia Schady, Nial Tanvir
Gamma-ray bursts are shining beacons that mark the moment of black-hole formation following the violent core-collapse of massive-stars, and the gravitational-wave-driven mergers of neutron-star binaries. The electromagnetic observations of gamma-ray bursts and their accompanying transients (the afterglow and supernova or kilonova) continue to reveal unexpected phenomenology, and generate new questions, some of which multi-messenger probes will answer. One such example is the long held assumption that the population-level bimodality of observed burst-duration clearly indicates the gamma-ray burst progenitor. This has been spectacularly cast in doubt following the discovery of kilonovae (merger origin) following two long-duration gamma-ray bursts (classically assumed to be core-collapse supernovae), GRB211211A and GRB230307A โ where JWST observations of the latter, were crucial in determining the merger origin. These transient events originate in extreme astrophysical environments where: heavy elements are synthesised (r-process nucleosynthesis) and thrown out to enrich their host-galaxy (see GRB230307A); space-time is twisted and highly curved (Kerr metric), relativistic jets are launched and matter is accelerated to > 99.995% the speed of light; ionising radiation is emitted in beams from host galaxies out to, at least, z~9.4 (see GRB090429B), within or before the era of reionization; gravitational-waves are combined with highly luminous electromagnetic signals (GRB170817A); and the ideal conditions (large energy densities and magnetic fields, relativistic shocks, neutrino winds, particle acceleration etc.) for astro-particle experiments.
This session will highlight new observations, theory, modelling developments for gamma-ray bursts and related multi-messenger transients, their influence on their environments, and the discovery potential of new and upcoming instruments.
Binary neutron star mergers and collapsing massive stars can both create millisecond magnetars. Such magnetars are candidate engines to power gamma-ray bursts (GRBs). The non-thermal light curve of the resulting transients can exhibit multiple components, including: the GRB afterglow, pulsar wind nebula (PWN), and ejecta afterglow. We derive the timescales for the peak of each component...
Einstein Probe has opened a new window into X-ray transients, particularly the diverse sample of fast X-ray transients (FXTs) that it is uncovering. These FXTs show a wide range of properties and some have been linked to known transient classes including gamma-ray bursts (GRBs). In this talk, I will discuss one recently detected FXT with unique and fascinating behaviour, EP250108a/SN 2025kg...
The Palomar 60-inch (1.5 metre) telescope conducted an automated optical GRB follow-up programme from 2005 to 2017. It was configured to respond automatically, in less than three minutes, to well-localised GRB alerts, and it was one of the largest optical telescopes with such a programme at the time. The rapid response to the alerts resulted in 88 follow-up observations within one hour of...
We present the first gamma-ray burst (GRB) host galaxy with a measured absorption line and electron temperature (T$_e$) based metallicity, using the temperature sensitive [OIII]$\lambda$4363 auroral line detected in the JWST/NIRSpec spectrum of the host of GRB 050505 at redshift $z=4.28$. This direct measurement of the emission line metallicity allows us, for the first time, to bridge the gap...
The radiation mechanism of the prompt emission is still an open issue and can be resolved using a systematic and uniform time-resolved spectro-polarimetric study. In this work, we performed a comprehensive investigation of the spectral, temporal, and polarimetric characteristics of bright GRBs observed using the AstroSat CZTI, Fermi GBM, and Swift-BAT to provide insight into the prompt...
Long GRBs are traditionally thought to come from collapsing stars and short GRBs to originate from binary neutron star mergers. However, the discoveries of kilonovae coincident with GRB 211211A and GRB 230307A provide conclusive evidence that some long GRBs can in fact originate from BNS mergers. These long merger GRBs can in part be classified by the existence of an extended plateau of...
Polarisation measurements of gamma-ray burst afterglows provide a powerful tool for probing the structure of relativistic jets.
In this talk, I will discuss polarisation signatures of gamma-ray burst afterglows, emphasising deviations from the classical model for axisymmetric top-hat jets, which predicts two polarisation peaks and a 90-degree position angle rotation.
Observations of...
The radiation mechanisms powering Gamma-ray bursts (GRBs) and the physical processes shaping their relativistic jets remain one of the unresolved questions in high-energy astrophysics. Spectro-polarimetric observations of exceptionally bright GRBs offer a promising pathway to address these challenges. GRB 230307A, the second-brightest long GRB ever detected, with an isotropic gamma-ray energy...
Long gamma-ray bursts (GRBs) serve as powerful tools for probing the properties of distant galaxies. Their luminous afterglows pinpoint galaxies independent of their intrinsic luminosity. However, this selection method is subject to biases based on the properties of the progenitor stars linked to each host galaxy. Characterising the galaxy populations traced by GRBs is therefore important both...
GRB 241105A challenges traditional GRB classification, exhibiting properties at the boundary between short and long bursts. Its prompt emissionโan initial hard spike with weaker extended emissionโwas detected by Fermi-GBM, Swift-BAT, and Konus-Wind. Spectral analysis using Power-Law, Comptonized, and Band function models, along with classification metrics such as spectral lag, hardness ratio,...
Even with tens of thousands of Gamma-Ray Burst (GRB) detected on an average of one per day, the emission process of this highly-energetic phenomenon is unclear. Additionally, the GRB prompt-phase spectrum can be reproduced by multiple empirical functions within the statistical significance adding further dubiety. The scepticism can be resolved, at least partially, by studying the spectral...
A strong correlation not predicted by the standard model of gamma-ray burst (GRB) afterglows exists across multiple bands between the intrinsic brightness and temporal decay rate of long GRBs. Using population analysis methods, we investigated the underlying physical mechanisms that leads to the correlation, applying different GRB jet structures to produce afterglows within the REDBACK code....
