Forward Modeling of Double Neutron Stars: Insights from Highly Offset Short Gamma-Ray Bursts

Michael Zevin*, Luke Zoltan Kelley, Anya Nugent, Wen Fai Fong, Christopher Philip Luke Berry, Vicky Kalogera

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


We present a detailed analysis of two well-localized, highly offset short gamma-ray bursts-GRB 070809 and GRB 090515-investigating the kinematic evolution of their progenitors from compact object formation until merger. Calibrating to observations of their most probable host galaxies, we construct semi-analytic galactic models that account for star formation history and galaxy growth over time. We pair detailed kinematic evolution with compact binary population modeling to infer viable post-supernova velocities and inspiral times. By populating binary tracers according to the star formation history of the host and kinematically evolving their post-supernova trajectories through the time-dependent galactic potential, we find that systems matching the observed offsets of the bursts require post-supernova systemic velocities of hundreds of kilometers per second. Marginalizing over uncertainties in the stellar mass-halo mass relation, we find that the second-born neutron star in the GRB 070809 and GRB 090515 progenitor systems received a natal kick of credible levels, respectively. Applying our analysis to the full catalog of localized short gamma-ray bursts will provide unique constraints on their progenitors and help unravel the selection effects inherent to observing transients that are highly offset with respect to their hosts.

Original languageEnglish (US)
Article number190
JournalAstrophysical Journal
Issue number2
StatePublished - Dec 1 2020


  • Compact binary stars (283)
  • Galaxy evolution (594)
  • Gamma-ray bursts (629)
  • Neutron stars (1108)
  • Stellar evolution (1599)
  • Supernova dynamics (1664)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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