2023/08/31 by Ore Gottlieb, Gottlieb, Ore, Brian D. Metzger +11 · 9 citations
Physics and Astronomy · #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2309.00038
openalex publication_date 2023/08/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The recent detections of the ∼10-s long γ-ray bursts (GRBs) 211211A and 230307A followed by softer temporally extended emission (EE) and kilonovae, point to a new GRB class. Using state-of-the-art first-principles simulations, we introduce a unifying theoretical framework that connects binary neutron star (BNS) and black hole-NS (BH-NS) merger populations with the fundamental physics governing compact-binary GRBs (cbGRBs). For binaries with large total masses M\rm tot\gtrsim2.8 M_\odot, the compact remnant created by the merger promptly collapses into a BH, surrounded by an accretion disk. The duration of the pre-magnetically arrested disk (MAD) phase sets the duration of the roughly constant power cbGRB and could be influenced by the disk mass, Md. We show that massive disks (Md\gtrsim0.1 M_\odot), which form for large binary mass ratio q\gtrsim1.2 in BNS or q\lesssim3 in BH-NS mergers, inevitably produce 211211A-like long cbGRBs. Once the disk becomes MAD, the jet power drops with the mass accretion rate as M∼ t-2, naturally establishing the EE decay. Two scenarios are plausible for short cbGRBs. They can be powered by BHs with less massive disks, which form for other q values. Alternatively, for binaries with M\rm tot\lesssim2.8 M_\odot, mergers should go through a hypermassive NS (HMNS) phase, as inferred for GW170817. Magnetized outflows from such HMNSs, which typically live for \lesssim1 \rm s, offer an alternative progenitor for short cbGRBs. The first scenario is challenged by the bimodal GRB duration distribution and the fact that the Galactic BNS population peaks at sufficiently low masses that most mergers should go through a HMNS phase.