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Accreting binary populations in Nearby Galaxies: Observations and Simulations

Final Report Summary - A-BINGOS (Accreting binary populations in Nearby Galaxies: Observations and Simulations)

Accreting binaries are binary stellar systems consisting of a compact object that accretes material from a donor star. The compact object can be either a white dwarf, a neutron star, or a black hole, while the donor star can be either a massive star (High-mass X-ray binaries), or a low mass star (Low-mass X-ray binaries). Since accreting binaries are the end-points of stellar evolution are key for understanding the final stages of stellar evolution, and our main tool for studying the populations of black-holes and neutron stars. In addition very energetic phenomena such as mergers between compact objects resulting in gravitational wave sources or short gamma-ray bursts are the endpoints of the evolution of accreting binaries. The goal of this project is to study the formation and evolution mechanisms that produce the different types of accreting binaries observed in nearby galaxies. We can achieve this by correlating the accreting binary populations in nearby galaxies with their recent and past star-forming activity, and comparing these results with models for the formation and evolution of accreting binaries.

The main achievements of this program so far are:
1. The characterization of the accreting binary populations in a sample of nearby galaxies, and the study of the individual sub-populations (High-mass X-ray binaries, Low-mass X-ray binaries).
2. The development of a new method for modeling the accreting binary populations in galaxies
3. The direct measurement of the formation efficiency of young accreting binaries as a function of the age of their parent stellar populations.
4. Systematic studies of the young and old stellar populations in nearby galaxies, which showed strong correlation between them in rather small spatial scales (1 kpc^2; the so-called sub-galactic main sequence).
5. Determination of the relation between the X-ray emission of galaxies and their young and old stellar populations in galaxy-wide and subgalactic scales.
6. Development of diagnostics for the classification of the compact objects in accreting binaries and its application in a sample of nearby galaxies.
7. Development of a new powerful tool for the identification of SNRs in nearby galaxies and the derivation of their Ha luminosity function and their excitation function.
8. The definition of the most complete census of galaxies in the local Universe with robust information on their distance, star-formation rate, and stellar mass.
9. The most complete census of ultra-luminous X-ray sources and determination of their dependence on star-forming activity and stellar mass.