Skip to content
DraconiticResearch
Search Sources API
203,234 studies31 sourcesUpdated 47 min ago
Peer-reviewedCC BY 4.0The Astrophysical Journal

Large Offsets of Double-neutron-star Mergers: Degeneracies and Implications for Host Associations

  • Xiao-Tian 啸天 Xu 徐1
  • Bin-Bin Zhang2,3
  • Wenjie Wu4
  • Suoning Wang2,3
4 affiliations
  1. 1Shanghai Jiao-Tong University
  2. 2Nanjing University
  3. 3Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University)
  4. 4Universität Bonn
Open at sourcePDFDOICite

Abstract

The projected offset of a gamma-ray burst (GRB) from its host galaxy is an important diagnostic of its physical origin, where the host associations are usually evaluated through chance-coincidence probabilities. However, as shown by observations, the host associations given by this approach may be ambiguous in some cases. In this work, we revisit the modelling of the offsets of double-neutron-star (DNS) mergers with controlled numerical experiments using Monte Carlo simulations. To isolate the dynamical effects of the second supernova (SN) from uncertainties in the upstream binary evolution, we parametrize the direct progenitor of DNSs and integrate the post-SN trajectories in galactic potentials using galpy . Complementary to previous population synthesis calculations, our Monte Carlo tool, GRB-offset , provides a lightweight framework to identify sensitivities and expose degeneracies in offset modelling. With GRB-offset , we have investigated the following physical ingredients: SN physics (ejected mass and kick velocity), galactic potential (potential shape, galaxy virial mass), DNS birth location, star formation history, and redshift. The offset distributions given by our reference Monte Carlo simulation peak at around 30 and 1000 kpc for the DNSs bound to and unbound from the host galaxy, which sensitively depends on the considered physical ingredients. A given offset can arise from various combinations of these ingredients, introducing substantial degeneracies when interpreting observed offsets. Therefore, an observed offset alone can hardly constrain the properties of the DNS progenitor and of the host galaxies.

Related

  1. Multipolar neutrino radiation in binary neutron star mergers: Angular structure, rotational variability, and implications for electron fraction
    Kutay Arınç Çokluk, Albino Perego, Federico Maria Guercilena +1
    arXivPreprintCC BY 4.0Full textHigh-energy astrophysicsGravitation & general relativityarXiv
  2. Constraining equation of state of neutron star using neutron star-black hole mergers
    Vasudev Dubey, Rahul Kashyap, Yugesh Bhoge
    arXivPreprintarXiv licenceFull textHigh-energy astrophysicsGravitation & general relativityarXiv
  3. Tidal disruption or plunge: the role of neutron star internal structure in black hole-neutron star mergers
    Yatharth Chaurasiya, Ritam Mallick
    arXivPreprintCC BY 4.0Full textHigh-energy astrophysicsarXiv
  4. The presence and order of QCD phase transitions from gravitational-wave observations of neutron star mergers
    Paul D. Lasky, Alexander Clevinger, Andre G. da Silva +2
    arXivPreprintCC BY 4.0Full textHigh-energy astrophysicsGravitation & general relativityarXiv
  5. The imprint of individual neutron star spins on ejecta, r -process nucleosynthesis, and kilonovae in binary neutron star mergers
    Beyhan Karakaş, Rahime Matur, David Radice +2
    Monthly Notices of the Royal Astronomical SocietyPeer-reviewedCC BY 4.0Full textSolar & stellar physicsCrossref

Cite

BibTeXRIS
BibTeX
@article{徐2026large,
  title = {{Large Offsets of Double-neutron-star Mergers: Degeneracies and Implications for Host Associations}},
  author = {Xiao-Tian 啸天 Xu 徐 and Bin-Bin Zhang and Wenjie Wu and Suoning Wang},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = nov,
  doi = {10.3847/1538-4357/aeb027},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeb027},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Large Offsets of Double-neutron-star Mergers: Degeneracies and Implications for Host Associations
AU  - Xiao-Tian 啸天 Xu 徐
AU  - Bin-Bin Zhang
AU  - Wenjie Wu
AU  - Suoning Wang
PY  - 2026
DA  - 2026/11/05
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/aeb027
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/aeb027
AB  - The projected offset of a gamma-ray burst (GRB) from its host galaxy is an important diagnostic of its physical origin, where the host associations are usually evaluated through chance-coincidence probabilities. However, as shown by observations, the host associations given by this approach may be ambiguous in some cases. In this work, we revisit the modelling of the offsets of double-neutron-star (DNS) mergers with controlled numerical experiments using Monte Carlo simulations. To isolate the dynamical effects of the second supernova (SN) from uncertainties in the upstream binary evolution, we parametrize the direct progenitor of DNSs and integrate the post-SN trajectories in galactic potentials using galpy . Complementary to previous population synthesis calculations, our Monte Carlo tool, GRB-offset , provides a lightweight framework to identify sensitivities and expose degeneracies in offset modelling. With GRB-offset , we have investigated the following physical ingredients: SN physics (ejected mass and kick velocity), galactic potential (potential shape, galaxy virial mass), DNS birth location, star formation history, and redshift. The offset distributions given by our reference Monte Carlo simulation peak at around 30 and 1000 kpc for the DNSs bound to and unbound from the host galaxy, which sensitively depends on the considered physical ingredients. A given offset can arise from various combinations of these ingredients, introducing substantial degeneracies when interpreting observed offsets. Therefore, an observed offset alone can hardly constrain the properties of the DNS progenitor and of the host galaxies.
SN  - 1538-4357
SN  - 0004-637X
ER  -