No peaks without valleys: learning about massive stars from the masses of merging black holes
Gravitational wave observations are revealing new features in the mass distribution of merging binary black holes (BBHs). The BBHs we observe today are relics of massive stars that lived in the early Universe, and we aim to use their properties to help reveal the lives and deaths of their stellar ancestors.
In this talk, I will discuss which of the observed features are robust, and if/how we can use them to constrain the uncertain progenitor physics. I will focus on the lowest mass BHs, just above the edge of NS formation because we find they I) contain crucial information about the most common formation pathway, II) are least affected by uncertainties in the cosmic star formation, and III) shine new light on the much-disputed mass-gap between neutron stars and black holes.