Accreting black holes and neutron stars in X-ray binaries (XRBs) provide an ideal laboratory for studying compact object physics as well as the physics of accretionthe most efficient mechanism of energy production known. This project (XB-LAB), building on prior initiatives (AYA2017-83216-P, PID2021- 124879NB-I00, and PID2020-120323GB-I00) led by the equipo-de-investigación, aims to explore both areas. Our internationally recognised team at the IAC, together with renowned international collaborators, brings extensive expertise and access to world-class observing facilities, enabling us to propose this four-year project with three major goals.
The first goal is to utilise our unique dataset, enhanced by new observations from top-tier X-ray, optical, and near-infrared facilities, for a detailed study of accretion disc winds. We aim to delineate their observational properties, understand their relationships with the accretion flow and radio jets, and examine the role of accretion disc size and line-of-sight on their visibility and kinematics. We will also investigate the physical properties and geometry of these outflows, employing advanced modelling techniques to analyse wind-related line profiles and assess wind-launching mechanisms.
The second goal focuses on ultracompact XRBs, a family of XRBs with orbital periods under 80 minutes, which provide insights into binary evolution and accretion processes. These systems will be primary sources for the forthcoming LISA mission, involving neutron stars or black holes accreting from degenerate donors like white dwarfs, and are key for studying phenomena like the common-envelope phase. Using our comprehensive catalogue developed during PID2020, UltraCompCAT, we will expand our understanding through rigorous campaigns and analysis with novel facilities to measure orbital periods, identify spectral features, and validate diagnostics for these intriguing systems.
The third goal of XB-LAB is to expand the mass measurements of compact objects (i.e., black holes and neutron stars) across a broader range of XRB transients, increasing our catalogue of systems with detectable counterparts and conducting dedicated mass measurement programmes. These efforts will enable us to evaluate theories of massive star collapse and provide crucial data for classifying and understanding the physical characteristics of these systems, even those that are elusive in quiescence.
