The case for a minute-long merger-driven gamma-ray burst from fast-cooling synchrotron emission
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For decades, gamma-ray bursts (GRBs) have been broadly divided into long- and short-duration bursts, lasting more or less than 2 s, respectively. However, this dichotomy does not perfectly map to the two progenitor channels that are known to produce GRBs: mergers of compact objects (merger GRBs) or the collapse of massive stars (collapsar GRBs). In particular, the merger GRB population may also include bursts with a short, hard < 2 s spike and subsequent longer, softer extended emission. The recent discovery of a kilonova-the radioactive glow of heavy elements made in neutron star mergers-in the 50-s-duration GRB 211211A further demonstrates that mergers can drive long, complex GRBs that mimic the collapsar population. Here we present a detailed temporal and spectral analysis of the high-energy emission of GRB 211211A. We demonstrate that the emission has a purely synchrotron origin, with both the peak and cooling frequencies moving through the gamma-ray band down to X-rays, and that the rapidly evolving spectrum drives the extended emission signature at late times. The identification of such spectral evolution in a merger GRB opens avenues to diagnostics of the progenitor type.
Original language | English |
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Journal | Nature Astronomy |
Volume | 7 |
Pages (from-to) | 67-79 |
Number of pages | 13 |
ISSN | 2397-3366 |
DOIs | |
Publication status | Published - 2022 |
- EXTENDED EMISSION, HIGH-REDSHIFT, NEUTRON-STAR, LIGHT CURVES, MODEL, DUST, ABSORPTION, ACCRETION, CONSTRAINTS, EVOLUTION
Research areas
ID: 330778876