On the Impact of Neutron Star Binaries Natal-Kick Distribution on the Galactic r-process Enrichment

Abstract

We study the impact of the neutron star binaries' (NSBs) natal kick distribution on the Galactic r-process enrichment. We model the growth of a Milky Way type halo based on N-body simulation results and its star formation history based on multi epoch abundance matching techniques. We consider the NSBs that merge well beyond the galaxy's effective radius ($>2\times R_{\mathrm{eff}}$) do not contribute to Galactic r-process enrichment. Assuming a power-law delay-time distribution (DTD) function ($\propto t^{-1}$) with $t_{\min }=30$ Myr for binaries' coalescence timescales, and an exponential profile for their natal kick distribution with an average value of 180 km s${}^{-1}$, we show that up to $\sim$ 40% of all formed NSBs do not contribute to r-process enrichment by $z=0$, either because they merge far from the galaxy at a given redshift (up to $\sim$ 25%) or have not yet merged by today ($\sim$15%). Our result is largely insensitive to the details of the DTD function. Assuming a constant coalescence timescale of 100 Myr well approximates the adopted DTD with 30% of the NSBs not contributing to r-process enrichment. Our results, although rather dependent on the adopted natal kick distribution, represent a first step towards estimating the impact of natal kicks and DTD functions on r-process enrichment of galaxies that would need to be incorporated in the hydrodynamical simulations.

7 pages, 3 figures, MNRAS Accepted

References in corpus (12)

• 3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since $z=3$
• Magnetorotationally driven Supernovae as the origin of early galaxy $r$-process elements?
• Upper limits on the rates of binary neutron star and neutron-star--black-hole mergers from Advanced LIGO's first observing run
• Galactic r-process enrichment by neutron star mergers in cosmological simulations of a Milky Way-mass galaxy
• The History of R-Process Enrichment in the Milky Way
• The role of neutron star mergers in the chemical evolution of the Galactic halo
• Neutron Star Mergers as the Origin of r-Process Elements in the Galactic Halo Based on the Sub-halo Clustering Scenario
• Advanced LIGO Constraints on Neutron Star Mergers and R-Process Sites
• Natal Kicks and Time Delays in Merging Neutron Star Binaries - Implications for r-process nucleosynthesis in Ultra Faint Dwarfs and in the Milky Way
• Contribution of Neutron Star Mergers to the R-process Chemical Evolution in the Hierarchical Galaxy Formation
• Simulating Neutron Star Mergers as r-process Sources in Ultra Faint Dwarf Galaxies
• Early chemo-dynamical evolution of dwarf galaxies deduced from enrichment of r-process elements

Cited by in corpus (1)

• Current Status of r-Process Nucleosynthesis