Published: ApJL,
Weakly-kicked neutron stars are required to explain observed double neutron stars and globular cluster pulsars, but this is in apparent conflict with the observed dearth of low-velocity pulsars. In this study, we explore this tension using rapid population synthesis.
Recommended citation: Willcox, R., et al. (2021). " Constraints on Weak Supernova Kicks from Observed Pulsar Velocities ." ApJL . 920(L37).
Published: ApJL,
Non-conservative binary mass transfer requires some treatment of the angular momentum loss of non-accreted matter. In rapid population synthesis, the available models are approximate, and do not self-consistently treat the angular momentum loss with the response of the donor star to mass loss. In this study, I quantify the impact of ignoring this problem on the fraction of interacting binary systems which ultimately experience a common envelope or not.
Recommended citation: Willcox, R., et al. (2023). " The Impact of Angular Momentum Loss on the Outcomes of Binary Mass Transfer.& quot; ApJL . 958(138).
Published: A&A,
Inert black hole binaries preserve the binary orbit as it was immediately after the core-collapse event. When observing conditions allow for a complete characterization of the orbit, this can provide vital information on the formation properties of the black hole, in particular its natal kick and mass loss. In this paper, we introduce a new Bayesian inference package for inert black hole binaries, SideKicks.jl, and explore which observing conditions are needed to estimate the kick and mass loss.
Recommended citation: Willcox, R., et al. (2025). " Binarity at LOw Metallicity (BLOeM): Bayesian inference of natal kicks from inert black hole binaries." A&A . 700(A59).
Recent advancements in stellar evolution theory suggest that key properties of the core structure of stars prior to core-collapse are bimodal functions of the intial mass, that this bimodality is only weakly affected by mass transfer interactions, and that the resulting newborn black hole population has a bimodal mass distribution. Building on this, I show how this bimodal black hole mass structure can be validated with recent observations of merging binary black holes, which show a corresponding trimodal structure in the chirp mass. Moreover, the observed relative heights of the three chirp mass peaks are sensitive to uncertain physics in the interactions of the binary, providing constraints on binary evolution.