The multimessenger picture of compact object encounters: Binary mergers versus dynamical collisions

  • Rosswog S
  • Piran T
  • Nakar E
  • 35


    Mendeley users who have this article in their library.
  • 93


    Citations of this article.


We explore the multi-messenger signatures of encounters between two neutron stars and between a neutron star and a stellar-mass black hole. We focus on the differences between gravitational wave driven binary mergers and dynamical collisions that occur, for example, in globular clusters. For both types of encounters we compare the gravitational wave and neutrino emission properties. We also calculate fallback rates and analyze the properties of the dynamically ejected matter. Last but not least we address the electromagnetic transients that accompany each type of encounter. The canonical nsns merger case ejects more than 1% of a solar mass of extremely neutron-rich ($Y_e\sim 0.03$) material, an amount that is consistent with double neutron star mergers being a major source of r-process in the galaxy. nsbh collisions eject very large amounts of matter ($\sim 0.15$ \msun) which seriously constrains their admissible occurrence rates. The compact object {\em collision} rate must therefore be less, likely much less, than 10% of the nsns {\em merger} rate. The radioactively decaying ejecta produce optical-UV "macronova" which, for the canonical merger case, peak after $\sim 0.4$ days with a luminosity of $\sim 10^{42}$ erg/s. nsns (nsbh) collisions reach up to 3 (7) times larger peak luminosities. The dynamic ejecta deposit a kinetic energy comparable to a supernova in the ambient medium. The canonical merger case releases approximately $2 \times 10^{50}$ erg, the most extreme (but likely rare) cases deposit kinetic energies of up to $10^{52}$ erg. The deceleration of this mildly relativistic material by the ambient medium produces long lasting radio flares. A canonical ns$^2$ merger at the detection horizon of advanced LIGO/Virgo produces a radio flare that peaks on a time scale of one year with a flux of $\sim$0.1 mJy at 1.4 GHz.

Author-supplied keywords

  • Black hole physics
  • Gamma-ray bursts
  • Gravitational waves
  • Neutrinos
  • Nuclear reactions, nucleosynthesis, abundances
  • Radiation mechanisms: non-thermal

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • S. Rosswog

  • T. Piran

  • E. Nakar

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free