POSYDON: A General-Purpose Population Synthesis Code with Detailed Binary-Evolution Simulations

Abstract

Most massive stars are members of a binary or a higher-order stellar systems, where the presence of a binary companion can decisively alter their evolution via binary interactions. Interacting binaries are also important astrophysical laboratories for the study of compact objects. Binary population synthesis studies have been used extensively over the last two decades to interpret observations of compact-object binaries and to decipher the physical processes that lead to their formation. Here, we present POSYDON, a novel , binary population synthesis code that incorporates full stellar-structure and binary-evolution modeling, using the MESA code, throughout the whole evolution of the binaries. The use of POSYDON enables the self-consistent treatment of physical processes in stellar and binary evolution, including: realistic mass-transfer calculations and assessment of stability, internal angularmomentum transport and tides, stellar core sizes, mass-transfer rates and orbital periods. This paper describes the detailed methodology and implementation of POSYDON, including the assumed physics of stellar-and binary-evolution, the extensive grids of detailed single-and binary-star models, the post-processing, classification and interpolation methods we developed for use with the grids, and the treatment of evolutionary phases that are not based on pre-calculated grids. The first version of POSYDON targets binaries with massive primary stars (potential progenitors of neutron stars or black holes) at solar metallicity.

The χeff − z correlation of field binary black hole mergers and how 3G gravitational-wave detectors can constrain it

“…This study uses the isolated binary evolution model presented in Bavera et al (2022a), calculated using the POSYDON framework (Fragos et al 2022), which accounts for BBH formation through the CE, SMT, and CHE channels. It has been shown that this model (i) leads to BBH observable properties consistent with the events of the second LIGO-Virgo GW transient catalog (GWTC-2) (Zevin et al 2021); (ii) have BBH merger rate estimates compatible with the observational constraints of GWTC-2 -and now GWTC-3 (Bavera et al 2021a;du Buisson et al 2020); (iii) the subpopulation of highly spinning BBHs might explain the observed population of luminous LGRBs across the cosmic history of the Universe (Bavera et al 2022a); and (iv) does not violate current upper limit estimates of the stochastic GW background (Bavera et al 2022b).…”

The $χ_\mathrm{eff}-z$ correlation of field binary black hole mergers and how 3G gravitational-wave detectors can constrain it

“…This study uses the isolated binary evolution model presented in Bavera et al (2022), calculated using the POSYDON framework (Fragos et al 2022), which accounts for BBH formation through the CE, SMT, and CHE channels. It was shown that this model (i) leads to BBH observable properties consistent with the events of the second LIGO-Virgo GW transient catalog (GWTC-2) (Zevin et al 2021), (ii) have BBH merger rate estimates compatible with observational constraints of GWTC-2 and, now GWTC-3, (Bavera et al 2021a;du Buisson et al 2020), (iii) the subpopulation of highly spinning BBHs might explain the observed population of luminous LGRBs across the cosmic history of the Universe (Bavera et al 2022), and (iv) does not violate current upper limit estimates of the stochastic GW background (Bavera et al 2021b).…”

Suspicious Siblings: The Distribution of Mass and Spin across Component Black Holes in Isolated Binary Evolution

“…g., MacLeod & Ramirez-Ruiz 2015; Cruz-Osorio & Rezzolla 2020). The spin of the second-born BH is determined using the semianalytic fits from Bavera et al(2021a), which are based on the detailed spin evolution of BH-WR systems during tidal spin-up using the MESA simulations(Paxton et al 2011(Paxton et al , 2013(Paxton et al , 2015(Paxton et al , 2018(Paxton et al , 2019 under the POSYDON 7 framework(Fragos et al 2022) Bavera et al (2021a). found the spin of the second-born BH to be well approximated by a quadratic function dependent on BH-WR log…”