New Developments in Gamma-ray Bursts

Topic: Extragalactic Astrophysics

Session Title: New Developments in Gamma-ray Bursts

Description:

Our understanding of gamma-ray burst (GRB) emission has undergone rapid revision over the past few years. The upper limits of jet power from a stellar mass source have been tested by the “Brightest Of All Time” (BOAT) GRB 221009A, a once-per-millennium event whose very ordinary accompanying supernova provided key insights into how energy was partitioned in the collapsing star. On either side of it, the long-lived merger GRBs 211211A and 230307A and their associated kilonovae caused upheaval in the canonical GRB classification scheme that separates neutron star mergers from massive star collapse on either side of a duration divide of two seconds. The unusual zoo of merger-driven bursts also includes GRB 191019A, proposed to be the first identified dynamical capture merger, perhaps from within the accretion disc of a supermassive black hole. New insights into jet launch physics have also been gleaned from the discoveries of the first orphan (gamma-ray free) afterglows AT2019pim and AT2023lcr, both of which are candidates for the long-hypothesised class of baryon-choked “dirty fireballs.”

At the same time, new windows on the Universe are opening. In the X-rays, the launch of the Einstein Probe (EP) and the Space Variable Object Monitor (SVOM), augmented by a fleet of new gamma-ray cubesats, provide new (lobster) eyes in space. In the optical and infra-red, the time domain revolution continues as GOTO joins ZTF and ATLAS in the fast-and-wide discovery space, with Rubin/LSST and BlackGem around the corner. The community also awaits the next GW-EM multi-messenger event as the 4th LVK observing run continues and the GW interferometer network range grows. This rapid expansion of detection possibilities presents the chance to find GRBs in new and exciting ways, broadening the selection criteria, and probing new regions of parameter space.

Our proposed session will review the rapid recent advances in GRB observational studies and accompanying theoretical developments, as well as the next era of GRB discovery with the suite of new facilities. We will cover broad topics through the lens of GRBs, including:

• Jet physics
• GRB classification
• GRBs as multi-messenger sources
• Kilonovae
• Heavy element nucleosynthesis
• Stellar populations
• Host galaxies
• The GRB-supernova connection
• Gravitational lensing
• The future of GRB discovery

Organiser(s): Ben Gompertz (Birmingham); Gavin Lamb (Liverpool John Moores); Samantha Oates (Lancaster)

Schedule:

Venue: WILB-LT27

Session 1: Wednesday 17^th July, 09:00 – 11:00