Goal 2

Massive stars are rarely born alone. They form in binaries and multiple systems, exchanging mass as they evolve. The stars’ fates become intertwined as their very appearance and lifetimes are influenced by close companions. At late stages, after the more massive star has exploded, close binaries are revealed as the neutron star or black hole remnant violently absorbs matter from its companion and reveals itself as a bright X-ray source switching from predominantly soft (<10 keV) to hard (>10 keV) states and back again as different components dominate.

Goal 2 investigates how binary systems live and die, highlighted as a key question by Astro2020. 

• Objective 4: will determine how accreting binary populations depend on the local environment by surveying the Galactic Center and four nearby galaxies.

For more information about Goal 2, see Mori et al. (FrASS, submitted; arXiv:2311.04854, and Lehmer et al. (2023; FrASS, 10, 1293918).